CHAPTER III

Ripple Marks in Sand(After Lyell).

In human skin, and in the anthropoid apes, those scroll-like patterns present almost infinite varieties of detail, and they often resemble a condensed railway plan, showing junctions, blind sidings, loops, triangles, and curves. There is one important distinction to beobserved. The lineations of skin ridges are not always quite uniform in breadth, but broaden out sometimes or dwindle away. Again, they are dotted with sweat-pores and do not always, when printed from, show those pores in the same degree of patency or openness. Hence a little variation is inevitable when the same finger is several times impressed under varying conditions. It is not to be forgotten that, to a limited extent, this is true of a rigid box-wood engraving or steel plate, or lithographic stone, which give somewhat divergent results with varying degrees of pressure in printing, moisture of atmosphere or paper, and other conditions.

In this country the feet do not afford a favourable field of study to the dactylographer. So far as identification is concerned, little use could be made of them practically. In the East, however, it is different, and many years’ residence there gave me opportunities to observe that the toes, unrestrained by the use of stiff leather boots, are mobile and powerful, grasping as fingers do. The carpenter in Japan, for example, uses his toes to grip and steady the board he is sawing or hewing, while many of my readers must be familiar with the extraordinary agility of Japanese acrobats in the use of their feet and toes. In those cases the ridges are often varied in grouping, and well defined in development. A European baby generally begins life with similar simian-like powers. But so far as my own observations go, the patterns in the hands usually show a somewhat higher degree of evolution, a more complex and intricate network of lines, than those exhibited by the feet of the same person. Hence, apart from the greater convenience of inspecting them, the finger-printshave greater value for the purpose of identification. Cases, however, of crime, might readily occur even in this country, where the imprints of naked feet might yield important and irrefutable evidence of one’s presence at a scene of evil-doing.

But there are other important points of scientific interest besides their evidential value for identification. An important problem in evolutionary development, on which a considerable amount of literature begins to accumulate, is the serial relation of the limbs. Professor Bowditch, the distinguished biologist, of Harvard University, U.S., wrote me, of date November 18th, 1880,thus:—

“Dear Sir,—I have just read inNatureof October 28th, your article on the skin-furrows of the hand. The subject interested me because it so happened that fourteen years ago, at the suggestion of the late Professor Jeffries Wyman, I made some prints of the finger and toe tips with the hope of throwing some light on the question of the antero-posterior symmetry of the body. Since reading your article I have made some new impressions from the same individual, and it is interesting to notice the unchanged character of the cutaneous furrows.”

Some additional particulars are added in the letter, and a fine finger imprint was enclosed.

It is well to remember that the comparison of the ridges to those of a ploughed field does not always, and in every way, hold good. As I have elsewhere said:[C]

“The lines are not of uniform width. Ofttimes they may be likened rather to the mountains and valleys in a good survey. The ridges sometimes split or send little spurs down into the neighbouring valleys; at other times a ridge seems to cleave, giving rise to a formlike a tarn or lake in a limestone range: here and there solitary islands rise in the valleys, and sometimes quite an archipelago takes the place of some of the commoner patterns. Indeed, the ordinary nomenclature of an ordinary physical geography map may be found quite helpful in laying a case clearly before a magistrate or a jury. And just as we find in the case of mountains and valleys in a map, every variety of shape may occur in a finger-pattern.”

Here it may be as well to state, as we shall see more precisely further on, that an English jury is well enabled to judge of the conformity of two patterns, one of which is suspect only, and the other officially printed from the fingers of some one in custody—by great photographic enlargement of the exhibits in the case, used as evidence.

The ridges, as may be seen by an enlarged photograph (as on frontispiece), do not always continue to be of quite uniform width throughout. Sometimes they taper away sharply like a railway point, or trickle off in diminishing dots; or again, especially where something like triangles occur, called deltas (after the Greek letter, Δdelta), they flatten out in breadth considerably. In old age they are found usually to have partaken of the general drying up and shrivelling of the tissues.

In the cold or shivering stage of ague and fevers, and in the affection called Reynaud’s disease, in which the fingers may tend to become pale and bloodless, some slight shrinking of the ridges also takes place, a point which might be of importance in the measurement of enlarged exhibits in the trial, for example, of an old Indian soldier or traveller who had been subject to fits of ague.

