35Elements of Chem. Phil.p. 46.These remarks are founded upon distinctions which have no real existence. We cannot separatethingsfrom theirproperties, nor can we consider their properties and analogies in any other way than by havingopinionsabout them. By contrastinganalogieswithopinions, it might appear as if the author maintained that there were certain analogies about which there was no room for erroneous opinions. Yet the analogies of chemical compounds, are, in fact, those points which have been most the subject of difference of opinion, and on which the revolutions of theories have most changed men’s views. As an example of analogies which are still recognized under alterations of theory, the writer gives the relation of a metal to its oxide or calciform state. But this analogy of metallic oxides, as Red Copper or Iron Ore, to Calx, or burnt lime, is very far from being self-evident;—so far indeed, that the recognition of the analogy was a great step in chemicaltheory. The terms which he quotes,oxygenated muriatic acid(and the same may be said ofdephlogisticated marine acid,) if improper, are so not because they involve theory, but because they involve false theory;—not because those who framed them did not endeavour to express analogies, but because they expressed analogies about which they were mistaken. Unconnected names, asmetals,earths,alkalis, are good as thebasisof a systematic nomenclature, but they are not substitutes for such a nomenclature. A systematic nomenclature is an instrument of great utility and power, as the modern history of chemistry has shown. It would be highly unphilosophical to reject298the use of such an instrument, because, in the course of the revolutions of science, we may have to modify, or even to remodel it altogether. Its utility is not by that means destroyed. It has retained, transmitted, and enabled us to reason upon, the doctrines of the earlier theory, so far as they are true; and when this theory is absorbed into a more comprehensive one, (for this, and not its refutation, is the end of a theoryso far asit is true,) the nomenclature is easily translated into that which the new theory introduces. We have seen, in the history of astronomy, how valuable the theory ofepicycleswas, in its time: the nomenclature of the relations of a planet’s orbit, which that theory introduced, was one of Kepler’s resources in discovering theellipticaltheory; and, though now superseded, is still readily intelligible to astronomers.This is not the place to discuss the reasons for theformof scientific terms; otherwise we might ask, in reference to the objections to the Lavoisierian nomenclature, if such forms asaurumandauraare good to represent the absence or presence of oxygen, why such forms assulphiteandsulphateare not equally good to represent the presence of what we may call a smaller or larger dose of oxygen, so long as the oxygen theory is admitted in its present form; and to indicate still the difference of the same substances, if under any change of theory it should come to be interpreted in a new manner.But I do not now dwell upon such arguments, my object in this place being to show that terms involving theory are not only allowable, if understood so far as the theory is proved, but of great value, and indeed of indispensable use, in science. The objection to them is inconsistent with the objects of science. If, after all that has been done in chemistry or any other science, we have arrived at no solid knowledge, no permanent truth;—if all that we believe now may be proved to be false to-morrow;—then indeed our opinions and theories are corruptible elements, on which it would be unwise to rest any thing important, and which we might wish to exclude, even from our names. But if299our knowledge has no more security than this, we can find no reason why we should wish at all to have names of things, since the names are needed mainly that we may reason upon and increase our knowledge such as it is. If we are condemned to endless alternations of varying opinions, then, no doubt, our theoretical terms may be a source of confusion; but then, where would be the advantage of their being otherwise? what would be the value of words which should express in a more precise manner opinions equally fleeting? It will perhaps be said, our terms must express facts, not theories: but of this distinction so applied we have repeatedly shown the futility. Theories firmly established are facts. Is it not a fact that the rusting of iron arises from the metal combining with the oxygen of the atmosphere? Is it not a fact that a combination of oxygen and hydrogen produces water? That our terms should expresssuchfacts, is precisely what we are here inculcating.Our examination of the history of science has led us to a view very different from that which represents it as consisting in the succession of hostile opinions. It is, on the contrary, a progress, in which each step is recognized and employed in the succeeding one. Every theory, so far as it is true, (and all that have prevailed extensively and long, contain a large portion of truth,) is taken up into the theory which succeeds and seems to expel it. All the narrower inductions of the first are included in the more comprehensive generalizations of the second. And this is performed mainly by means of such terms as we are now considering;—terms involving the previous theory. It is by means of such terms, that the truths at first ascertained become so familiar and manageable, that they can be employed as elementary facts in the formation of higher inductions.These principles must be applied also, though with great caution, and in a temperate manner, even to descriptive language. Thus the mode of describing the forms of crystals adopted by Werner and Romé de l’Isle was to consider an original form, from which other forms are derived bytruncationsof the edges and the300angles. Haüy’s method of describing the same forms, was to consider them as built up of rows of small solids, the angles being determined by thedecrementsof these rows. Both these methods of description involve hypothetical views; and the last was intended to rest on a true physical theory of the constitution of crystals. Both hypotheses are doubtful or false: yet both these methods are good as modes of description: nor is Haüy’s terminology vitiated, if we suppose (as in fact we must suppose in many instances,) that crystalline bodies are not really made up of such small solids. The mode of describing an octahedron of fluor spar, as derived from the cube, by decrements of one row on all the edges, would still be proper and useful as a description, whatever judgment we should form of the material structure of the body. But then, we must consider the solids which are thus introduced into the description as merely hypothetical geometrical forms, serving to determine the angles of the faces. It is in this way alone that Haüy’s nomenclature can now be retained.In like manner we may admit theoretical views into the descriptive phraseology of other parts of Natural History: and the theoretical terms will replace the obvious images, in proportion as the theory is generally accepted and familiarly applied. For example, in speaking of the Honeysuckle, we may say that the upper leaves areperfoliate, meaning that a single round leaf is perforated by the stalk, or threaded upon it. Here is an image which sufficiently conveys the notion of the form. But it is now generally recognized that this apparent single leaf is, in fact, two opposite leaves joined together at their bases. If this were doubted, it may be proved by comparing the upper leaves with the lower, which are really separate and opposite. Hence the termconnateis applied to these conjoined opposite leaves, implying that they grow together; or they are calledconnato-perfoliate. Again; formerly the corolla was calledmonopetalousorpolypetalous, as it consisted of one part or of several: but it is now agreed among botanists that those corollas which301appear to consist of a single part, are, in fact, composed of several soldered together; hence the termgamopetalousis now employed (by De Candolle and his followers) instead of monopetalous36.36On this subject, see Illiger,Versuch einer Systematischen Vollständigen Terminologie für das Thierreich und Pflanzenreich(1810). De Candolle,Théorie Élémentaire de la Botanique.In this way the language of Natural History not only expresses, but inevitably implies, general laws of nature; and words are thus fitted to aid the progress of knowledge in this, as in other provinces of science.AphorismXII.If terms are systematically good, they are not to be rejected because they are etymologically inaccurate.Termsbelonging to a system are defined, not by the meaning of their radical words, but by their place in the system. That they should be appropriate in their signification, aids the processes of introducing and remembering them, and should therefore be carefully attended to by those who invent and establish them; but this once done, no objections founded upon their etymological import are of any material weight. We find no inconvenience in the circumstance thatgeometrymeans the measuring of the earth, that the nameporphyryis applied to many rocks which have no fiery spots, as the word implies, andooliteto strata which have no roelike structure. In like manner, if the termpœcilitewere already generally received, as the name of a certain group of strata, it would be no valid ground for quarrelling with it, that this group was not always variegated in colour, or that other groups were equally variegated: although undoubtedly inintroducingsuch a term, care should be taken to make it as distinctive as possible. It often happens, as we have seen, that by the natural progress