This condition of being, suggested the notion of Protozoa, or first animals, in the same way that the purely cellular plants, that is, each individual, consisting of a single cell, gave the idea ofProtophyta, or first plants. Mr. Kirby thus expresses himself on this subject: "The first plants, and the first animals, are scarcely more than animated molecules, and appear analogues of each other; and those above them in each kingdom represent jointed fibrils."
Admitting, then, that animals as well as plants exist in the form of simple cells, and that their multiplication proceeds apparently upon the same principle in each, it is nevertheless abundantly manifest, that the cellular form of perfect individuals is infinitely more numerous in the vegetable than in the animal kingdom.
From the mosses downwards to the fungi, the whole structure of the plants consists of an aggregation of cells, more or less in number and complicate arrangement, until, through a variety of gradations, we reach the single cell as a perfect individual.
It is rather remarkable, that the lower forms of vegetables and animals seem to derive their nutriment from matter of a similar kind; and though the office of plants is as a rule, to convert inorganic into organized matter, it appears that some of the fungi may live as animals do on organic matter when in a state of solution. This, however, is uncertain; for we do not know what are the first signs of decomposition in organized bodies, and for aught we can tell, it may be perpetually going on; so far as the disengagement of carbon from the system is concerned, this is certain; but whether the nitrogenous compounds also are subject to a resolution into their elements in the living body, is another question, and not so easy of solution. The partially decomposed elements of animal structures are, however, particularly adapted for the nutrition of the lower forms of vegetation; it is, indeed, from the decaying organic matters that the fungi derive, it may be said, their entire food.
SECTION III.
SKETCH OF THE PHYSIOLOGY AND PATHOLOGY OF PLANTS AND ANIMALS.
Animals and plants depend for their existence upon a nutritive fluid, which permeates their structure; it is the element from which all their secretions are formed, and their organs are nourished.
The food of animals is composed of previously organized matters, and is conveyed into a reservoir called a stomach, where it undergoes a process of solution, previously to entering the circulation. At this period, the animal and the plant again present points of resemblance, the lymphatics or absorbent vessels take up the products of digestion, and convey them to the blood-vessels, where mingling with the current of the blood, they are conveyed to the lungs, there to undergo a process of oxygenation before they become fitted for the renovation of the tissues of the body. Such is the nature of the food of man, that it contains all the elements necessary and adapted for transformation into bone, muscle, brain, and parenchyma, as well as the other tissues of the body; besides other elementary matters, which, though they form a very insignificant portion ofanimal textures, from their constant presence in the vital fluid, evidently perform some important offices in the general economy of life; they are partly, perhaps, occupied in forming constituents of secretions.
Plants do not require a stomach,—the humus or soil to which they are fixed is the laboratory, where the nutritive matter is prepared in a state fit for absorption by the spongioles of their roots, and these correspond to the lymphatics of animals; after being taken up by the spongioles, this new fluid mingles with the sap, and passes to the leaves or breathing apparatus of plants, where carbonic acid gas combines with the crude vital liquid, and converts it into a condition fit for all the offices to be performed by the plant: viz. the growth of tissues, and the elaboration of secretions.
The tissues, however, of plants, though more simple in their nature, present a much more varied character than those of animals, when the different species are compared.
The bones of animals which give them their form, are invariably constituted of phosphate and carbonate of lime, deposited in a matrix of gluten; muscle, nerve, brain, tendons, and ligaments, have nearly, if not completely, an identical composition throughout the whole range of the animal kingdom: their secretions, however, vary much more considerably, as also do the secretions of vegetables. But vegetable tissue may contain, as in the stems ofgrasses, a considerable amount of silex, and some notable quantity of sulphur, and so essential to their existence is the former element, that they cannot live without its presence in the soil, and also with it an alkali, to render it soluble. A large amount of soda, is an invariable attendant upon the structure of marine plants, as potash is of those growing on the land.
Thus, whether we regard the health of animals, or vegetables, we discover, that besides the matters which are absolutely indispensable for the nutriment of the tissues which undergo rapid transformation, those of a more permanent and durable nature require in an almost insensible degree, a restitution of elements; and though not apparently absolutely necessary to preserve vitality in the being, yet have so marked an influence over it, as to indicate an extensive bearing of eachindividualpart, on the whole associated entity.
The elementary tissues of both kingdoms have been traced, in whatever form they may be found, to a cellular origin. The minutest vegetable germ, is a cell containing a granular matter within it, and even man himself, in his embryonic state, may be represented as an insignificant point in the realms of space; and might be placed side by side with the smallest particle of living matter, without suffering by the comparison.
The laws by which the development of these elementary cells is regulated, so that each advancesto its limit, and fulfils its destination, is one of those inscrutable and overwhelming mysteries of nature, which leads the admirer of creation on and on into the abyss of the future, and fills his soul with aspirations for that time, when the veil of ignorance shall be withdrawn. But this is not my subject.
The organization of the two animated kingdoms, is then regulated by definite laws, and all matter, whether acting upon them as agents of nutrition or destruction, are equally under their dominion; to investigate and to endeavour to fathom some of these laws, is the aim I have in view.
The sap is to the plant, what the blood is to the animal,—the elements of nutrition and secretion are contained in it, and whatever interferes with its normal constitution by subtracting from, or adding to it, deteriorates its qualities, and retards or accelerates the functions of the individual. Excess or deficiency of the natural elements may also be a source of disturbance; if carbonic acid be too abundantly liberated in the soil, as Dr. Lindley expresses it, "plants become gorged;" and if, on the other hand, the elimination be too slow, they become starved. It has been also shewn, that plants though they give out oxygen from their leaves, do not throw it off as animals do carbonic acid from their lungs; but that this arises as a result of digestion, and the fixation of carbon in the system, and that they really respire oxygen asanimals do, and give off carbonic acid, both by day and night.
That light is the stimulant of the digestive functions, and that, therefore, during the day, the amount of oxygen thrown off, far exceeds the amount of carbonic acid liberated during the same period.
The great and important distinction between animals and plants is, that the former possess a nervous system, by which they are subject to a very extended series of psychological relations; it is in these chiefly, if not entirely, that we are to look for the distinctive and well-marked differences of diseased action. In animals there are special media of communication between the sources of dynamic power, and the parts upon which the force is exercised: and again, a return communication exists, which conveys impressions to the source of power, and to use a simple comparison, a system of telegraphing is in incessant and watchful operation. This force is influenced and modified in its action, when exercised in the regulation of nutrition, growth, and reproduction of tissues, by the passions and emotions of the mind. All the secretions and functions of the body are more or less susceptible of being accelerated, retarded or modified by the psychical relations of mind and matter. Though we are apt to imagine that in man alone, these phenomena obtain much importance—there can be but little doubt, that wherever anervous system exists, whether in the form of aggregated or diffused ganglia, the interdependence of force and organization, each upon the other, bears a certain and definite physiological comparison; the more aggregated the ganglia, the more close, intimate, and extensive the psychical connexions, and the gradations pass downwards, until they appear to be lost on the confines of the vegetable kingdom.