I have heard Sir A. Moseley Channel, who hasinformed himself well about finger-print matters, in a charge to a jury in a murder case, refer to the doubtful and unsatisfactory nature of evidence from a print done by a sweaty finger.

The fact that sweaty finger-marks have been adduced in evidence of crime makes it important for lawyers, police officials, judges and jurymen, to understand what is meant by such natural records. A mark from pure sweat would necessarily be excessively transient, as it consists chiefly of water and salines, and should properly contain no greasy matter whatever. Dr. Reginald Alcock, of the North Stafford Infirmary, in a recent paper read at Stoke-on-Trent, and since republished inThe British Medical Journal, described his researches into the relation of the sweat-pores to practical surgery, and to the recognized difficulty in sterilising the skin for subsequent operation. Dr. Alcock shows that there may often be found remaining, after the best efforts to cleanse the surface, a stubborn residue of live and obnoxious matter in those tiny invisible ducts, matter which had insidiously gained entrance from without. Now such decaying or dead particles of foreign protoplasm would, I think, readily enough account for the very faint traces of oily matter sometimes observed, which oiliness makes sweat from a skin, fair and clean in the ordinary sense, leave slight but somewhat persistent traces on such substances as glass and the like.

In a case reported some time ago, inThe Birmingham Post, Detective-Sergeant Charles Munro, on cross-examination as to a sweaty smudge left on glass, said: “The impressions on the window-pane were sweat-marks. They had conducted experiments in ScotlandYard, and ascertained that sweat-marks lasted on glass for a week if not exposed to the wind.” Here, I suppose, the distinction between a sweat-mark proper and a somewhat greasy sweat-mark was not discerned. Even a deliberately designed greasy mark is volatile to a certain extent just as the oil of new paint dries in a day or two according to the weather.

In theGuide(p. 65) I have alluded to the fact of coloured sweat orChromidrosis,thus:—

“A blackish ooze takes place in some hysterical cases. More striking is the class of cases in which the colouring matter is derived, like the bright colours in the plumage of parrots, from copper, and in some cases from iron. Workers in copper have been found subject to it. The sweat is generally of a bluish colour in those cases. Red sweat has been observed in lockjaw. A kind of saffron colour I have found to be not very uncommon in some classes of malarious cases. One lady I attended had an extraordinary temperature during some of the attacks, the thermometer recording 110° Fahrenheit. With a temperature of about 104° Fahr. she did not seem to be really unwell. I took good impressions at one of those times, with the yellow-coloured sweat. Ordinarily, however, sweat does not help, but hinder, impressions from being made. A case of blue sweat came under my treatment quite recently. There was no history of copper poisoning.”

Since writing the above, I have met with other cases of coloured sweat. My teacher, the late Sir Thomas McCall Anderson, in his work,Contributions to Clinical Medicine, mentions some very interesting facts in this connection in the chapter on “Hemidrosis.”

Herbert Spencer, in the May number of theNineteenth Century(1886), discussing the Factors of Organic Evolution, explains the origin of the ridges in a passage which I must quote infull:—

“Continuous pressure on any portion of the surface causes absorption, while intermittent pressure causes growth: the one impeding circulation and the passage of plasma from the capillaries into the tissues, and the other aiding both. There are yet further mechanically produced effects. That the general character of the ribbed skin on the under-surfaces of the feet and inside of the hands, is directly due to friction and intermitten pressure, we have the proofs: first, that the tracks most exposed to rough usage are the most ribbed; second, that the insides of hands subject to unusual amounts of rough usage, as those of sailors, are strongly ribbed all over; and third, that in hands which are very little used, the parts commonly ribbed become quite smooth.”

Before reading this chapter, let the reader carefully examine the clear lineations shown so well in the photographic picture of the Zebra’s stripes, opposite. They will be found to resemble very closely the lineations on the skin of human fingers, as printed when enlarged by photography, forming very similar patterns. Similar linings occur in the hide of the tiger.

Grevy’s Zebra.—Showing Lineations like Finger-Print Patterns.