of changes in language, a word is steadily confirmed in a sense quite different from its etymological import. But though302we may accept such instances, we must not wantonly attempt to imitate them. I say, not wantonly: for if the progress of scientific identification compel us to follow any class of objects into circumstances where the derivation of the term is inapplicable, we may still consider the term as an unmeaning sound, or rather an historical symbol, expressing a certain member of our system. Thus if, in following the course of themountainorcarboniferouslimestone, we find that in Ireland it does not form mountains nor contain coal, we should act unwisely in breaking down the nomenclature in which our systematic relations are already expressed, in order to gain, in a particular case, a propriety of language which has no scientific value.All attempts to act upon the maxim opposite to this, and to make our scientific names properly descriptive of the objects, have failed and must fail. For the marks which really distinguish the natural classes of objects, are by no means obvious. The discovery of them is one of the most important steps in science; and when they are discovered, they are constantly liable to exceptions, because they do not contain the essential differences of the classes. The natural orderUmbellatæ, in order to be a natural order, must contain some plants which have not umbels, asEryngium37. ‘In such cases,’ said Linnæus, ‘it is of small import what you call the order, if you take a proper series of plants, and give it some name which is clearly understood to apply to the plants you have associated.’ ‘I have,’ he adds, ‘followed the rule of borrowing the nameà fortiori, from the principal feature.’37SeeHist. Ind. Sc.b. xvi. c. iv. sect. 5.The distinction of crystals into systems according to the degree of symmetry which obtains in them, has been explained elsewhere. Two of these systems, of which the relation as to symmetry might be expressed by saying that one issquare pyramidaland the otheroblong pyramidal, or the firstsquare prismaticand the secondoblong prismatic, are termed by Mohs, the first,Pyramidal, and the secondPrismatic. And it may303be doubted whether it is worth while to invent other terms, though these are thus defective in characteristic significance. As an example of a needless rejection of old terms in virtue of a supposed impropriety in their meaning, I may mention the attempt made in the last edition of Haüy’sMineralogy, to substituteautopsideandheteropsideformetallicandunmetallic. It was supposed to be proved that all bodies have a metal for their basis; and hence it was wished to avoid the termunmetallic. But the wordsmetallicandunmetallicmay mean that mineralsseemmetallic and unmetallic, just as well as if they contained the elementopsideto imply this seeming. The old names express all that the new express, and with more simplicity, and therefore should not be disturbed.The maxim on which we are now insisting, that we are not to be too scrupulous about the etymology of scientific terms, may, at first sight, appear to be at variance with ourFourthAphorism, that words used technically are to retain their common meaning as far as possible. But it must be recollected, that in the Fourth Aphorism we spoke ofcommonwordsappropriatedas technical terms; we here speak of wordsconstructedfor scientific purposes. And although it is, perhaps, impossible to draw a broad line between these two classes of terms, still the rule of propriety may be stated thus: In technical terms, deviations from the usual meaning of words are bad in proportion as the words are more familiar in our own language. Thus we may apply the termCirrusto a cloud composed of filaments, even if these filaments are straight; but to call such a cloud aCurl cloudwould be much more harsh.Since the names of things, and of classes of things, when constructed so as to involve a description, are constantly liable to become bad, the natural classes shifting away from the descriptive marks thus prematurely and casually adopted, I venture to lay down the following maxim.304AphorismXIII.The fundamental terms of a system of Nomenclature may be conveniently borrowed from casual or arbitrary circumstances.Forinstance, the names of plants, of minerals, and of geological strata, may be taken from the places where they occur conspicuously or in a distinct form; asParietaria,Parnassia,Chalcedony,Arragonite,Siluriansystem,Purbecklimestone. These names may be considered as at first supplying standards of reference; for in order to ascertain whether any rock bePurbecklimestone, we might compare it with the rocks in the Isle of Purbeck. But this reference to a local standard is of authority only till the place of the object in the system, and its distinctive marks, are ascertained. It would not vitiate the above names, if it were found that theParnassiadoes not grow on Parnassus; thatChalcedonyis not found in Chalcedon; or even thatArragoniteno longer occurs in Arragon; for it is now firmly established as a mineral species. Even in geology such a reference is arbitrary, and may be superseded, or at least modified, by a more systematic determination.Alpinelimestone is no longer accepted as a satisfactory designation of a rock, now that we know the limestone of the Alps to be of various ages.Again, names of persons, either casually connected with the object, or arbitrarily applied to it, may be employed as designations. This has been done most copiously in botany, as for example,Nicotiana,Dahlia,Fuchsia,Jungermannia,Lonicera. And Linnæus has laid down rules for restricting this mode of perpetuating the memory of men, in the names of plants. Those generic names, he says38, which have been constructed to preserve the memory of persons who have deserved well of botany, are to be religiously retained. This, he adds, is the sole and supreme reward of the botanist’s labours, and must be carefully guarded and305scrupulously bestowed, as an encouragement and an honour. Still more arbitrary are the terms borrowed from the names of the gods and goddesses, heroes and heroines of antiquity, to designate new genera in those departments of natural history in which so many have been discovered in recent times as to weary out all attempts at descriptive nomenclature. Cuvier has countenanced this method. ‘I have had to frame many new names of genera and sub-genera,’ he says39, ‘for the sub-genera which I have established were so numerous and various, that the memory is not satisfied with numerical indications. These I have chosen either so as to indicate some character, or among the usual denominations, which I have latinized, or finally, after the example of Linnæus, among the names of mythology, which are in general agreeable to the ear, and which are far from being exhausted.’38Phil. Bot.241.39Règne An.p. 16.This mode of framing names from the names of persons to whom it was intended to do honour, has been employed also in the mathematical and chemical sciences; but such names have rarely obtained any permanence, except when they recorded an inventor or discoverer. Some of the constellations, indeed, have retained such appellations, asBerenice’s Hair; and the new star which shone out in the time of Cæsar, would probably have retained the name given to it, of theJulian Star, if it had not disappeared again soon after. In the map of the Moon, almost all the parts have had such names imposed upon them by those who have constructed such maps, and these names have very properly been retained. But the names of new planets and satellites thus suggested have not been generally accepted; as theMediceanstars, the name employed by Galileo for the satellites of Jupiter; theGeorgium Sidus, the appellation proposed by Herschel for Uranus when first discovered40; CeresFerdinandea,306the name which Piazzi wished to impose on the small planet Ceres. The names given to astronomical Tables by the astronomers who constructed them have been most steadily adhered to, being indeed names of books, and not of natural objects. Thus there were theIlchanic, theAlphonsine, theRudolphine, theCarolinianTables. Comets which have been ascertained to be periodical, have very properly had assigned to them the name of the person who established this point; and of these we have thus,Halley’s,Encke’s Comet, andBiela’sorGambart’s Comet.40In this case, the nameUranus, selected with a view to symmetry according to the mythological order of descent of the persons (Uranus,Saturn,Jupiter,Mars) was adopted by astronomers in general, though not proposed or sanctioned by the discoverer of the new planet. In the cases of the smaller planets,Ceres,Pallas,Juno, andVesta, the names were given either by the discoverer, or with his sanction. Following this rule, Bessel gave the name ofAstræato a new planet discovered in the same region by Mr. Hencke, as mentioned in the additions to book vii. of theHistory(2nd Ed.). Following the same rule, and adhering as much as possible to mythological connexion, the astronomers of Europe have with the sanction of M. Le Verrier, given the name ofNeptuneto the planet revolving beyond Uranus, and discovered in consequence of his announcement of its probable existence, which had been inferred by Mr. Adams and him (calculating in ignorance of each other’s purpose) from the perturbations of Uranus; as I have stated in the Additions to the Third Edition of theHistory.In the case of discoveries in science or inventions of apparatus, the name of the inventor is very properly employed as the designation. Thus we have theTorricellianVacuum, theVoltaicPile,Fahrenheit’sThermometer. And in the same manner with regard to laws of nature, we haveKepler’sLaws,BoyleorMariotte’slaw of the elasticity of air,Huyghens’slaw of double