The diseases of plants and animals deserve a more careful comparison than, I think, has hitherto been bestowed upon them.[58]If the study of physiology, or an enquiry into the laws which regulate the functions of living beings in a state of health, has been materially aided by the intimate knowledge of vegetable physiology, which, from the simple structure of plants, so favours the experiments of the student, there is every reason to suppose that vegetable pathology may also lead us to an equally important and useful result.
It is quite certain, that if a healthy seed, or leaf-bud, be placed in such a situation, that, according to the laws known, it will in all likelihood germinate, if all the elements for its sustenance exist in the soil, and the temperature and hygrometriccondition of the atmosphere are adapted to it, a healthy plant will be the result. Light, heat, moisture, and soil are therefore to be considered as the agents required to exist in a certain balance, or proportion, in reference to the health or power of vitality of the plant. Within a certain amount of variation, health may persist in virtue of the power of selection, which appertains to the spongioles of the root in absorbing nutriment; and also as regards light, from the tendency which most plants have to accommodate themselves to any deficiency of this element, by presenting their leafy expansion in that direction where the most of its influence may be obtained. But beyond a certain limit an unhealthy condition sets in. If the soil contain not the inorganic elements, which are absolutely indispensable for the tissues of the plant, or even if they be there and not in a state to be absorbed, a dwindling and degeneration ensue; if light be deficient in quantity, pallor, feebleness, and elongation of tissue follow, with more fluidity and general softness of texture. These conditions of plants have their analogues in the ill-fed and ill-nourished children in some of our manufacturing districts; they are stunted and diseased. Transport a healthy country lad, with the bloom of health on his cheek, from his native hills and valleys, or woods and fields, to the stool behind a desk for eight hours a day, in a narrow street in any city, where the rays of the sun rarely penetrate, it will not be long beforethe skin of the animal and the cuticle of the plant may be submitted for comparison, when both will testify to the importance of the solar rays, as an indispensable agent in supporting the normal processes of organic life. So far common observation is competent to a solution of the facts; but beyond this we come to the enquiry, what resemblances are there in the early conditions of plants and animals. Each originates from nucleated cells, endowed by the All-seeing Power with a blind impulse of progressive development; the most simple cell of a vegetable multiplies itself by a generation of new cells within it, when the parent dies, and liberates the offspring. Here progression is simply multiplication; it is, as it were, progression in length only. The original cell, however, of animals, which is styled the germinal vesicle, extends or becomes developed into dissimilar parts; and whatever may be the variety, all alike proceed from the original germ cell, and thetout ensembleof parts constitutes the one and indivisible whole; in this instance there is addition besides multiplication, tissues and organs are added in all variety, until the maximum of organic development is attained in the wonderful being, man.
Yet how many points of resemblance are there between the vegetable cell and the fully developed human being, in a physiological and pathological point of view. There must be nourishment to sustain both; both require a certain amount of lightand heat for their growth and increase, and are dependent upon various unknown causes for active and healthy existence; and when a certain time has expired, all alike return to a condition, in which the particles composing them are subject only to the dominion of the laws which preside over inorganic matter.
But during the existence of plants and animals, we discover other features of comparison; plants, as well as animals, are liable to disease; they are subject to functional and organic affections. The former, among plants, are usually traceable to atmospheric vicissitudes or irregularities, changes of situation, &c.; and in man to irregularities of diet, and mental and bodily excesses, as well as to atmospheric vicissitudes.[59]
The organic diseases of plants and animals depend upon a repetition, or continuance, of functional derangement. As a consequence of this, the nutrition and reproduction of tissues lose their normal and definite character, wherefrom an indefinite and abnormal result is obtained. There is a limit to abnormal productions, and they are apparentlysubject to laws, though not yet understood. In animals, they may be either excessive development of natural tissue in natural localities, as obesity and fatty tumours; they may be natural products in unnatural situations, as fatty degenerations of muscular tissue; or altogether new and unnatural products, as tubercle and cancer.
In plants, from their greater simplicity of structure, organic affections are perhaps entirely limited to the two first forms of animal organic disease; viz. to undue development of tissue in natural situations, and to the formation of natural tissue in parts of a plant where they are not usually found in a state of nature. The variety of excrescences seen on the stems, branches, and twigs of plants, may be given as instances of the former; and the conversion of stamina into petals, as in double flowers, as an instance of the latter.
We derive our sustenance from vegetables, and they from us; they produce for us the soothing opiate and the deadly strychnia; we for them the animating ammonia, and the distortions and sterility of excessive culture; we engender in them, by the latter, debility, disease, and death; and in our turn we become their prey. All this indeed is but a cycle of events, that requires no learned mind to fathom, and to comprehend; it is a matter of every day occurrence, and, though perhaps not entirely unheeded, is not dwelt upon in the fulness of its bearings and importance.
Let us now consider the diseases of plants, as a study progressive to those of man; and as their physiology has so extensively served us, we may possibly also find in their pathology much material for instruction; not that it will be attempted to shew that the same diseases affect both kingdoms, but that diseases, though dissimilar in effects, may have similar sources.
Unfortunately, there are not many men in this country, who need go further than their own gardens to find abundance of disease among their fruit trees and vegetables. The vine, the apple and the potato, common to most gardens, will furnish specimens.
It is an error of a serious kind to suppose, that the parasites which infest plants are not essentially the cause, or, perhaps, more properly speaking, the elements of disease. I confine myself here to disease of parasitic origin, as that is the subject of which I am chiefly treating.
That parasitic growths are the elements of disease in some instances, is now beyond dispute. The experiments of Mr. Hassall, detailed in Part II. of the Transactions of the Microscopical Society of London, are most conclusive; and they are of that simple nature, that any one may convince himself of their accuracy, by a repetition of them from the directions there laid down.
He says, the decay is communicable at will "to any fruits of the apple and peach kind, no matterhow strong their vital energies may be, by the simple act of inoculation of the sound fruit with a portion of decayed matter, containing filaments of the fungi. We may use with success the sporules of such fungi; but in this case the decomposition does not set in so quickly; in the one case, the smaller filaments of the fungi have advanced several stages in their growth; while in the other, the sporules have yet to pass through the several stages of their development."