[Photo. Pictorial Agency]

Where two lines, beginning as parallels, curve to divide, a fresh line begins to appear between. Sometimes a single line forks into two or three. Again, triangular arrangements of lineations are seen on the zebra, and one can trace some of these back into lines running as a parallel series. Surely the causes which produce the ridges on a human or anthropoid finger cannot be quite the same biologically as lead to the formation of similar patterns in the skin of the zebra. There are mechanical or physical conditions, however, which condition the formation of ridges in a sandy shore, of powdery snow blown by the wind and tossed on a smooth frozen lake, as has already been noticed, and these conditions are being carefully elucidated by scientific observers. But why living tissues should produce patterns like those, just in those positions, and then reproduce them in living descendants with slight but important variations, is a totally different question, the answer to which must be reached in a different way.

While the ridges and furrows lie in parallels or curve in the same direction over some considerable surface of the sole and palm, they also gather up into more or less intricate, scroll-like patterns at various points besides those of the last joints of the fingers, which have chiefly engrossed popular attention hitherto. In man, the lemurs, lemuroids, and apes, these pattern points are numerous. In my own hands, there are on the left hand, besides the five finger-tip patterns, other five like them, and the right hand contains six. There are thus twenty-onecomplexpatterns which might be used for identification.

On the other hand, when one reads of a mathematical attempt to compute the probabilities of two finger-prints being alike, it is not a question simply of comparing an unknown finger smudge with collections containing ten finger-prints each, for the unknown smudge may have been made, not from one of a possible set of ten finger-tip prints, but from one of those other local patterns not on the finger-tips at all. There is a saying often attributed to Huxley, who certainly used it wisely, that the value of grist from the mathematical mill depends on the quality of the corn put into the hopper. But official amateur mathematicians have made many much worse mistakes than the above in regard to probabilities in the realm of finger-print evidence.

In a few cases, especially in the feet patterns, often a very plain character, parallel or slightly wavy lines of no precise design, so to speak, may be found. A short time ago, when applying mustard to the feet of a lady in some kind of fit, I observed this almost featurelesspattern in her toes. If such cases were as common in the hands as they are rare, the finger-print method would hardly be of any avail for identification. A teleologist of the old school of Paley might argue with some plausibility that the possible usefulness of those intricate patterns was the true meaning of their existence, otherwise not yet explainable. That the old Paleyan conception of nature having an end or purpose in view, the teleological explanation of things as useful to the being possessing them, had its own usefulness in giving a broader view of natural history facts in their interrelations, is borne out even by so great an authority as Charles Darwin himself. Are the markings in a bird’s eggs recognized by the sitting bird in those cases where the markings are peculiar—and some are like written characters—or are they purely accidental and useless? A correspondent inThe Country-Sidewrote a short time ago, describing a test case he observed of a thrush in his possession. This bird built a nest and laid therein five eggs, “varying in size from a good-sized pea to the normal size. The smaller ones I took away and substituted one from a wild bird’s nest; this the following day I found laid at the bottom of the aviary smashed. I again repeated the addition with the same result. I had carefully marked the eggs, so that there could be no mistake.” The writer signed himself “W. A., Wimbledon.”

Dr. Wallace’s view, as I understand it, is that variations in wild animals were due chiefly to immunity from enemies, allowing free play to the natural tendency to variation, kept only in check by its dangers, such as leading to betrayal by conspicuous colouring, and so on.Professor Poulton inThe Colours of Animals, 2nd ed. p. 212,says:—

“It is very probable that the great variation in the colours and markings of birds’ eggs, which are laid close together in immense numbers, may possess this significance, enabling each bird to know its own eggs. I owe this suggestive interpretation to my friend, Mr. Francis Gotch: it is greatly to be hoped that experimental confirmation may be forthcoming. The suggestion could be easily tested by altering the position of the eggs and modifying their appearance by painting. Mr. Gotch’s hypothesis was formed after seeing a large number of eggs of the guillemot in their natural surroundings.”

Australian ewes know the bleat of their own lambs, however immense the flock, and all through nature we find this useful note of recognition. One of the most philosophic interpreters of living phenomena, viewing things from a very recent standpoint—Professor J. Arthur Thomson, in his fascinatingBiology of the Seasons(p. 174), writing of the colour and texture of birds’ eggs,says:—

“In some cases, it is said, the shell registers hybridism—a very remarkable fact. It is another illustration of the great, though still vague, truth that the living creature is a unity through and through, specific even in the structure of the egg-shell within which it is developed. For although the shell is secreted by the walls of the oviduct, it seems to be in some measure controlled by the life of the giant-cell—the ovum—within.”