refraction,Newton’sscale of colours.Descartes’law of refraction is an unjust appellation; for the discovery of the law of sines was made by Snell. In deductive mathematics, where the invention of a theorem is generally a more definite step than an induction, this mode of designation is more common, asDemoivre’sTheorem,Maclaurin’sTheorem,Lagrange’sTheorem,EulerianIntegrals.In theHistory of Science41I have remarked that in the discovery of what is termed galvanism, Volta’s307office was of a higher and more philosophical kind than that of Galvani; and I have, on this account, urged the propriety of employing the termvoltaic, rather thangalvanicelectricity. I may add that the electricity of the common machine is often placed in contrast with this, and appears to require an express name. Mr. Faraday calls itcommonormachineelectricity; but I think thatfranklinicelectricity would form a more natural correspondence withvoltaic, and would be well justified by Franklin’s place in the history of that part of the subject.41b. xiii. c. 1.AphorismXIV.The Binary Method of Nomenclature(Names by Genus and Species)is the most convenient hitherto employed in Classification.Thenumber of species in every province of Natural History is so vast that we cannot distinguish them and record the distinctions without some artifice. The known species of plants, for instance, were 10,000 in the time of Linnæus, and are now probably 60,000. It would be useless to endeavour to frame and employ separate names for each of these species.The division of the objects into a subordinated system of classification enables us to introduce a Nomenclature which does not require this enormous number of names. The artifice employed is, to name a specimen by means of two (or it might be more) steps of the successive division. Thus in Botany, each of the Genera has its name, and the species are marked by the addition of some epithet to the name of the genus. In this manner about 1,700 Generic Names, with a moderate number of Specific Names, were found by Linnæus sufficient to designate with precision all the species of vegetables known at his time. And thisBinary Methodof Nomenclature has been found so convenient, that it has been universally adopted in every other department of the Natural History of organized beings.308Many other modes of Nomenclature have been tried, but no other has at all taken root. Linnæus himself appears at first to have intended marking each species by the Generic Name, accompanied by a characteristic Descriptive Phrase; and to have proposed the employment of aTrivialSpecific Name, as he termed it, only as a method of occasional convenience. The use of these trivial names, however, has become universal, as we have said; and is by many persons considered the greatest improvement introduced at the Linnæan reform.AphorismXV.The Maxims of Linnæus concerning the Names to be used in Botany, (Philosophia Botanica, Nomina. Sections 210 to 255)are good examples of Aphorisms on this subject.BothLinnæus and other writers (as Adanson) have given many maxims with a view of regulating the selection of generic and specific names. The maxims of Linnæus were intended as much as possible to exclude barbarism and confusion, and have, upon the whole, been generally adopted.These canons, and the sagacious modesty of great botanists, like Robert Brown, in conforming to them, have kept the majority of good botanists within salutary limits; though many of these canons were objected to by the contemporaries of Linnæus (Adanson and others42) as capricious and unnecessary restrictions.42Pref. cxxix. clxxii.Many of the names introduced by Linnæus certainly appear fanciful enough. Thus he gives the nameBauhiniato a plant which has leaves in pairs, because the Bauhins were a pair of brothers.Banisteriais the name of a climbing plant in honour of Banister, who travelled among mountains. But such names once established by adequate authority lose all their inconvenience and easily become permanent, and hence the reasonableness of one of the Linnæan rules43:—That as such a perpetuation of the names of persons309by the names of plants is the only honour that botanists have to bestow, it ought to be used with care and caution, and religiously respected.43Phil. Bot.s. 239.[3rd ed. It may serve to show how sensitive botanists are to the allusions contained in such names, that it has been charged against Linnæus, as a proof of malignity towards Buffon, that he changed the name of the genusBuffonia, established by Sauvages, intoBufonia, which suggested a derivation fromBufo, a toad. It appears to be proved that the spelling was not Linnæus’s doing.]Another Linnæan maxim is (Art. 219), that the generic name must be fixed before we attempt to form a specific name; ‘the latter without the former is like the clapper without the bell.’The name of the genus being fixed, the species may be marked (Art. 257) by adding to it ‘a single word taken at will from any quarter;’ that is, it need not involve a description or any essential property of the plant, but may be a casual or arbitrary appellation. Thus the various species ofHieracium44areHieracium Alpinum,H. Halleri,H. Pilosella,H. dubium,H. murorum, &c., where we see how different may be the kind of origin of the words.44Hooker,Fl. Scot.228.Attempts have been made at various times to form the names of species from those of genera in some more symmetrical manner. But these have not been successful, nor are they likely to be so; and we shall venture to propound an axiom in condemnation of such names.AphorismXVI.Numerical names in Classification are bad; and the same may be said of other names of kinds, depending upon any fixed series of notes of order.Withregard to numerical names of kinds, of species for instance, the objections are of this nature. Besides that such names offer nothing for the imagination to take hold of, new discoveries will probably alter the310numeration, and make the names erroneous. Thus, if we call the species of a genus 1, 2, 3, a new species intermediate between 1 and 2, 2 and 3, &c. cannot be put in its place without damaging the numbers.The geological termTrias, lately introduced to designate the group consisting of thethreemembers (Bunter Sandstein, Muschelkalk, and Keuper) becomes improper if, as some geologists hold, two of these members cannot be separated.Objections resembling those which apply to numerical designations of species, apply to other cases of fixed series: for instance, when it has been proposed to mark the species by altering the termination of the genus. Thus Adanson45, denoting a genus by the nameFonna(Lychnidea), conceived he might mark five of its species by altering the last syllable,Fonna,Fonna-e,Fonna-i,Fonna-o,Fonna-u; then others byFonna-ba,Fonna-ka, and so on. This would be liable to the same evils which have been noticed as belonging to the numerical method46.45Pref. clxxvi.46In like manner the names assigned by Mr. Rickman to the successive of styles of Gothic architecture in England,—Early English,Decorated, andPerpendicular,—cannot be replaced by numerical designations,First Pointed,Second Pointed,Third Pointed. For—besides that he who first distinctly establishes classes has the right of naming them, and that Mr. Rickman’s names are really appropriate and significant—these new names would confound all meaning of language. We should not be able to divide Early English, or Decorated, or Perpendicular into sub-styles;—for who could talk ofFirst Second PointedandSecond Second Pointed; and what should we call that pointed style—theTransitionfrom the Norman—which precedes theFirst Pointed?AphorismXVII.In any classificatory science names including more than two steps of the classification may be employed if it be found convenient.Linnæus, in his canons for botanical nomenclature (Art. 212), says that the names of the class and the order are to bemute, while the names of the Genus and Species aresonorous. And accordingly the names311of plants (and the same is true of animals) have in common practice been binary only, consisting of a generic and a specific name. The class and the order have not been admitted to form part of the appellation of the species. Indeed it is easy to see that a name, which must be identical in so many instances as that of an Order would be, would be felt as superfluous and burthensome. Accordingly, Linnæus makes it one of his maxims47, that the name of the Class and Order must not be expressed but understood, and hence, he says, Royen, who tookLiliumfor the name of a Class, rightly rejected this word as a generic name, and substitutedLiriumwith the Greek termination.47Phil. Bot.s. 215.Yet we must not too peremptorily assume such maxims as these to be universal for all classificatory sciences. It is very possible that it may be found advisable to usethreeterms, that of Order, Genus, and Species in designating minerals, as is done in Mohs’s nomenclature, for example,Rhombohedral Calc Haloide,Paratomous Hal Baryte.It is possible also that it may be found useful in the same science (Mineralogy) to mark some of the steps of classification by the termination. Thus it has been proposed to confine the terminationiteto the OrderSilicidesof Naumann, as Apophyllite, Stilbite, Leucite, &c., and to use names of different form in other orders, as TalcSparfor Brennerite, Pyramidal TitaniumOxidefor Octahedrite. Some such method appears to be the most likely to give us a tolerable mineralogical nomenclature.AphorismXVIII.In forming a Terminology, words may be invented when necessary, but they cannot be conveniently borrowed from casual or arbitrary circumstances48.48I may also refer toHist. Sc. Id.b. viii. c. ii. sec. 2, for some remarks on Terminology.Itwill be recollected that Terminology is a language employed for describing