Mr. Hassan, however, seems to speak doubtfully as to the mode in which the disease becomes naturally introduced;[60]how the spores enter the fruit, "is not very clear—though probably, it is by insinuating themselves between the cells of which the cuticle is composed, or perhaps by means of the stomata, where they are present. I may here state that the experiments were made on fruit, while living, and attached to the tree."
But why should there be a doubt as to the parts by which the sporules of minute fungi enter the plant, when it is clear, that not only can they enterby the spongioles, but by the stomata of the leaves, and mingle with the sap. It is true, that they make their appearance and grow upon the leaves and the fruit; but these are the situations most adapted for their fructification. I have seen the spores of the fungi which attack the cucumber and vegetable-marrow, in the cells of the hairs, and even their filamentous prolongations; these appropriate the fluids conveyed to the cells of the hair, rupture them, and at length fructify.
On referring to Dr. Lindley's Medical and Economic Botany, I find that many fungi are the active elements of disease, and in a manner which renders it highly improbable that they are so in any other way, than by obtaining an entrance to the sap of the plants. Of the microscopic fungus which destroys wheat, the Uredo caries of De Candolle, we find the habitat to be within the ovary of the corn, and that 4,000,000 may be contained in a grain of wheat,—now this and another fungus, the Lanosa nivalis, are said to destroy whole crops of corn: we cannot imagine that such an extensive affection, can have any other source than by means of the spores through the sap, seeing that bruising of the surface, or rupture of the cuticle of the apple, a comparatively soft fruit is necessary to produce the disease artificially in them; besides, a grain of corn containing vibriones, when grown and having fruited, the new fruit also contains them—now here, as this is I believe almost invariably thecase, either they or their ova must be carried with the sap to the new germs.
It is rather a remarkable fact, that these entophytes appropriate the nutriment destined for the plant in which they grow, they are consequently the means in many instances of its entire destruction, though only partially so in others.
There are many Fungi which have this tendency. The Puccinia gramienis, "preys upon the juices of plants, and prevents the grain from swelling." The Æcidium urticæ, common on nettles, deprives the plant on which it grows, of the organizable matter, intended for its own nutrition. The Erysiphe communis, overruns and destroys peas. The Botrytis infestans, "attacks the leaves and stems of potatoes." The Oidium abortifaciens, attacks the ovaries of grasses—and the Oidium Tuckeri, "a formidable parasite, destroys the functions of the skin, of the parts it attacks." The latter has been most injurious to the vines, during the last two years. I have known instances in which the vines have been cut down, and every means taken to rid the houses of the disease; but this year, it has made its appearance, with all its former virulence, in the new shoots.
This, however, is sufficient to shew that plants are liable to disease, depending upon parasitic growths, which affect their vital powers, and deprive them of their natural nutritive fluids.
But somewhat similar diseases belong also towarm climates; in a letter from Cuba, dated Dec. 1843,—Mr. Bastian writes, "a plaguehas appeared among the orange trees—a mildew attacking the leaves and the blossoms, which finally dry up. It most frequently kills the trees. None of the orange family are exempt; lemons, limes, and their varieties, with the shaddock and forbidden fruit, have all suffered." This disease has continued without intermission, till the present year,—when the same gentleman writes, Feb. 20th, 1850: "The evil exists, although in a diminished degree, so much so, as to have allowed the trees to produce me 30,000 oranges again. In old times, the same plantations produced me 100,000."
The West India sugar-canes are also liable to a disease, which the Rev. Mr. Griffiths, in his Natural History of the Island of Barbadoes, speaks of, in the following manner: "This, among diseases peculiar to canes, as among those which happen to men, too justly claims the horrible precedence." This disease is called the Yellow Blast. It is difficult to distinguish the Blast in its infancy, from the effect of dry weather.
There are often seen on such sickly canes, many small protuberant knobs, of a soft downy substance. It is likewise observable, that such blades will be full of brownish decaying spots. The disease is very destructive to the canes. It is observed, that the Blast usually appears successively in the same fields, and often in the very same spot of land.
This Blast is often found far from "infected places," and the infection always spreads faster to the leeward, or with the wind.
"It is remarkable if caneshave been once infected with the Blast, although they afterwards to all appearance, seem to recover; yet the juice of such canes will neither afford so much sugar, nor so good of its kind, as if obtained from canes which were never infected."
I may here allude to the circumstance, that in the island of Cuba, the destructive mildew is commonly called,la pesta.
It were needless to multiply instances of other endemic and epidemic diseases of vegetables; they are well known by practical observers to be very numerous, and I believe, in most instances, depending upon fungoid growths. The destruction of vegetables by insects, is of a very different nature to that produced by the fungi; it would be as unreasonable to consider the consumption of corn and herbage by locusts, as a disease of vegetation, as the massacre and devouring of human beings by cannibals, a disease of the human body.
It is true that insects are exceedingly destructive to plants, but as far as I am able to obtain information, they appear to be so chiefly by their voracious propensities; they consume the structure of the plant in its entity, and do not primarily interfere with its vitality. The instance of the vibriones, before-mentioned, seems at first to be an exceptionto the rule, but this is rather apparent, than real; and it may be made to apply more as a confirmation, than an obstacle to the vegetable theory: for if we may fairly compare the diseases of animals with those of plants, the existence of entozoa in the latter, would be considered an essential point to be substantiated.
Having now considered the question as to the infeasibility of supposing that chemical fermentation is the basis upon which a theory of diseases can be sustained, and having shewn that life is inseparable from infection, and miasmatic generation;—having explained the phenomena of the dispersion of diseases by comparison with the dispersion of plants, and finally, having demonstrated that the physiology and pathology of plants bear so close a relation to each other, and that their epidemic affections depend upon minute organic germs, I submit to the judgment of my readers, whether there is not much reasonableness in the application of the facts to the inference—that living germs are the cause of epidemic disease in man and animals.
RESULTS IN PROOF OF THE TENABLENESS OF THE PROPOSITION.
————
SECTION I.
OBSERVATIONS ON SOME OF THE LAWS OF EPIDEMIC DISEASES.
The results obtained by comparing certain facts connected with Epidemic Affections of animals, with analogous affections in plants, afford, from the few instances I shall here notice, a very strong presumption, that analogous causes operate in the production of these affections. I have already quoted from Hecker, to shew that previously to, and during the Epidemics of the Middle Ages, the minuter forms of animal and vegetable life appeared to be called into existence, much more abundantly than usual; that famines prevailed in consequence of failure of cereal crops, no doubt depending then, as now, upon the various forms of fungiferous growth. I cannot refrain quoting here, a passage or two from our old friend Virgil; for he confirms not only the fact of peculiar showers inconnexion with diseases, but he also refers to the rust of corn, thus:
150. "Mox et frumentis labor additus; ut mala culmosEsset rubigo ...... Intereunt segetes."Georg. 1.