Such pattern-forming qualities are found in many fields of nature, very beautifully, for example, as we have seen, in the skin of the zebra; on the back of a mackerel; in the grain of various kinds of wood; in the veining of leaves and petals; and in the covering or substanceof seeds such as the nutmeg and scarlet runner bean. Sir Charles Lyell, in hisElements of Geology, figures the ribbing of sand on the sea-shore in a wood-cut which might be an enlarged diagram of human skin. (See fig. on page32). In hisPrinciples of Geology(5th ed., vol. i., p. 323) there is, again, a figure described as a section of “spheroidal concretionary Travertine,” which contains many linings strikingly like those with which we have to deal in this little work.

a. section of pine-wood stem.

b. a human thumb-print.

It follows from these analogies that a method of analysing and classifying such patterns might have very wide utilities beyond its relation to finger-prints. It is easy, for example, to recognize the same zebra in quite different pictures. Another point of practical importance is this, that a smudgy or blotchy impression, supposed to be that of a criminal present at some seat of crime, might be the impressed copy merely of some object or texture other than human skin, but containing lineations of similar arrangement. An outworn transversely cut branch of a tree might readily produce a print like that of a human finger. An expert would probably notice that in the lineations there were no real junctions, each woody ring remaining apart from the others; but, again, there are some human fingers of such patterns. I think the bloody smear officially reproduced as impressed on a post-card in facsimile,and purporting to have come from “Jack the Ripper,” at the time of the Whitechapel horrors in the eighties, may have been produced by the sleeve of a twilled coat smeared with blood. It contained no characters specially characteristic of skin lineations, which it was presumed to be an example of, as impressed.

Apart from all that, lemurs, lemuroids, apes, anthropoids, and monkeys, all show on hands and feet, skin lineations in patterns similar to those of man. In the anthropoid apes it would not be easy to discriminate them from those of human beings. Some of these were figured in myGuide, and Dr. Otto Schlaginhaufen has supplied numerous good prints.

If Edgar A. Poe, in his famous mystery of evil deeds done by a gigantic ape, had been acquainted with finger-print methods, he might have pictured the police as still more mystified by the imprints of seemingly human hands.

There are two methods of observing systematically the lineation patterns.

1.—The Direct Mode.—This might be done simply by many people by looking at the lineations with the unaided vision. Till quite recently the author found no difficulty in doing this, with myopic eyes that could see something of the texture of a house-fly’s eyes in a good light. My earliest observations of the finger-patterns were made in this way, while the patterns were reproduced in pencilled outlines. The condition of the actual ridges and furrows themselves, with their open and acting or closed and dormant sweat-pores, ought to be familiar to the student of dactylography, who is apt to narrow his vision by the contemplation only of deadimpressions made in ink or otherwise. A lens such as botanists use for field work is very useful, and a high power is neither necessary nor very helpful. Drawings of the patterns ought to be made from time to time with coloured or “lead” pencils, and those drawings should be accurately adjusted by the use of rubber and compasses.

2.—The Indirect Method.—This is done by the medium of casts and printed impressions. Casts may be made of clay, putty, sealing-wax, beeswax, gutta-percha, hard paraffin, varnish, half-dry paint, and the like. Printed impressions or dactylographs may be obtained from greasy or sweaty fingers, blood, printer’s ink, or various substitutes for it.

Within this method, again, two very distinct and complementary kinds of results may be obtained, which I have elsewhere described as Positive and Negative. The first or Positive is that, for example, which is used officially for the record of convicted prisoners by printing with ordinary printer’s ink, just as a veined leaf or fern, or a box-wood engraving is printed from. Here the ridges or raised lines appear black on a white ground, while the intervening furrows appear white, as do also the minute pores dotted along the crest of each ridge. (Seefrontispiece.)

In the other method, as when the fingers are impressed on a carefully smoked surface of glass, the projecting ridges lift up the carbon of the soot, leaving a white pattern behind, with the sweat-pores forming black punctuations, while the receding furrows leave the black surface untouched. When such impressions have to be used again, as for evidence, they shouldbe carefully varnished, as they are exceedingly liable to be destroyed by the slightest contact.