objects, Nomenclature, a body312of names of the objects themselves. Thenames, as was stated in the last maxim, may be arbitrary; but thedescriptiveterms must be borrowed from words of suitable meaning in the modern or the classical languages. Thus the whole terminology which Linnæus introduced into botany, is founded upon the received use of Latin words, although he defined their meaning so as to make it precise when it was not so, according to AphorismV.But many of the terms were invented by him and other botanists, asPerianth,Nectary,Pericarp; so many, indeed, as to form, along with the others, a considerable language. Many of the terms which are now become familiar were originally invented by writers on botany. Thus the wordPetal, for one division of the corolla, was introduced by Fabius Columna. The termSepalwas devised by Necker to express each of the divisions of the calyx. And up to the most recent times, new denominations of parts and conditions of parts have been devised by botanists, when they found them necessary, in order to mark important differences or resemblances. Thus the generalReceptacleof the flower, as it is termed by Linnæus, orTorusby Salisbury, is continued into organs which carry the stamina and pistil, or the pistil alone, or the whole flower; this organ has hence been termed49Gonophore,Carpophore, andAnthophore, in these cases.49De Candolle’sTh. El.405.In like manner when Cuvier had ascertained that the lower jaws of Saurians consisted always of six pieces having definite relations of form and position, he gave names to them, and termed them respectively theDental, theAngular, theCoronoid, theArticular, theComplementary, and theOpercularBones.In all these cases, the descriptive terms thus introduced have been significant in their derivation. An attempt to circulate a perfectly arbitrary word as a means of description would probably be unsuccessful. We have, indeed, some examples approaching to arbitrary designations, in the Wernerian names of colours,313which are a part of the terminology of Natural History. Many of these names are borrowed from natural resemblances, asAuricula purple,Apple green,Straw yellow; but the names of others are taken from casual occurrences, mostly, however, such as were already recognized in common language, asPrussian blue,Dutch orange,King’s yellow.The extension of arbitrary names in scientific terminology is by no means to be encouraged. I may mention a case in which it was very properly avoided. When Mr. Faraday’s researches on Voltaic electricity had led him to perceive the great impropriety of the termpoles, as applied to the apparatus, since the processes have not reference to any opposed points, but to two opposite directions of a path, he very suitably wished to substitute for the phrasespositive poleandnegative pole, two words ending inode, fromὅδος, a way. A person who did not see the value of our present maxim, that descriptive terms should be descriptive in their origin, might have proposed words perfectly arbitrary, asAlphode, andBetode: or, if he wished to pay a tribute of respect to the discoverers in this department of science,GalvanodeandVoltaode, But such words would very justly have been rejected by Mr. Faraday, and would hardly have obtained any general currency among men of science.ZincodeandPlatinode, terms derived from the metal which, in one modification of the apparatus, forms what was previously termed the pole, are to be avoided, because in their origin too much is casual; and they are not a good basis for derivative terms. The pole at which the zinc is, is the Anode or Cathode, according as it is associated with different metals. Either theZincodemust sometimes mean the pole at which the Zinc is, and at other times that at which the Zinc is not, or else we must have as many names for poles as there are metals.AnodeandCathode, the terms which Mr. Faraday adopted, were free from these objections; for they refer to a natural standard of the direction of the voltaic current, in a manner which, though perhaps not obvious at first sight, is easily understood and314retained.Anode andCathode, therisingand thesettingway, are the directions which correspond to east and west in that voltaic current to which we must ascribe terrestrial magnetism. And with these words it was easy to connectAnïonandCathïon, to designate the opposite elements which are separated and liberated at the twoElectrodes.AphorismXIX.The meaning of Technical Terms must be fixed by convention, not by casual reference to the ordinary meaning of words.Infixing the meaning of the Technical Terms which form the Terminology of any science, at least of the descriptive Terms, we necessarily fix, at the same time, the perceptions and notions which the Terms are to convey to a hearer. What do we mean byapple-greenorFrench grey? It might, perhaps, be supposed that, in the first example, the termapple, referring to so familiar an object, sufficiently suggests the colour intended. But it may easily be seen that this is not true; for apples are of many different hues of green, and it is only by a conventional selection that we can appropriate the term to one special shade. When this appropriation is once made, the term refers to the sensation, and not to the parts of this term; for these enter into the compound merely as a help to the memory, whether the suggestion be a natural connexion as in ‘apple-green,’ or a casual one as in ‘French grey.’ In order to derive due advantage from technical terms of this kind, they must be associatedimmediatelywith the perception to which they belong; and not connected with it through the vague usages of common language. The memory must retain the sensation; and the technical word must be understood as directly as the most familiar word, and more distinctly. When we find such terms astin-whiteorpinchbeck-brown, the metallic colour so denoted ought to start up in our memory without delay or search.315This, which it is most important to recollect with respect to the simpler properties of bodies, as colour and form, is no less true with respect to more compound notions. In all cases the term is fixed to a peculiar meaning by convention; and the student, in order to use the word, must be completely familiar with the convention, so that he has no need to frame conjectures from the word itself. Such conjectures would always be insecure, and often erroneous. Thus the termpapilionaceous, applied to a flower, is employed to indicate, not only a resemblance to a butterfly, but a resemblance arising from five petals of a certain peculiar shape and arrangement; and even if the resemblance to a butterfly were much stronger than it is in such cases, yet if it were produced in a different way, as, for example, by one petal, or two only, instead of a ‘standard,’ two ‘wings,’ and a ‘keel’ consisting of two parts more or less united into one, we should no longer be justified in speaking of it as a ‘papilionaceous’ flower.The formation of an exact and extensive descriptive language for botany has been executed with a degree of skill and felicity, which, before it was attained, could hardly have been dreamt of as attainable. Every part of a plant has been named; and the form of every part, even the most minute, has had a large assemblage of descriptive terms appropriated to it, by means of which the botanist can convey and receive knowledge of form and structure, as exactly as if each minute part were presented to him vastly magnified. This acquisition was part of the Linnæan Reform, of which we have spoken in theHistory. ‘Tournefort,’ says De Candolle50, ‘appears to have been the first who really perceived the utility of fixing the sense of terms in such a way as always to employ the same word in the same sense, and always to express the same idea by the same word; but it was Linnæus who really created and fixed this botanical language, and this is his fairest claim to glory, for by this fixation of language he has shed clearness and precision over all parts of the science.’50Théor. Élém.p. 327.316It is not necessary here to give any detailed account of the terms of botany. The fundamental ones have been gradually introduced, as the parts of plants were more carefully and minutely examined. Thus the flower was successively distinguished into thecalyx, thecorolla, thestamens, and thepistils: the sections of the corolla were termedpetalsby Columna; those of the calyx were calledsepalsby Necker51. Sometimes terms of greater generality were devised; asperianthto include the calyx and corolla, whether one or both of these were present52;pericarpfor the part inclosing the grain, of whatever kind it be, fruit, nut, pod, &c. And it may easily be imagined that descriptive terms may, by definition and combination, become very numerous and distinct. Thus leaves may be calledpinnatifid53,pinnnatipartite,pinnatisect,pinnatilobate,palmatifid,palmatipartite, &c., and each of these words designates different combinations of the modes and extent of the divisions of the leaf with the divisions of its outline. In some cases arbitrary numerical relations are introduced into the definition: thus a leaf is calledbilobate54when it is divided into two parts by a notch; but if the notch go to the middle of its length, it isbifid; if it go near the base of the leaf, it isbipartite; if to the base, it isbisect. Thus, too, a pod of a cruciferous plant is asilica55if it be four times as long as it is broad, but if it be shorter than this it is asilicula. Such terms being established, the form of the very complex leaf or frond of a fern is exactly conveyed, for example, by the following phrase: ‘fronds rigid pinnate, pinnæ recurved subunilateral pinnatifid, the segments linear undivided or bifid spinuloso-serrate56.’
35Elements of Chem. Phil.p. 46.