150. "Mox et frumentis labor additus; ut mala culmosEsset rubigo ...... Intereunt segetes."
150. "Mox et frumentis labor additus; ut mala culmos
Esset rubigo ...
... Intereunt segetes."
Georg. 1.
Georg. 1.
Then:
311. "Quid tempestates autumni et sidera dicam?. . . . . .322. "Sæpe etiam[61]immensum cœlo venit agmen aquarumEt fœdam glomerant tempestatem imbribus atrisCollectæ ex alto nubes."Georg. 1.
311. "Quid tempestates autumni et sidera dicam?
311. "Quid tempestates autumni et sidera dicam?
. . . . . .
. . . . . .
322. "Sæpe etiam[61]immensum cœlo venit agmen aquarumEt fœdam glomerant tempestatem imbribus atrisCollectæ ex alto nubes."
322. "Sæpe etiam[61]immensum cœlo venit agmen aquarum
Et fœdam glomerant tempestatem imbribus atris
Collectæ ex alto nubes."
Georg. 1.
Georg. 1.
The occurrence of black showers in this country has been observed during the present year, and I understand that in the fenny countries of the East, the corn has suffered much from the Uredo. I am not mentioning the circumstances as cause and effect, but merely to call attention to the fact, that unusual phenomena of this kind have been generally associated with disease of the animal and vegetable tribes.
The same causes also predispose plants as well as animals, to epidemic attacks of disease. The repeated observations in the public journals on the subject of ventilation, drainage, and over-crowding, render all notice from me needless, to shew that these, though they do not produce the diseasestreated of, yet that under the influence of bad air, bad drainage, and over-crowding, epidemics are fostered and spread.
Lastly, says the Count Philippo Ré, "I would remark that ifbad cultivation, and especially bad drainage, does not produce bunt or smut, it is certain that those fields, the worst treated in these respects, suffer the most from these diseases."
It has been remarked by many observers, that a greater fecundity has attended upon Pestilences, and this has been proved by comparison, that the births in proportion have far exceeded the ordinary limit.[62]In juxtaposition with this observation, I will place the following, not as a proof, but as a remark made quite independently of the subject of which I am treating. "From the first the diseased ears are larger than the healthy ones, and are sooner matured. What appears singular, but which I have not, perhaps, sufficiently verified, isthat the seeds are more abundant than in a sound ear."
Now these are facts which require amplification, and if these two alone should be shewn upon an extensive field of observation, to apply not only to corn, but to other members of the vegetable kingdom, as I doubt not will be the case, though I am not fully prepared to prove it, it would be difficult to dissociate the fertility of the two living kingdoms from the operations of one and the same, or an analogous law.
The epidemic diseases of plants are both infectious and contagious, at times they are observed to be endemic only, and then depending particularly upon some local causes. This is a law of diseases which applies equally to those of men and animals. In connexion with this law is another, which, as far as I am aware, has not hitherto been noticed in connexion with plants. The potato disease, which excited so much interest and created so much anxiety for the poorer classes of society, led the Government of this country to employ the most learned men to investigate the subject, in the hope of propounding some reasons which should explain the cause of the calamity, and thereby deduce a method of eradicating the evil, or, in other words, discover a cure for the disease. Many were the opinions as to the cause of the distemper, which it were useless here to recount, but a method was suggested, to which most people, I believe, looked forward with great anticipations, and this was to obtain native seed, and to sow it on virgin soil. Was the end accomplished? No.For though the seed was sown, and the plants grew, the disease still appeared among the newly imported individuals, to as great an extent, as among the native or domesticated plants.
As a parallel to this, it may be stated, that, as regards either endemic or epidemic disease, those persons newly arrived, either in a district or country where these prevail, are even more liable to them than the residents.[63]Again, I have learned, that where the potato disease has been so bad as to render the crop almost valueless, the best plan to be adopted is, to allow the plants to remain in the earth, and thus leave such as retain their germinating powers to come up spontaneously the following year. I certainly saw one large field treated in this way, yield a crop almost without disease.
The seasoning, in this instance, seems to bear a comparison with the seasoning of animals and man, under a variety of diseases, which for a time renders them insusceptible of another attack. It therefore does not appear so improbable, that these affections may be regarded, as Unger, the German botanist supposed, the Exanthemata, or Eruptive Fevers of vegetables.
Another feature seems to associate the Epidemics of plants and animals, in a manner suggestive of analogous causes operating in both instances.
The lungs of animals and the leaves of vegetables, are their respiratory organs, by means of which, the blood in the one case and the sap in the other, derive gas from the air, and impart gas to it, each taking what is thrown off by the other.
Now the epidemics among vegetables, have a remarkable tendency to exhibit their effects primarily on the leaves, and particularly on those parts which are appropriated to the function of respiration. It is from the stomates that many of the fungi commence to germinate, and their fructification may be seen sprouting from the opening composed of a chink, surrounded by a peculiar arrangement of cells, which constitute the breathing apparatus of their victim.
In the earlier epidemics, of which we read, one of the most remarkable circumstances, was the extraordinary influence the poisonous matter appeared toexercise over the lungs,[64]and they again, were the means of propagating the disease, and spreading the contagious particles through the atmosphere, for we read: "Thus did the plague rage in Avignon for six or eight weeks, and the pestilential breath of the sick, who expectorated blood, caused a terrible contagion far and near, for even the vicinity of those who had fallen ill of plague was certain death; so that parents abandoned their infected children, and all the ties of kindred were dissolved."[65]"The like was seen in Egypt. Here also inflammation of the lungs was predominant." "Here too thebreathof the sick spread a deadly contagion."
It is more than probable that all infectious matter obtains an entrance to the system through the lungs. Inspiring the air containing the pestilential semina is, indeed, the only plausible explanation of infection; for though the skin is indubitably an absorbingsurface, and capable of taking up and conveying to the blood any noxious matter applied to it, yet it is far more probable that the lungs would effect this process with greater rapidity. Then the stomach, the only other absorbing surface to which extraneous matter can be applied, is not likely to be the part where the elements of disease would obtain an entrance to the system, for many facts prove, that infectious matter may be swallowed without any injurious consequences, unless in a very concentrated state. Instances are not easily found of diseased matter having been swallowed, except where diseased vegetables have formed under some combination of circumstances, a portion of diet.[66]
Many facts are on record which prove the powerful effect of diseased grain when made into bread, and taken for any length time as a principal article of food. The history of Ergot of Rye is too fresh in the memory of most people to require more than an allusion here. The stomach had no power over the secale, its poisonous properties were retained, after having been submitted to the digestive process, as was evidenced by the abortions and gangrenes it occasioned.