In a case under judicial investigation where an official imprint had to be compared with one done by accident negatively on smoked glass or the like, the black lineations would not closely correspond—would, in fact, considerably diverge in pattern. This might tend to confuse judge and jury if the distinction of negative and positive dactylograph were not made clear by the expert witness. Then the apparent divergences could easily be demonstrated to be very significant coincidences.

Five years of my early life were spent in learning a trade in Glasgow—that of the soon-to-be-obsolete Paisley shawl manufacture. It seemed to me to have been an utter waste of time, but part of my duty was to deal with the arrangement, classifying, and numbering immense varieties of patterns, printed with every conceivable variation of combined colours. It was impossible to carry these on memory, and one had to resort to mnemonic means of classification.

Now, the immense significance of the variety in human finger-patterns dawned upon me very early, when I had once begun to interest myself in them.

Design-like Patterns in Finger-Prints No. 1.(Diagrammatic)

Design-like Patterns No. 2.

There are many patterns, which, when analysed into their composing elements, present analogies to artistic designs, a view which is no mere personal fad, but has been affirmed with enthusiasm by many artists in designs to whom I have pointed out those figures. Here are a few, by way of illustrating this point (space will not permit of more). Those figures are from real human finger-prints rendered diagrammatically. This is the first step, then, to catch with the eye the pattern ordesign; give it a class name, and you have at once established some practical basis of classification in finger-prints. Then it is possible to frame some kind of catalogue for reference arranged like a dictionary with its sub-alphabetic order, in an almost infinite series. The initial difficulty is generally that which arises from want of skill in printing, which technical points will be considered subsequently. A soft and flexible substance like the ridges in human fingers does not always yield an exactly similar impression in two successive moments,under varying conditions of temperature, fatigue, and the like. Nor does the analogy of mathematical diagrams always fitly apply in such a case. Even in steel engravings and fine etchings, as the connoisseur well knows, the degree of intensity of the pressure and other conditions will modify to some slight extent the resulting imprint, but what I wish to emphasize is, that if the original pattern had any value at all resulting from its complexity as a pattern, the variation in printing as now done officially by experienced police officials will not impair much its value as evidence of personal identity in a court of law. Even the amateur will soon, after a little practice with good materials, attain a very fair amount of clearness and uniformity in his imprints.

In this chapter I propose to bring together a few important points of a biological character, which are so vital that even in so curtailed a discussion they cannot be ignored. We shall also glance—it must literally be the merest glance—at the problem of man’s genetic descent, in so far as it begins now to be illumined, however faintly, by a comparative study of finger-prints. Comparatively little of a final character has as yet been achieved, but there are now not a few active and intelligent observers in many lands, and the scientific results often attained under the greatest difficulties are so far greatly encouraging. Fortunately the day has long passed away when it can be considered irreverent to enquire modestly as to who were one’s ancestors. In a very true biological sense every human individual is known to have run through a scale of existence, beginning from the lowest mono-cellular organism, through something like a tadpole or salamander, into a vertebrate and mammal type, not easily to be discriminated from the undeveloped young of rat, or pig, or monkey. Now, if he is not in any way individually degraded by this actually demonstrable course of development, why should he be thought racially degraded by an honest scientific effort to trace the origin of his species from lowly animal ancestry? The process may be slower,but is no less determined by divinely established law. Our grandfathers believed that the Creator breathed into the organized and shapely form of Adam (= “a man”) a portion of the divine spirit, by which he became a living soul, and forthwith took his dignified place in nature. To me the old story, when retold in more modern and exact phrase, leads us to an entirely hopeful and inspiring conception of the origin and evolutionary destiny of our race.

When we approach the threshold of man’s first appearance on the globe, we have reached a geologic epoch when our sober earth seems to have sown most of its wild oats. Its “crust” is pretty stable, and at least in its broad distribution of sea and land, it does not seem to differ very greatly from what its appearance presents on a modern physiographical map. Minor differences there must have been, as even our modern English coast-line shows, and there may have been other conditions than now exist to account for many of man’s early migrations, but those differences are still matters of discussion. There were, possibly, enough certain bridge-like links between lands now apart and separated by wide stretches of sea, but, as a rule, such conclusions have been deductively reached, and are not definitely established on scientific evidence.