These remarks are founded upon distinctions which have no real existence. We cannot separatethingsfrom theirproperties, nor can we consider their properties and analogies in any other way than by havingopinionsabout them. By contrastinganalogieswithopinions, it might appear as if the author maintained that there were certain analogies about which there was no room for erroneous opinions. Yet the analogies of chemical compounds, are, in fact, those points which have been most the subject of difference of opinion, and on which the revolutions of theories have most changed men’s views. As an example of analogies which are still recognized under alterations of theory, the writer gives the relation of a metal to its oxide or calciform state. But this analogy of metallic oxides, as Red Copper or Iron Ore, to Calx, or burnt lime, is very far from being self-evident;—so far indeed, that the recognition of the analogy was a great step in chemicaltheory. The terms which he quotes,oxygenated muriatic acid(and the same may be said ofdephlogisticated marine acid,) if improper, are so not because they involve theory, but because they involve false theory;—not because those who framed them did not endeavour to express analogies, but because they expressed analogies about which they were mistaken. Unconnected names, asmetals,earths,alkalis, are good as thebasisof a systematic nomenclature, but they are not substitutes for such a nomenclature. A systematic nomenclature is an instrument of great utility and power, as the modern history of chemistry has shown. It would be highly unphilosophical to reject298the use of such an instrument, because, in the course of the revolutions of science, we may have to modify, or even to remodel it altogether. Its utility is not by that means destroyed. It has retained, transmitted, and enabled us to reason upon, the doctrines of the earlier theory, so far as they are true; and when this theory is absorbed into a more comprehensive one, (for this, and not its refutation, is the end of a theoryso far asit is true,) the nomenclature is easily translated into that which the new theory introduces. We have seen, in the history of astronomy, how valuable the theory ofepicycleswas, in its time: the nomenclature of the relations of a planet’s orbit, which that theory introduced, was one of Kepler’s resources in discovering theellipticaltheory; and, though now superseded, is still readily intelligible to astronomers.
This is not the place to discuss the reasons for theformof scientific terms; otherwise we might ask, in reference to the objections to the Lavoisierian nomenclature, if such forms asaurumandauraare good to represent the absence or presence of oxygen, why such forms assulphiteandsulphateare not equally good to represent the presence of what we may call a smaller or larger dose of oxygen, so long as the oxygen theory is admitted in its present form; and to indicate still the difference of the same substances, if under any change of theory it should come to be interpreted in a new manner.
But I do not now dwell upon such arguments, my object in this place being to show that terms involving theory are not only allowable, if understood so far as the theory is proved, but of great value, and indeed of indispensable use, in science. The objection to them is inconsistent with the objects of science. If, after all that has been done in chemistry or any other science, we have arrived at no solid knowledge, no permanent truth;—if all that we believe now may be proved to be false to-morrow;—then indeed our opinions and theories are corruptible elements, on which it would be unwise to rest any thing important, and which we might wish to exclude, even from our names. But if299our knowledge has no more security than this, we can find no reason why we should wish at all to have names of things, since the names are needed mainly that we may reason upon and increase our knowledge such as it is. If we are condemned to endless alternations of varying opinions, then, no doubt, our theoretical terms may be a source of confusion; but then, where would be the advantage of their being otherwise? what would be the value of words which should express in a more precise manner opinions equally fleeting? It will perhaps be said, our terms must express facts, not theories: but of this distinction so applied we have repeatedly shown the futility. Theories firmly established are facts. Is it not a fact that the rusting of iron arises from the metal combining with the oxygen of the atmosphere? Is it not a fact that a combination of oxygen and hydrogen produces water? That our terms should expresssuchfacts, is precisely what we are here inculcating.
Our examination of the history of science has led us to a view very different from that which represents it as consisting in the succession of hostile opinions. It is, on the contrary, a progress, in which each step is recognized and employed in the succeeding one. Every theory, so far as it is true, (and all that have prevailed extensively and long, contain a large portion of truth,) is taken up into the theory which succeeds and seems to expel it. All the narrower inductions of the first are included in the more comprehensive generalizations of the second. And this is performed mainly by means of such terms as we are now considering;—terms involving the previous theory. It is by means of such terms, that the truths at first ascertained become so familiar and manageable, that they can be employed as elementary facts in the formation of higher inductions.
These principles must be applied also, though with great caution, and in a temperate manner, even to descriptive language. Thus the mode of describing the forms of crystals adopted by Werner and Romé de l’Isle was to consider an original form, from which other forms are derived bytruncationsof the edges and the300angles. Haüy’s method of describing the same forms, was to consider them as built up of rows of small solids, the angles being determined by thedecrementsof these rows. Both these methods of description involve hypothetical views; and the last was intended to rest on a true physical theory of the constitution of crystals. Both hypotheses are doubtful or false: yet both these methods are good as modes of description: nor is Haüy’s terminology vitiated, if we suppose (as in fact we must suppose in many instances,) that crystalline bodies are not really made up of such small solids. The mode of describing an octahedron of fluor spar, as derived from the cube, by decrements of one row on all the edges, would still be proper and useful as a description, whatever judgment we should form of the material structure of the body. But then, we must consider the solids which are thus introduced into the description as merely hypothetical geometrical forms, serving to determine the angles of the faces. It is in this way alone that Haüy’s nomenclature can now be retained.
In like manner we may admit theoretical views into the descriptive phraseology of other parts of Natural History: and the theoretical terms will replace the obvious images, in proportion as the theory is generally accepted and familiarly applied. For example, in speaking of the Honeysuckle, we may say that the upper leaves areperfoliate, meaning that a single round leaf is perforated by the stalk, or threaded upon it. Here is an image which sufficiently conveys the notion of the form. But it is now generally recognized that this apparent single leaf is, in fact, two opposite leaves joined together at their bases. If this were doubted, it may be proved by comparing the upper leaves with the lower, which are really separate and opposite. Hence the termconnateis applied to these conjoined opposite leaves, implying that they grow together; or they are calledconnato-perfoliate. Again; formerly the corolla was calledmonopetalousorpolypetalous, as it consisted of one part or of several: but it is now agreed among botanists that those corollas which301appear to consist of a single part, are, in fact, composed of several soldered together; hence the termgamopetalousis now employed (by De Candolle and his followers) instead of monopetalous36.
36On this subject, see Illiger,Versuch einer Systematischen Vollständigen Terminologie für das Thierreich und Pflanzenreich(1810). De Candolle,Théorie Élémentaire de la Botanique.
In this way the language of Natural History not only expresses, but inevitably implies, general laws of nature; and words are thus fitted to aid the progress of knowledge in this, as in other provinces of science.
AphorismXII.
If terms are systematically good, they are not to be rejected because they are etymologically inaccurate.
Termsbelonging to a system are defined, not by the meaning of their radical words, but by their place in the system. That they should be appropriate in their signification, aids the processes of introducing and remembering them, and should therefore be carefully attended to by those who invent and establish them; but this once done, no objections founded upon their etymological import are of any material weight. We find no inconvenience in the circumstance thatgeometrymeans the measuring of the earth, that the nameporphyryis applied to many rocks which have no fiery spots, as the word implies, andooliteto strata which have no roelike structure. In like manner, if the termpœcilitewere already generally received, as the name of a certain group of strata, it would be no valid ground for quarrelling with it, that this group was not always variegated in colour, or that other groups were equally variegated: although undoubtedly inintroducingsuch a term, care should be taken to make it as distinctive as possible. It often happens, as we have seen, that by the natural progress of changes in language, a word is steadily confirmed in a sense quite different from its etymological import. But though302we may accept such instances, we must not wantonly attempt to imitate them. I say, not wantonly: for if the progress of scientific identification compel us to follow any class of objects into circumstances where the derivation of the term is inapplicable, we may still consider the term as an unmeaning sound, or rather an historical symbol, expressing a certain member of our system. Thus if, in following the course of themountainorcarboniferouslimestone, we find that in Ireland it does not form mountains nor contain coal, we should act unwisely in breaking down the nomenclature in which our systematic relations are already expressed, in order to gain, in a particular case, a propriety of language which has no scientific value.