But diseased wheat is also capable of inducinggangrene, and it is more than probable, that many diseases might be traced to the use of infected grain of various kinds. An interesting account of a family who lived at Wattisham, near Stowmarket, in Suffolk, and all of whom suffered more or less from living on bread made of smutty wheat, may be found in the Philosophical Transactions. The mother of this family and five of the children, consisting of three girls and two boys, all suffered from gangrene of the extremities; the father lost the nails from his hands, and had ulceration of two of his fingers.[67]Dr. Woollaston wrote thus in a letter on this case: "The corn with which they made their bread was certainly very bad: it was wheat that had been cut in a rainy season, and had lain on the ground till many of the grains were black and totally decayed, but many other poor families in the same village made use of the same corn without receiving any injury from it. One man lost the use of his arm for some time, and still imagines himself that he was afflicted with the same disorder as Downing's family." It is not unlikely this was the case, for numbness and loss of power was one of the well marked characters of the disease.
What other afflictions may be due to diseased vegetation and adulterated articles of food, and what loss of life may accrue from cheap and adulterateddrugs and chemicals is hardly yet dreamt of.[68]The systematic practice of adulteration of almost every article of diet which comes to table has become a serious question for the legislature to consider. Take only the article of milk, upon which the young children of large towns and cities, make their chief meals, with the addition of bread. How much milk comes into London from the country, how much is obtained from stall and grain-fed cows in the metropolis, and how much is said to be consumed, would be an interesting calculation. It is pretty well known that a mixture is sold by which a retailer of milk may increase his supply by one-third or one-half. It was discovered in Paris that the brains of animals, when prepared in a particular manner, formed, when mixed with a certain proportion of milk and water, a very fine and deceptive cream; in that city this system was carried on to a considerable extent. I could not help alluding to these facts while speaking of diseased grain, for who shall say to what extent a miller in a large way of business, may be able to "work in," as it is called, a considerable amount of smutty corn in the manufacture of flour? Now, as diseased grain is knownto induce abortion, it is impossible to tell how small a portion may in some cases produce the effect; we may therefore say with Thomas of Malmesbury, "There is no action of man in this life which is not the beginning of so long a chain of consequences, as that no human providence is high enough to give us a prospect to the end."[69]
To return,—associated with these observations are other facts of considerable weight. Before and during pestilences, abortions are more frequent than in ordinary times; infectious and contagious diseases induce abortion; besides this, and independently of disease, conditions of the atmosphere have been known to exist when abortion has been an epidemic affection; of this Dr. Copland says, "to certain states of the atmosphere only can be attributed those frequent abortions sometimes observed which have even assumed an epidemic form, and of which Hippocrates, Fischer, Tessier, Desormeaux, and others have made mention." With this reference I will close the subject of comparison between the affections of the breathing apparatus in animals and plants, merely alluding to the probability that under some conditions of atmosphere, independently of heat, &c. vegetables without any other assignable cause will become abortive.
SECTION II.
WHAT IS THE NATURE OF THOSE POISONS WHICH MOST RESEMBLE THE MORBID POISONS IN THEIR EFFECTS ON THE BODY?
In the early part of this book, I considered the nature of poisons generally, and had occasion to remark upon the characters which separated poisons into two distinct classes. 1st, Those which have the power of self multiplication; and 2nd, Those destitute of this property.
Of the first we have seen that the poisons of epidemic diseases multiply both in and out of the body.
The poisons of infectious diseases, not usually epidemic, do the same. Those of endemic affections, such as ague and some fevers, usually become multiplied out of the body only, but under some circumstances, and peculiar atmospheric conditions, they may be also multiplied within the body. The amount of these poisons necessary to produce their specific effects, may be inappreciable. Of the second class, there are two kinds, those derived from the organic kingdom and those derived from the inorganic kingdom. Of these, the amount necessary to produce their specific effects is appreciable and pretty well known.
But among those poisons, consisting of organicproducts, there is one which seems to hold an intermediate place. This is derived from one of the Fungals, and as it takes this remarkable position as a link of connexion between the two classes of poisons, I may be excused quoting a passage of some length upon this agent, from Dr. Lindley's Vegetable Kingdom. "One of the most poisonous of our fungi, is the Amanita muscaria, so called from its power of killing flies, when steeped in milk. Even this is eaten in Kamchatka, with no other than intoxicating effects, according to the following account by Langsdorf, as translated by Greville. This variety of Amanita muscaria, is used by the inhabitants of the north-eastern parts of Asia in the same manner as wine, brandy, arrack, opium, &c. is by other nations."—"The most singular effect of the amanita is the influence it possesses over the urine. It is said, that from time immemorial, the inhabitants have known that the fungus imparts an intoxicating quality to that secretion, whichcontinues for a considerable time after taking it. For instance, a man moderately intoxicated to-day, will by the next morning have slept himself sober, but (as is the custom) by taking a teacup of his urine, he will bemore powerfully intoxicatedthan he was the preceding day. It is, therefore, not uncommon for confirmed drunkards to preserve their urine, as a precious liquor against a scarcity of the fungus. The intoxicating property of the urineis capable ofbeing propagated; for every one who partakes of it has his urine similarly affected. Thus with a very few amanitæ, a party of drunkards may keep up their debauch for a week."