After rising above one-celled to more complicated organisms, we reach a class of creatures in which a radiate or wheel-like form obtains, that is, radial symmetry, as in jelly-fish, star-fish, urchins, and sea-anemones.

Fishes occupy, perhaps, about the lowest level among the back-boned or vertebrate animals, and we mayreadily notice that some of their fins occur in symmetrically arranged pairs, while others, again, occur singly. Now with this arrangement of such appendages in pairs symmetrically arranged there begins the appearance of something definitely like what we mean by limbs. Some present-day fishes use some of their fins as legs to clamber and crawl on rocks or ashore. I remember seeing, in a Japanese tea-house by the solitary sea-shore, not far from where the great arsenal of Yokoska now hums busily, a very beautiful gurnard, blue as to its outspread wings like the sapphire gurnard. Those fins were painted like the wings of a butterfly, and it crawled about in the limited sea-water, on rocks, under cliffs, and among sea-weed, with butterfly-like legs or processes from the roots of those wing-like fins. With such a special adaptation of their fins, fishes began to conquer the land. Seals and whales, as is well known, are mammals which have been driven back again to the sea.

Thesing, in his suggestiveLectures on Biology(English translation, p. 13),says:—

“All extremities of the higher vertebrates, however widely they may differ in construction, may be traced back biogenetically to the so-called Ichthyopterygium, as we see it in the lower shark-like fishes. Unequal growth of the single skeleton parts and a considerable reduction in their numbers transformed the Ichthyopterygium into the five-fingered extremity characteristic of all vertebrates from the amphibians upwards.”

Anthropoid Lineations.a, from hand of orang, left index;b, from foot of chimpanzee, left index;c, from foot of orang, left index.

Anthropoid Lineations.

a, from hand of orang, left index;b, from foot of chimpanzee, left index;c, from foot of orang, left index.

Of course the great end of an animal is at first to fill its own belly, and in order to do this, if fixed as some molluscs are, it must contrive to bring nutriment within its reach, and if mobile limbs come to be developed toachieve locomotion, by fin in water, limb on land, and wing in air. After the vertebrate and mammal stage was achieved, the five-fingered limb takes various forms, as the paddle of the whale or wing of the bat. There are three great periods in geological development of animals—the Primary, which is, roughly speaking, the typical period of fishes; the Secondary, when reptiles prevail; and the Tertiary, the great age of mammals. Many geologists recognize a fourth period, the Post-Tertiary, Quaternary, or Diluvian, when existing species have been established. It is not till this latest period has arrived that we can detect unmistakable evidences of man. There are, however, many reasons which lead to the conclusion that his racial roots go still further back in time. Did he arise as a “mutation,” one of those rare sudden changes observed to take place even at the present time, by which a species suddenly departs from its ancestral type and is transformed? Let us briefly look at the main facts of mammalian ascent. The great herbivorous reptiles—some do not seem to have beenstrictly herbivorous—do not seem to lead us far on our path. Widely spread throughout the world, the Theriomorphs or beast-shaped reptiles seem to approach the mammal type, but they were too helpless and unwieldy, and had little brain-power wherewith to direct their energies. The earliest genuine mammals were small, not only relatively to those great creatures, but really little, rat-like rodents. Then we find arboreal creatures, driven to the trees for refuge and for food, squirrel-like animals, agile to escape from their monstrous but clumsy and stupid foes on the ground, and using their paws nimbly as hands to grasp and tear, or to break nuts and other food.

Lemur-like animals (lemuroids) then come on the stage, and among them—among the earliest of them—we begin to detect traces, on feet and hands, of those patterned ridges, the beginnings of which we have been seeking. Hand and brain and voice are the trinity of social construction. The spider and the mantis (or praying insect) have nimble, hand-like organs—very striking and conspicuous in the mantis; the chameleon among reptiles, the parrot among birds, the squirrel among lower mammals, all have somewhat hand-like organs used in hand-like ways; but when we reach the higher mammals, the sense of touch is finely intertwined with the power of varied and discriminative grasping, pressing, or rubbing. The elephant, which appears at first in the strata as about the size of a dog, grows in size and brain power as the ages roll along. But his path seems now to be closing. With his sagacious brain, and prehensile, sensitive trunk, he can do wonders, but, like the horse, he is likely to be passed by; the greattool-maker finding it easy now to make bearers swifter or more powerful than they are.