All attempts to act upon the maxim opposite to this, and to make our scientific names properly descriptive of the objects, have failed and must fail. For the marks which really distinguish the natural classes of objects, are by no means obvious. The discovery of them is one of the most important steps in science; and when they are discovered, they are constantly liable to exceptions, because they do not contain the essential differences of the classes. The natural orderUmbellatæ, in order to be a natural order, must contain some plants which have not umbels, asEryngium37. ‘In such cases,’ said Linnæus, ‘it is of small import what you call the order, if you take a proper series of plants, and give it some name which is clearly understood to apply to the plants you have associated.’ ‘I have,’ he adds, ‘followed the rule of borrowing the nameà fortiori, from the principal feature.’
37SeeHist. Ind. Sc.b. xvi. c. iv. sect. 5.
The distinction of crystals into systems according to the degree of symmetry which obtains in them, has been explained elsewhere. Two of these systems, of which the relation as to symmetry might be expressed by saying that one issquare pyramidaland the otheroblong pyramidal, or the firstsquare prismaticand the secondoblong prismatic, are termed by Mohs, the first,Pyramidal, and the secondPrismatic. And it may303be doubted whether it is worth while to invent other terms, though these are thus defective in characteristic significance. As an example of a needless rejection of old terms in virtue of a supposed impropriety in their meaning, I may mention the attempt made in the last edition of Haüy’sMineralogy, to substituteautopsideandheteropsideformetallicandunmetallic. It was supposed to be proved that all bodies have a metal for their basis; and hence it was wished to avoid the termunmetallic. But the wordsmetallicandunmetallicmay mean that mineralsseemmetallic and unmetallic, just as well as if they contained the elementopsideto imply this seeming. The old names express all that the new express, and with more simplicity, and therefore should not be disturbed.
The maxim on which we are now insisting, that we are not to be too scrupulous about the etymology of scientific terms, may, at first sight, appear to be at variance with ourFourthAphorism, that words used technically are to retain their common meaning as far as possible. But it must be recollected, that in the Fourth Aphorism we spoke ofcommonwordsappropriatedas technical terms; we here speak of wordsconstructedfor scientific purposes. And although it is, perhaps, impossible to draw a broad line between these two classes of terms, still the rule of propriety may be stated thus: In technical terms, deviations from the usual meaning of words are bad in proportion as the words are more familiar in our own language. Thus we may apply the termCirrusto a cloud composed of filaments, even if these filaments are straight; but to call such a cloud aCurl cloudwould be much more harsh.
Since the names of things, and of classes of things, when constructed so as to involve a description, are constantly liable to become bad, the natural classes shifting away from the descriptive marks thus prematurely and casually adopted, I venture to lay down the following maxim.304
AphorismXIII.
The fundamental terms of a system of Nomenclature may be conveniently borrowed from casual or arbitrary circumstances.
Forinstance, the names of plants, of minerals, and of geological strata, may be taken from the places where they occur conspicuously or in a distinct form; asParietaria,Parnassia,Chalcedony,Arragonite,Siluriansystem,Purbecklimestone. These names may be considered as at first supplying standards of reference; for in order to ascertain whether any rock bePurbecklimestone, we might compare it with the rocks in the Isle of Purbeck. But this reference to a local standard is of authority only till the place of the object in the system, and its distinctive marks, are ascertained. It would not vitiate the above names, if it were found that theParnassiadoes not grow on Parnassus; thatChalcedonyis not found in Chalcedon; or even thatArragoniteno longer occurs in Arragon; for it is now firmly established as a mineral species. Even in geology such a reference is arbitrary, and may be superseded, or at least modified, by a more systematic determination.Alpinelimestone is no longer accepted as a satisfactory designation of a rock, now that we know the limestone of the Alps to be of various ages.
Again, names of persons, either casually connected with the object, or arbitrarily applied to it, may be employed as designations. This has been done most copiously in botany, as for example,Nicotiana,Dahlia,Fuchsia,Jungermannia,Lonicera. And Linnæus has laid down rules for restricting this mode of perpetuating the memory of men, in the names of plants. Those generic names, he says38, which have been constructed to preserve the memory of persons who have deserved well of botany, are to be religiously retained. This, he adds, is the sole and supreme reward of the botanist’s labours, and must be carefully guarded and305scrupulously bestowed, as an encouragement and an honour. Still more arbitrary are the terms borrowed from the names of the gods and goddesses, heroes and heroines of antiquity, to designate new genera in those departments of natural history in which so many have been discovered in recent times as to weary out all attempts at descriptive nomenclature. Cuvier has countenanced this method. ‘I have had to frame many new names of genera and sub-genera,’ he says39, ‘for the sub-genera which I have established were so numerous and various, that the memory is not satisfied with numerical indications. These I have chosen either so as to indicate some character, or among the usual denominations, which I have latinized, or finally, after the example of Linnæus, among the names of mythology, which are in general agreeable to the ear, and which are far from being exhausted.’
38Phil. Bot.241.
39Règne An.p. 16.
This mode of framing names from the names of persons to whom it was intended to do honour, has been employed also in the mathematical and chemical sciences; but such names have rarely obtained any permanence, except when they recorded an inventor or discoverer. Some of the constellations, indeed, have retained such appellations, asBerenice’s Hair; and the new star which shone out in the time of Cæsar, would probably have retained the name given to it, of theJulian Star, if it had not disappeared again soon after. In the map of the Moon, almost all the parts have had such names imposed upon them by those who have constructed such maps, and these names have very properly been retained. But the names of new planets and satellites thus suggested have not been generally accepted; as theMediceanstars, the name employed by Galileo for the satellites of Jupiter; theGeorgium Sidus, the appellation proposed by Herschel for Uranus when first discovered40; CeresFerdinandea,306the name which Piazzi wished to impose on the small planet Ceres. The names given to astronomical Tables by the astronomers who constructed them have been most steadily adhered to, being indeed names of books, and not of natural objects. Thus there were theIlchanic, theAlphonsine, theRudolphine, theCarolinianTables. Comets which have been ascertained to be periodical, have very properly had assigned to them the name of the person who established this point; and of these we have thus,Halley’s,Encke’s Comet, andBiela’sorGambart’s Comet.
40In this case, the nameUranus, selected with a view to symmetry according to the mythological order of descent of the persons (Uranus,Saturn,Jupiter,Mars) was adopted by astronomers in general, though not proposed or sanctioned by the discoverer of the new planet. In the cases of the smaller planets,Ceres,Pallas,Juno, andVesta, the names were given either by the discoverer, or with his sanction. Following this rule, Bessel gave the name ofAstræato a new planet discovered in the same region by Mr. Hencke, as mentioned in the additions to book vii. of theHistory(2nd Ed.). Following the same rule, and adhering as much as possible to mythological connexion, the astronomers of Europe have with the sanction of M. Le Verrier, given the name ofNeptuneto the planet revolving beyond Uranus, and discovered in consequence of his announcement of its probable existence, which had been inferred by Mr. Adams and him (calculating in ignorance of each other’s purpose) from the perturbations of Uranus; as I have stated in the Additions to the Third Edition of theHistory.
In the case of discoveries in science or inventions of apparatus, the name of the inventor is very properly employed as the designation. Thus we have theTorricellianVacuum, theVoltaicPile,Fahrenheit’sThermometer. And in the same manner with regard to laws of nature, we haveKepler’sLaws,BoyleorMariotte’slaw of the elasticity of air,Huyghens’slaw of double refraction,Newton’sscale of colours.Descartes’law of refraction is an unjust appellation; for the discovery of the law of sines was made by Snell. In deductive mathematics, where the invention of a theorem is generally a more definite step than an induction, this mode of designation is more common, asDemoivre’sTheorem,Maclaurin’sTheorem,Lagrange’sTheorem,EulerianIntegrals.