This property of the amanita, at once places it in a separate category from all other organic poisons, it has yet to be shewn upon what this intoxicating fungus depends for its activity. Whether some secretion is formed in the tissue of the plant, or whether some new arrangement of the particles of matter or modification of the sporules, is brought about by entering the system, it is impossible to say. Langsdorf states that the small deep-coloured specimens of amanita, and thickly covered with warts, are said to be more powerful than those of a larger size and paler colour. As the effect is not produced until from one to two hours after swallowing the bolus, and as a pleasant intoxication may be obtained by this agent for a whole day, and from one dose only, there is a defined line between this and the ordinary narcotics and stimulants in common use. That the digestive powers of the stomach have no influence over the intoxicating properties of the plant, is manifested in the fact, that the active principle passes into the urine, not only not deteriorated but apparently increased, for, as we have seen, a teacup of the urine from a man, intoxicated by taking the amanita into his stomach, will cause him to be more powerfully intoxicated than by theoriginal dose. We have, therefore, but two conjectures left for consideration, either the original intoxicating principle is excreted from the system in a condensed form, in which case its indestructibility by digestion, makes it approach the ordinary organic poisons, or there must be an increase of the toxic agent, in which case we must suppose a reproductive process having taken place in the system. "There is," says Dr. Mitchell, "in the wild regions of our western country, a disease called themilk sickness, thetrembles, thetires, theslows, thestiff-joints, thepuking fever,&c." The animals affected with this disease, "stray irregularly, apparently without motive;" they lose their power of attention, and finally tremble, stagger, and die. "When other animals—men, dogs, cats, poultry, crows, buzzards, and hogs, drink the milk or eat the flesh of a diseased cow, they suffer in a somewhat similar manner." This disease is attributed by Dr. Mitchell to the animals having grazed on pasture contaminated with mildew, and the resemblance to the effects of the amanita, together with the persistence of the specific principle within the fluids and tissues of the body, render it more than probable that to some fungoid growth, is due the peculiar toxic effects here noticed. Further: "The animals made sick by the beef of the first one, have been in their turn the cause of a like affection in others; so that three or four have thus fallen victims successively." De Graaf states, that buttermade from the milk of diseased cows, though heated until it caught fire, did not lose its deleterious properties. The urine of diseased animals, collected and reduced by evaporation, produced the characteristic symptoms. All these facts point to some peculiarity in the properties of matter not yet investigated or at least not explained. If we may assume that reproduction is here an element of the persistence and apparent multiplication of active matter, I know only of one instance to compare with it. A gentleman about to deliver a lecture on the properties of arsenic, and its history generally, made two solutions of a given quantity of arsenious acid, in the following manner. He took a certain amount of distilled water, and the same of filtered Thames water, and made his solutions of arsenic by separate boilings, he then as soon as possible placed the liquids in identical bottles, carefully prepared for their reception. In the one which contained the arsenic boiled in river water, the hygrocrocis is now growing, while that boiled in distilled water remains perfectly limpid and free from any vegetable production. There can scarcely be a doubt, that the filtration of river water was not sufficiently purifying to remove the minute spores of some lower forms of vegetation, which not only live in arsenic but have resisted the temperature employed in boiling an arsenical solution to saturation.
As to the first class, or truly reproductive andmorbid poisons, the most heterogenous ideas have from all time existed. I have introduced the notice of the above poisons, viz. the Amanita, and that which engenders the milk sickness, to compare the results of the morbid poisons on the human body with them, and also to associate them with the effects of diseased grain. From the Amanita and that other fungoid matter which is said to produce the milk sickness, there appears to be a purely toxic action on the system, but in the instance of diseased grain, a blood disease, ending in gangrene, or a specific and peculiar action of the generative organs is the consequence, and where the latter occurs, the poison usually expends itself on these parts, either by inducing abortion, or augmenting the catamenial secretion.
Now, the morbid poisons, if studied only in their results, shew that there is a combination of these two actions. There is usually, in the first place, a toxic or poisonous action, and secondly, a deteriorating or decomposing action on the blood, by which there is a tendency to low or asthenic inflammation and gangrene. It matters not what form of fever we take as an illustration, whether intermittent, pestilential, or exanthematous, either will serve the purpose of shewing how completely the effects of vegetable organic poisons resemble those which for the sake of distinction (I suppose) have been denominated Morbid Poisons.
Take an attack from the paludal poison. It isusually ushered in with head-ache, weariness, pains in the limbs, and thirst, with other symptoms; all these are indicative of a poisonous agent in the blood: then come the full phenomena of the disease at a longer or shorter interval, and tending ultimately to destroy some organ of the body. The mind suffers during the course of the attack, and delirium occasionally happens. In severe cases of this disease, which were more frequent formerly than now, coma, delirium, and frenzy were observed at the commencement of the attack, and a tendency to rapid disorganization of one or several of the viscera.
If we take the effects of poison of Erysipelas, of Scarlet Fever, or Plague, in each we find at the onset more or less general derangement of the system, usually with cerebral disturbance and disordered action of all the dynamic forces of the body, which clearly indicate the action of a poison; then, unless some favourable symptoms arise, the blood exhibits a steady advance towards disorganization, and sphacelation of one or more tissues or parts of the body ensues. In Erysipelas the force of the diseased action is expended on the skin, and subcutaneous cellular tissue; in Scarlet Fever the fauces ulcerate, and slough and the parotids suppurate; in the Plague there is a general tendency to putrefaction, and the formation of glandular abscesses with sphacelas. Without going any further into this matter, for my present intention is merely to drawnotice to certain facts, let me now ask, whether or not, do the poisons of the Ergot, the Uredo, and the Amanita, exhibit more analogy in their action on the nervous system, the blood and the tissues, than any other poisonous agents with which we are acquainted? If the whole range of the lower fungi could be examined in reference to their operation on the blood, as decomposers of organic compounds,—if experiments could be made, by which the properties of fungoid matter could be detected, I would venture to say the whole of the phenomena of these diseases could be readily comprehended and their intricacies unravelled.
We know that the fungi are poisonous, that at times and seasons, and under variations of climate, they vary in their effects, and perhaps lose altogether these properties. We know that the fungi produce gangrene of the tissues, and disorganization of the blood; we know that their spores pervade the atmosphere, and are ready, under favouring conditions, to increase and multiply; we know that they are ubiquitous, and that those conditions most favourable to their development, are exactly such as are proved to foster and engender disease, and above all, they have been proved to be the elements of some diseases in man, in animals, and in plants. Can as much be said of any other known agents, animate or inanimate, comprised in our category?
It has been said, we do not see after death,—theinterlacing mycilium, or the sprouting pileus; therefore the fungi are not the agents of disease—it has been said that carbonic acid and alcohol are not found as products of diseased action—consequently disease is not a fermentative process. "In all cases," says Liebig, "where the strictest investigation has failed to demonstrate the presence of organic beings in the contagion of a miasm, or contagious disease, the hypothesis that such beings have cooperated, or do cooperate in the morbid process, must be rejected as totally void of foundation and support." Much as I admire the genius of this great man, it is difficult to refrain from remarking, that I doubt if any of his great discoveries would have been made, if, in the first instance, hypotheses had not formed the basis of all his researches. It has been said, "that casual conjunctions in chemistry, gave us most of our valuable discoveries:" and it is from casual conjunctions that hypotheses are usually formed, the working out proves either their fallacy or their truth, but to say that an hypothesis has no foundation, until demonstrated to be true, is rather knocking down argument. And who, let me ask, has been more prolific of hypotheses than our continental neighbour? Yet he, according to his mode of reasoning, would sweep away all such words from the vocabularies of philosophers. What foundation has the chemical hypothesis of disease, when it fails to explain the most important elementof contagious and infectious diseases: viz. the reproductive property of their germs?