It is in man and the anthropoid apes that we first find the correspondence between hand and brain that promises mastery. The ugly, painted mandrill, even, has beautiful lady-like hands and takes care of them like a lady. All the higher apes show complicated finger-patterns like those of man.

The rugæ in apes and men seem clearly to have served a most useful purpose in aiding the firm grasp of hands or feet, a very vital point in creatures living an arboreal life, as they and their racial predecessors are now presumed to have done. In that case, however, would not one pattern, a simple one, have done as well as any other? Here, then, the great balancing principles of variation and heredity come into operation. The variety of patterns is immense, and for aught we know new ones may be being evolved at the present time. Here again, heredity comes in, for there is certainly some tendency to repeat in a quite general way the pattern of sire in the hands and feet of son. I have as yet found no quite close correspondence of detail in any case brought under my own notice. The question of identifying a person on one or two lineations involves so many practical problems of obscurity in printing and the like, that it is more appropriate for discussion in another chapter.

In a work published last year onScience and the Criminal, by Mr. C. Ainsworth Mitchell, after quoting a reference I made on one occasion to the influence of heredity insometimesdominating finger-patterns, the author goes on to say: “While there is questionably ageneral tendency for a particular type of finger-prints to be inherited just as any other bodily peculiarities are liable to be passed on from the parents to the children, there is by no means that definite relationship that Dr. Faulds hoped to establish.” The full passage in my paper inNaturereferred to, wasthis:—

“The dominancy of heredity through these infinite varieties is sometimes very striking. I have found unique patterns in a parent repeated with marvellous accuracy in his child. Negative results, however, might prove nothing in regard to parentage, a caution which it is important to make.”

The truth is, I have very frequently emphasized the fact that in such similar patterns in sire and son there is no real danger of false identification where several fingers are compared in their proper serial order. It is not even likely that two such fingers would agree exactly in lineations, number, curvature, etc., if carefully measured in the way set forth in this work.

A more remarkable criticism is to be found in p. 63, thus: “The existence of racial peculiarities in finger-prints, which Dr. Faulds believed that he had discovered in the case of the Japanese, has not been borne out by the experience of others.” The author then mentions some observations on this point by Galton, who thought that “the width of the ridges appeared to be more uniform and their direction more parallel in the finger-prints of negroes than in those of other races.” The word “negroes” here is delightfully vague in an ethnological discussion. I have written nothing to justify the above remark. My belief has long been that there isnoracial difference of yellow, white, red, or black, to use the good old Egyptian classification, but that the human familyis one, and that view (right or wrong) was enunciated often by me in Japan, both by speech and pen. Mr. Mitchell’s strange misconception must surely be based on my words in the article by me quoted above, where, after enumerating some elements in patterns from different races, I go on distinctly to say: “These instances are not intended to stand for typical patterns of the two peoples, but simply as illustrations of the kind of facts to be observed.”

I had pleasure in giving my subscription and support to the recent First Universal Races Congress, which has done much, I believe, to consolidate scientific opinion as to the essential unity of our kind, a belief not so old or universal as many think, dating, indeed, not much more than a century back, if so far, as a scientific opinion, not biassed by the slave interest.

Of much more importance now is the relation to human beings to the great anthropoid stocks.

It is usual to separate the lemurs, which have strong affinities to monkeys and to men, from the anthropoids, or man-like apes, forming two great orders of

Lemuroidea, andAnthropoidea.

In 1909, however, a paper was published by the Zoological Society of London, in which this separation is considered to be no longer justifiable, so that the lemurs and big man-like apes (orang, chimpanzee, and gorilla) would no longer be held as separate orders or sub-orders. There were some who hoped to show that the races of men corresponded to three primitive anthropoid stocks, linked to the three kinds of anthropoid apes. Whether the new view be correct or not, and there is somethingto be said in its favour, there can be no reasonable doubt now as to the close affinity which those creatures have to ourselves and to one another.