In theHistory of Science41I have remarked that in the discovery of what is termed galvanism, Volta’s307office was of a higher and more philosophical kind than that of Galvani; and I have, on this account, urged the propriety of employing the termvoltaic, rather thangalvanicelectricity. I may add that the electricity of the common machine is often placed in contrast with this, and appears to require an express name. Mr. Faraday calls itcommonormachineelectricity; but I think thatfranklinicelectricity would form a more natural correspondence withvoltaic, and would be well justified by Franklin’s place in the history of that part of the subject.
41b. xiii. c. 1.
AphorismXIV.
The Binary Method of Nomenclature(Names by Genus and Species)is the most convenient hitherto employed in Classification.
Thenumber of species in every province of Natural History is so vast that we cannot distinguish them and record the distinctions without some artifice. The known species of plants, for instance, were 10,000 in the time of Linnæus, and are now probably 60,000. It would be useless to endeavour to frame and employ separate names for each of these species.
The division of the objects into a subordinated system of classification enables us to introduce a Nomenclature which does not require this enormous number of names. The artifice employed is, to name a specimen by means of two (or it might be more) steps of the successive division. Thus in Botany, each of the Genera has its name, and the species are marked by the addition of some epithet to the name of the genus. In this manner about 1,700 Generic Names, with a moderate number of Specific Names, were found by Linnæus sufficient to designate with precision all the species of vegetables known at his time. And thisBinary Methodof Nomenclature has been found so convenient, that it has been universally adopted in every other department of the Natural History of organized beings.308
Many other modes of Nomenclature have been tried, but no other has at all taken root. Linnæus himself appears at first to have intended marking each species by the Generic Name, accompanied by a characteristic Descriptive Phrase; and to have proposed the employment of aTrivialSpecific Name, as he termed it, only as a method of occasional convenience. The use of these trivial names, however, has become universal, as we have said; and is by many persons considered the greatest improvement introduced at the Linnæan reform.
AphorismXV.
The Maxims of Linnæus concerning the Names to be used in Botany, (Philosophia Botanica, Nomina. Sections 210 to 255)are good examples of Aphorisms on this subject.
BothLinnæus and other writers (as Adanson) have given many maxims with a view of regulating the selection of generic and specific names. The maxims of Linnæus were intended as much as possible to exclude barbarism and confusion, and have, upon the whole, been generally adopted.
These canons, and the sagacious modesty of great botanists, like Robert Brown, in conforming to them, have kept the majority of good botanists within salutary limits; though many of these canons were objected to by the contemporaries of Linnæus (Adanson and others42) as capricious and unnecessary restrictions.
42Pref. cxxix. clxxii.
Many of the names introduced by Linnæus certainly appear fanciful enough. Thus he gives the nameBauhiniato a plant which has leaves in pairs, because the Bauhins were a pair of brothers.Banisteriais the name of a climbing plant in honour of Banister, who travelled among mountains. But such names once established by adequate authority lose all their inconvenience and easily become permanent, and hence the reasonableness of one of the Linnæan rules43:—That as such a perpetuation of the names of persons309by the names of plants is the only honour that botanists have to bestow, it ought to be used with care and caution, and religiously respected.
43Phil. Bot.s. 239.
[3rd ed. It may serve to show how sensitive botanists are to the allusions contained in such names, that it has been charged against Linnæus, as a proof of malignity towards Buffon, that he changed the name of the genusBuffonia, established by Sauvages, intoBufonia, which suggested a derivation fromBufo, a toad. It appears to be proved that the spelling was not Linnæus’s doing.]
Another Linnæan maxim is (Art. 219), that the generic name must be fixed before we attempt to form a specific name; ‘the latter without the former is like the clapper without the bell.’
The name of the genus being fixed, the species may be marked (Art. 257) by adding to it ‘a single word taken at will from any quarter;’ that is, it need not involve a description or any essential property of the plant, but may be a casual or arbitrary appellation. Thus the various species ofHieracium44areHieracium Alpinum,H. Halleri,H. Pilosella,H. dubium,H. murorum, &c., where we see how different may be the kind of origin of the words.
44Hooker,Fl. Scot.228.
Attempts have been made at various times to form the names of species from those of genera in some more symmetrical manner. But these have not been successful, nor are they likely to be so; and we shall venture to propound an axiom in condemnation of such names.
AphorismXVI.
Numerical names in Classification are bad; and the same may be said of other names of kinds, depending upon any fixed series of notes of order.
Withregard to numerical names of kinds, of species for instance, the objections are of this nature. Besides that such names offer nothing for the imagination to take hold of, new discoveries will probably alter the310numeration, and make the names erroneous. Thus, if we call the species of a genus 1, 2, 3, a new species intermediate between 1 and 2, 2 and 3, &c. cannot be put in its place without damaging the numbers.
The geological termTrias, lately introduced to designate the group consisting of thethreemembers (Bunter Sandstein, Muschelkalk, and Keuper) becomes improper if, as some geologists hold, two of these members cannot be separated.
Objections resembling those which apply to numerical designations of species, apply to other cases of fixed series: for instance, when it has been proposed to mark the species by altering the termination of the genus. Thus Adanson45, denoting a genus by the nameFonna(Lychnidea), conceived he might mark five of its species by altering the last syllable,Fonna,Fonna-e,Fonna-i,Fonna-o,Fonna-u; then others byFonna-ba,Fonna-ka, and so on. This would be liable to the same evils which have been noticed as belonging to the numerical method46.
45Pref. clxxvi.
46In like manner the names assigned by Mr. Rickman to the successive of styles of Gothic architecture in England,—Early English,Decorated, andPerpendicular,—cannot be replaced by numerical designations,First Pointed,Second Pointed,Third Pointed. For—besides that he who first distinctly establishes classes has the right of naming them, and that Mr. Rickman’s names are really appropriate and significant—these new names would confound all meaning of language. We should not be able to divide Early English, or Decorated, or Perpendicular into sub-styles;—for who could talk ofFirst Second PointedandSecond Second Pointed; and what should we call that pointed style—theTransitionfrom the Norman—which precedes theFirst Pointed?
AphorismXVII.
In any classificatory science names including more than two steps of the classification may be employed if it be found convenient.
Linnæus, in his canons for botanical nomenclature (Art. 212), says that the names of the class and the order are to bemute, while the names of the Genus and Species aresonorous. And accordingly the names311of plants (and the same is true of animals) have in common practice been binary only, consisting of a generic and a specific name. The class and the order have not been admitted to form part of the appellation of the species. Indeed it is easy to see that a name, which must be identical in so many instances as that of an Order would be, would be felt as superfluous and burthensome. Accordingly, Linnæus makes it one of his maxims47, that the name of the Class and Order must not be expressed but understood, and hence, he says, Royen, who tookLiliumfor the name of a Class, rightly rejected this word as a generic name, and substitutedLiriumwith the Greek termination.
47Phil. Bot.s. 215.
Yet we must not too peremptorily assume such maxims as these to be universal for all classificatory sciences. It is very possible that it may be found advisable to usethreeterms, that of Order, Genus, and Species in designating minerals, as is done in Mohs’s nomenclature, for example,Rhombohedral Calc Haloide,Paratomous Hal Baryte.
It is possible also that it may be found useful in the same science (Mineralogy) to mark some of the steps of classification by the termination. Thus it has been proposed to confine the terminationiteto the OrderSilicidesof Naumann, as Apophyllite, Stilbite, Leucite, &c., and to use names of different form in other orders, as TalcSparfor Brennerite, Pyramidal TitaniumOxidefor Octahedrite. Some such method appears to be the most likely to give us a tolerable mineralogical nomenclature.
AphorismXVIII.
In forming a Terminology, words may be invented when necessary, but they cannot be conveniently borrowed from casual or arbitrary circumstances48.
48I may also refer toHist. Sc. Id.b. viii. c. ii. sec. 2, for some remarks on Terminology.