It is perhaps necessary to say something in explanation of the sudden deaths arising from morbid poisons. They may occur from two causes. One being the result of a concentrated amount of poison germs being inhaled into the lungs, and acting as an ordinary toxic agent; and the other, which I put only hypothetically, the consequence of the rapid evolution of gas in the vessels arising from a sudden decomposition of blood, as it passes through the lungs. The only authority I have for this supposition, is the fact that the blood after death, from pestilential affections, is found to be far advanced towards decomposition; that in Paris last year, two patients were bled while suffering from Cholera, and with the small quantity of blood which flowed, bubbles of air also escaped:[70]and besides this, it was demonstrated by Mr. Herapath, that ammonia was given off from Cholera patients, both by the lungs and skin. These facts, though they are not conclusive, nevertheless render it probable that such an explanation is not entirely out of reason—especially too, when we know how fatal are the effects of uncombined air, when it enters the vessels near to the heart.
SECTION III.
WHAT RESULTS DO WE OBTAIN FROM THE EFFECTS OF REMEDIAL AGENTS, IN PROOF OF THE HYPOTHESIS?
I have here used the word hypothesis, because, having so far advanced in the enquiry, I trust sufficient has been said to render the term applicable.
Under the term remedial agents, I shall include all those causes, whether natural or artificial, which tend to neutralize or destroy the germs of infection, or miasmatic poison, whether this be effected out of or within the body.
First, then, let us consider the results of drainage and cultivation in removing the causes of endemic disease. One well authenticated case is as good as a thousand. I will take one, which, from its source, will be received as unexceptionable; and from its association with a very learned and amusing book, will be accepted as an agreeable reminder of the many pleasant hours spent in the perusal of the poet Southey's "Doctor."
"Doncaster is built upon a peninsula, or ridge of land, about a mile across, having a gentle slope from east to west, and bounded on the west by the river; this ridge is composed of three strata; to wit, of the alluvial soil deposited by the river in formerages, and of limestone on the north and west; and of sandstone to the south and east. To the south of this neck of land, lies a tract called Potteric Carr, which is much below the level of the river, and was a morass, or range of fens when our Doctor first took up his abode in Doncaster. This tract extends about four miles in length, and nearly three in breadth, and the security which it afforded against an attack on that side, while the river protected the peninsula by its semicircular bend on the other, was evidently one reason why the Romans fixed upon the site of Doncaster for a station. In Brockett's Glossary of North Country words, Carr is interpreted to mean 'flat marshy land,' 'a pool or lake;' but the etymology of the word is yet to be discovered.
"These fens were drained and enclosed pursuant to an Act of Parliament, which was obtained for that purpose in the year 1766. Three principal drains were then cut, fourteen feet wide, and about four miles long, into which the water was conducted from every part of the Carr southward, to the little river Torne, at Rossington Bridge, whence it flows into the Trent. Before these drainings, the ground was liable to frequent inundations; and about the centre there was a decoy for wild ducks; there is still a deep water there of considerable extent, in which very large pike and eels are found. The soil, which was so boggy at first that horses were lost in attempting to drink at the drains, has been broughtinto good cultivation, (as all such ground may be) to the great improvement of the district; for till this improvement was effected,intermittent fevers and sore throats were prevalent there, and they have ceased from the time the land was drained. The most unhealthy season now, is the spring, when cold winds, from the north and north-east, usually prevail during some six weeks; at other times Doncaster is considered to be a healthy place. It has been observed that when endemic(?) diseases arrive there, they uniformly come from the south; and that the state of the weather may be foretold from a knowledge of what it has been at a given time in London, making an allowance of about three days, for the chance of winds. Here, as in all places which lie upon a great and frequented road, the transmission of disease has been greatly facilitated by the increase of travelling."
I feel certain of being excused for transcribing this long passage from Southey. It would have been impossible to convey its whole meaning without giving it entire. The continuation of the chapter is no less instructive and applicable to our subject, though more particularly so to an extension of the enquiry. The sore throats and intermittents, from which Doncaster has been freed, by the drainage of Potteric Carr, informs us at once that decomposing matter is the material by which the poison of fever is vivified and sustained, the wet and boggy state of the soil is just the condition, when no drainage exists, to bring into activity the germs ofdisease, which otherwise would lie latent. So satisfied and acquainted are we with the elements necessary for the production of fever, that we might as certainly bring about an endemic intermittent by forming an artificial bog, as we could be sure of growing mushrooms by making a bed in the manner laid down by gardeners for this purpose. Dr. Lindley also says, "thePolyporus fomentariushas been artificially produced in Germany, but merely by placing wood in a favourable situation, and keeping it well moistened. Five or six crops were obtained in the year."
Let warmth, moisture, darkness, and decaying matter be given, and inanimate disintegrated particles will soon be converted into definite forms and combinations instinct with life. It is by the unseen forms of living beings, that the atmosphere is preserved from becoming charged with deadly gases; they take the first rank in the great scheme of animated beings, the plant first, and then the animal. "Let the earth bring forth grass." "Let there be lights in the firmament." "Let the waters bring forth the moving creature, and fowl that may fly," and "Let the earth bring forth the cattle, the creeping thing, and the beast." This is the order of creation, of living things, and the earth was prepared by vegetation for the animal world. The work of conversion is accomplished by vegetation; and this is consumed for the construction of higher organizations.
The laws which govern and control the universe,are as definite and as wonderful among invisible atoms, as those which regulate the enormous masses floating in space; and the time will come when the advancing intellect of man will measure and weigh the morbid poisons, as he measures and weighs the stars. Why should the laws of Epidemics be less understood, than the laws which govern the course of comets? The aspirations of man have led him to penetrate the heavens, which charm and inspire him; he studies rather the more violent disturbing elements of nature, the thunder-cloud and the fire of heaven, than the silent pestilence which steals over the earth. I cannot conceive it possible that the Intellects, which are occupied in procuring means for the Majesty of this empire to issue her mandates with the velocity of a spirit to the nethermost parts of the earth, should be incapable of solving so deeply interesting a mystery as the causes and nature of pestilential diseases. It would seem that man prefers to issue a mandate of destruction many thousand miles distant, than to disarm the pestilence at his door. It is barely a century since Galvani observed the twitchings in the muscles of a frog's leg, and the battery, still named after him, has already become an agent of instantaneous communication between places many miles distant. But how many centuries have passed away, each one succeeding the other, with its millions of victims to epidemics? And where are the remedies for the evils? Drainage and cleanliness, with all their advantages, were better understood and more fully carried out by the ancientRomans than by ourselves; there are monuments, though crumbling to decay, to tell us of the vast enterprise of these people and of the value they set upon a healthy and vigorous constitution, and how well they understood the means of warding of disease.
Cultivation and drainage are now fully understood to be the basis by which a healthy condition of air is to be obtained, next to that, cleanliness and ventilation; if either be neglected a sickly, mouldy, and unwholesome contamination of atmosphere ensues; the odour of a bog is proverbially mouldy, and so is that of an ill-ventilated house or cellar; dryness, or the fresh pleasant scent of clean water, are the antagonists of these; the aromatic odours of vegetation are opponents of putrefaction, and consequently of the development of the lower forms of life. All empyreumatic matters prevent mouldiness and decomposition; and odours arrest and prevent the growth of mouldiness. The oil of birch, with which the Russia leather is impregnated, and which gives it so pleasant an odour, effectually prevents mouldiness, and consequently decay.
Lindley says, "It is a most remarkable circumstance, and one whichdeserves particular enquiry, that the growth of theminute fungi, which constitute what is called mouldiness, iseffectually preventedby any kind of perfume."[71]Cedar hasbeen used, from time immemorial, for a like purpose; and I doubt not the recommendation of Virgil, before quoted, in reference to the burning of cedar, was founded on some practical utility of this kind, though itsmodus operandiwas unknown to him. Allied to these is a curious circumstance, and worthy attention. I copy the following from an old work on Pestilences. "It is remarkable that when the Plague raged in London, Bucklersbury, which stood in the very heart of the city, was free from that distemper; the reason given for it is, that it was chiefly inhabited by druggists and apothecaries, the scent of whose drugs kept away the infection, which were so unnatural to the pestilential insects, that they were killed or driven away by the strong smell of some sorts of them." "The smell ofrue, and the smoke of tobacco, were prescribed as remedies against the infection; but especially tar and pitch barrels, which it was imagined preserved Limehouse, and some of the dock-yards from infection."[72]
Pitch and tar dealers are everywhere spoken of as being remarkably exempt from infectious diseases.
Cold infusion of tar was used in our colonies as a prophylactic against the Small Pox. BishopBerkeley was induced to try it when this disease raged in his neighbourhood. The trial fully answered expectation—for all those who took tar-water, either escaped the disease, or had it very slightly.
Tan yards and places in the immediate vicinity, are said to be free from pestilences. The tanners of Bermondsey are said to have escaped the Plague of London, and one person only died in Gutter Lane, where was a tan yard. The tanners of Rome are also stated to have been free from Plague. Dr. M‘Lean refers to the exemption of tanners at Cairo.Tannin is prejudicial to most vegetables,—but Dr. Lindley says it is not always so to fungi. "A species of Rhizomorpha is often developed in tan pits." I should imagine that neither plants nor insects would be found very abundantly, where tannin prevails; yet we find that the gall-nut is formed for the protection of an insect from injury by weather, and as a temporary means of sustenance.
The custom of fumigating with odoriferous substances, does not therefore appear upon this view of the matter to be destitute of importance; indeed, the universal practice stamps it at once, as an efficacious remedy for the purposes of disinfection. The introduction of chlorine fumigation, seems to have superseded, in a great measure, the use of fragrant herbs and woods; and it is questionable whether the substitution be altogether desirable oradvantageous. Many scents may be agreeably and usefully employed, with much less chance of annoyance to the patient, and considerably less injury to articles of furniture, &c.
The fumigations of sulphurous acid and chlorine are, perhaps, more adapted as disinfectants in uninhabited apartments;—their power to destroy vegetation, is well known. They have been used, chiefly, with the idea of neutralizing gaseous exhalations, particularly chlorine, as it tends to combine with hydrogen, to form hydrochloric acid, and then to unite with ammoniacal matters, forming hydrochlorate of ammonia. This, supposing noxious or pestilential effluvia consisted of the ammoniacal exudations variously combined, was an exceedingly efficacious method of rendering them inert; but as we feel convinced that no ammoniacal compound could possibly be the cause of infection, we must look to the influence these gases possess over other forms of matter, and as they are so destructive, even in minute quantities, to vegetable existence, it is possible that their beneficial effects may be due to this property. The immediate neighbourhood of gas works is prejudicial to vegetation, I imagine, from the amount of sulphurous vapours, and to this has been attributed the exemption of persons employed in these works. Many other instances might be cited of a similar nature.
I have now to speak of medicinal agents, and here comes a considerable difficulty.
If we might believe all that has been written on the sure and certain remedies for the "ills that man is heir to," we should be led to acknowledge that both nature and art were prodigal in antidotes and specifics. The all-bountiful hand of nature, I do not doubt, has at the same time scattered the seeds of good and of evil. The fertilizing showers fall to irrigate the soil, and produce food and nourishment to man; here and there is the reeking morass "feeding unnatural vegetation," and if man takes up his abode in its vicinity, the rains which made it unhealthy, have also made it highly fertile; by labour and cultivation he may convert the mephitic bog into a waving corn-field, and the seeds of life and sustenance be made to supplant the seeds of death and corruption.
It is generally believed, that where there are particular and specific diseases, there also may be found appropriate and specific remedies; the discoveries of chemistry, it is not improbable, may in some respects have retarded the progress of natural medicine. In the early ages of the world, the "healing plant" must have formed the staple of medical commerce, for though Tubal Cain[73]has been considered as the first surgical instrument maker, because he was the first artificer in brass and iron, we have not discovered that chemical compounds entered into the composition of physic, till verymany years after his time. To the alchemists we owe the science of chemistry, and much of the physic of the present day may be traced to them. The multiplicity of ingredients which at one time entered into the composition of one dose of physic could only be spoken of under the title of "legion." Who shall specify the active and curative ingredient (if there be one), when from five to a hundred may have been exhibited at the same time? It has been the pride of our physicians, that the pharmacopœia has been simplified; it has not reached its most simple form yet. That many simple plants have specific and wonderful power over disease, is an indubitable fact, but I firmly believe that the laudable, though mistaken efforts of physicians to improve their effect by various combinations, have been the means of throwing many valuable medicines into oblivion; I must also add, that cheap physic and adulterations have had no small share too in the banishment of much valuable physic from ordinary practice. It has been believed, and I think with much reason, that a thorough search into the qualities of plants, would shew that "they are capable of affording not only great relief, but also effectual and specific remedies." "That they are not already found, is rather an argument that we have not been sufficiently inquisitive, than that there are no such plants endued with these virtues."