Itwill be recollected that Terminology is a language employed for describing objects, Nomenclature, a body312of names of the objects themselves. Thenames, as was stated in the last maxim, may be arbitrary; but thedescriptiveterms must be borrowed from words of suitable meaning in the modern or the classical languages. Thus the whole terminology which Linnæus introduced into botany, is founded upon the received use of Latin words, although he defined their meaning so as to make it precise when it was not so, according to AphorismV.But many of the terms were invented by him and other botanists, asPerianth,Nectary,Pericarp; so many, indeed, as to form, along with the others, a considerable language. Many of the terms which are now become familiar were originally invented by writers on botany. Thus the wordPetal, for one division of the corolla, was introduced by Fabius Columna. The termSepalwas devised by Necker to express each of the divisions of the calyx. And up to the most recent times, new denominations of parts and conditions of parts have been devised by botanists, when they found them necessary, in order to mark important differences or resemblances. Thus the generalReceptacleof the flower, as it is termed by Linnæus, orTorusby Salisbury, is continued into organs which carry the stamina and pistil, or the pistil alone, or the whole flower; this organ has hence been termed49Gonophore,Carpophore, andAnthophore, in these cases.
49De Candolle’sTh. El.405.
In like manner when Cuvier had ascertained that the lower jaws of Saurians consisted always of six pieces having definite relations of form and position, he gave names to them, and termed them respectively theDental, theAngular, theCoronoid, theArticular, theComplementary, and theOpercularBones.
In all these cases, the descriptive terms thus introduced have been significant in their derivation. An attempt to circulate a perfectly arbitrary word as a means of description would probably be unsuccessful. We have, indeed, some examples approaching to arbitrary designations, in the Wernerian names of colours,313which are a part of the terminology of Natural History. Many of these names are borrowed from natural resemblances, asAuricula purple,Apple green,Straw yellow; but the names of others are taken from casual occurrences, mostly, however, such as were already recognized in common language, asPrussian blue,Dutch orange,King’s yellow.
The extension of arbitrary names in scientific terminology is by no means to be encouraged. I may mention a case in which it was very properly avoided. When Mr. Faraday’s researches on Voltaic electricity had led him to perceive the great impropriety of the termpoles, as applied to the apparatus, since the processes have not reference to any opposed points, but to two opposite directions of a path, he very suitably wished to substitute for the phrasespositive poleandnegative pole, two words ending inode, fromὅδος, a way. A person who did not see the value of our present maxim, that descriptive terms should be descriptive in their origin, might have proposed words perfectly arbitrary, asAlphode, andBetode: or, if he wished to pay a tribute of respect to the discoverers in this department of science,GalvanodeandVoltaode, But such words would very justly have been rejected by Mr. Faraday, and would hardly have obtained any general currency among men of science.ZincodeandPlatinode, terms derived from the metal which, in one modification of the apparatus, forms what was previously termed the pole, are to be avoided, because in their origin too much is casual; and they are not a good basis for derivative terms. The pole at which the zinc is, is the Anode or Cathode, according as it is associated with different metals. Either theZincodemust sometimes mean the pole at which the Zinc is, and at other times that at which the Zinc is not, or else we must have as many names for poles as there are metals.AnodeandCathode, the terms which Mr. Faraday adopted, were free from these objections; for they refer to a natural standard of the direction of the voltaic current, in a manner which, though perhaps not obvious at first sight, is easily understood and314retained.Anode andCathode, therisingand thesettingway, are the directions which correspond to east and west in that voltaic current to which we must ascribe terrestrial magnetism. And with these words it was easy to connectAnïonandCathïon, to designate the opposite elements which are separated and liberated at the twoElectrodes.
AphorismXIX.
The meaning of Technical Terms must be fixed by convention, not by casual reference to the ordinary meaning of words.
Infixing the meaning of the Technical Terms which form the Terminology of any science, at least of the descriptive Terms, we necessarily fix, at the same time, the perceptions and notions which the Terms are to convey to a hearer. What do we mean byapple-greenorFrench grey? It might, perhaps, be supposed that, in the first example, the termapple, referring to so familiar an object, sufficiently suggests the colour intended. But it may easily be seen that this is not true; for apples are of many different hues of green, and it is only by a conventional selection that we can appropriate the term to one special shade. When this appropriation is once made, the term refers to the sensation, and not to the parts of this term; for these enter into the compound merely as a help to the memory, whether the suggestion be a natural connexion as in ‘apple-green,’ or a casual one as in ‘French grey.’ In order to derive due advantage from technical terms of this kind, they must be associatedimmediatelywith the perception to which they belong; and not connected with it through the vague usages of common language. The memory must retain the sensation; and the technical word must be understood as directly as the most familiar word, and more distinctly. When we find such terms astin-whiteorpinchbeck-brown, the metallic colour so denoted ought to start up in our memory without delay or search.315
This, which it is most important to recollect with respect to the simpler properties of bodies, as colour and form, is no less true with respect to more compound notions. In all cases the term is fixed to a peculiar meaning by convention; and the student, in order to use the word, must be completely familiar with the convention, so that he has no need to frame conjectures from the word itself. Such conjectures would always be insecure, and often erroneous. Thus the termpapilionaceous, applied to a flower, is employed to indicate, not only a resemblance to a butterfly, but a resemblance arising from five petals of a certain peculiar shape and arrangement; and even if the resemblance to a butterfly were much stronger than it is in such cases, yet if it were produced in a different way, as, for example, by one petal, or two only, instead of a ‘standard,’ two ‘wings,’ and a ‘keel’ consisting of two parts more or less united into one, we should no longer be justified in speaking of it as a ‘papilionaceous’ flower.
The formation of an exact and extensive descriptive language for botany has been executed with a degree of skill and felicity, which, before it was attained, could hardly have been dreamt of as attainable. Every part of a plant has been named; and the form of every part, even the most minute, has had a large assemblage of descriptive terms appropriated to it, by means of which the botanist can convey and receive knowledge of form and structure, as exactly as if each minute part were presented to him vastly magnified. This acquisition was part of the Linnæan Reform, of which we have spoken in theHistory. ‘Tournefort,’ says De Candolle50, ‘appears to have been the first who really perceived the utility of fixing the sense of terms in such a way as always to employ the same word in the same sense, and always to express the same idea by the same word; but it was Linnæus who really created and fixed this botanical language, and this is his fairest claim to glory, for by this fixation of language he has shed clearness and precision over all parts of the science.’
50Théor. Élém.p. 327.316
It is not necessary here to give any detailed account of the terms of botany. The fundamental ones have been gradually introduced, as the parts of plants were more carefully and minutely examined. Thus the flower was successively distinguished into thecalyx, thecorolla, thestamens, and thepistils: the sections of the corolla were termedpetalsby Columna; those of the calyx were calledsepalsby Necker51. Sometimes terms of greater generality were devised; asperianthto include the calyx and corolla, whether one or both of these were present52;pericarpfor the part inclosing the grain, of whatever kind it be, fruit, nut, pod, &c. And it may easily be imagined that descriptive terms may, by definition and combination, become very numerous and distinct. Thus leaves may be calledpinnatifid53,pinnnatipartite,pinnatisect,pinnatilobate,palmatifid,palmatipartite, &c., and each of these words designates different combinations of the modes and extent of the divisions of the leaf with the divisions of its outline. In some cases arbitrary numerical relations are introduced into the definition: thus a leaf is calledbilobate54when it is divided into two parts by a notch; but if the notch go to the middle of its length, it isbifid; if it go near the base of the leaf, it isbipartite; if to the base, it isbisect. Thus, too, a pod of a cruciferous plant is asilica55if it be four times as long as it is broad, but if it be shorter than this it is asilicula. Such terms being established, the form of the very complex leaf or frond of a fern is exactly conveyed, for example, by the following phrase: ‘fronds rigid pinnate, pinnæ recurved subunilateral pinnatifid, the segments linear undivided or bifid spinuloso-serrate56.’