When we first encounter remains of man or his close predecessor in the records of the rocks, he was a dweller in holes and caves of the earth. He certainly did not make pots of any kind, or at least he has left no such remains. Probably he had no such companions even as the domestic dog or cat, no cattle, not at first any kind of grain crop. He lived on roots and fruits, hunted, and fished. Those early people have often been called Troglodytes, from the Greek τρώγλη, a cave.

Professor Keith, the learned curator of the museum of the Royal College of Surgeons, has advanced the theory that about the middle of the Miocene Age a group of creatures existed, having affinities to man as he now is, which group the professor names Proto-troglodytes. From these sprung three classes of Troglodytes, namely:

The Gorilla;The Chimpanzee;Man.

Some eighty-seven anatomical features are said to be possessed by the gorilla in common with man only, while the chimpanzee has ninety-eight such features as belong to man. The gorilla has the best and biggest teeth, and in this respect progressive deterioration went on through the orang-utan and the chimpanzee to man. According to the estimate of Professor Keith, there are not in the whole world, at present, more than 100,000 chimpanzee, and some 10,000 gorillas.

The subject of twins is likely in future to be very interesting in relation to the resemblance of their finger-patterns. The distinction is now made of twins proceeding from one zygote or fertilized ovum, and twins proceeding each from different fertilized ova. In the first case, it is supposed that the twins are necessarily of the same sex, while in the other, each twin child may be of the sex determined by the fertilized ovum from which it sprung. Clearly, in the latter case it might often happen that both twins might be male, or both female.

Dr. Berry Hart quotes from the records of another observer (Wilder) in which there was a pair of “identical” twins, in whom the similarity was complete even to the finger-prints. [Brit. Med. Jour., July 29th, 1911, p. 215.] I have found in the same family male and female withresemblingfinger-prints, but none which could be called identical, but opportunities of comparing twins of the same sex do not often occur. While writing this chapter I examined twins of the same sex (female). Their finger-prints are very similar, but details diverge in many directions. The matter merits close attention. But how are we to determine that twins of the same sex are from one ovum, seeing that there might be a coincidence of twins of the same sex proceeding from separate ova? If their finger-prints are “identical,” is that the main evidence? or do identity of features, colour of hair, voice, manners, and character, come up independently? If one questions the theory, the “identity” must be very complete indeed, to give it vraisemblance, for how often do we not find that children of the same parents, not twins, but born with many years intervening, show most striking resemblance? The alleged complete identity of finger-patterns, however,is a most interesting and novel point, and ought to receive close attention from parents and physicians. A curious fact about hereditary resemblance is this, which I have frequently observed. A child resembles, say, a mother as a rule, but at some emotional, angry, or vexed moment, lines are marked in the face by muscular movements which bring out like a mask a striking likeness, say, of the father, or of some other progenitor. Besides this, a child at different stages may resemble in succession different near relatives, and in a very striking degree resemble them. But with regard to finger-patterns there is no such variability. Even a month or two before a child is born its little heraldic crest begins to be firmly fixed for each finger, as it is to be throughout life.

The disease called Acromegaly, or giant growth, involves great expansion of the ridges and furrows, but no case of actual change of patterns has been observed as yet. The attention of medical men should be given to this affection in regard to modification of linear arrangement.

The likeness or divergence of finger-patterns in neighbouring supernumerary fingers and toes might yield interesting results if carefully recorded. Extra fingers are commoner than extra toes. The webbing of fingers, as in the chimpanzee, might also be noticed, and any association with retrograde patterns, in the fingers concerned.

The rapid growth of a literature of Criminology is partly the result of better methods of identification. It is unscientific to reason about the personal peculiarities of all the Toms, Dicks, and Harrys, when Tom may beDick, or Dick Harry under a different alias. The criminologist can now use his prison statistics as to age, habits, and the like, with much greater confidence and precision. In an interesting, but somewhat reckless work on “Criminal Man,” which summarizes the teaching of the eminent Italian authority on the anatomy and psychology of the criminal—of the Italian criminal at least—Cesare Lombroso, we are told (p. 20): “Long fingers are common to swindlers, thieves, sexual offenders, and pickpockets. The lines on the palmar surfaces of the finger-tips are often of a simple nature, as in the anthropoids.” But they are not, necessarily, of a simple nature in the anthropoids, but often highly ornate and complex in their ramifications. In the lower monkeys they are much simpler, and Sir F. Galton thought it was so sometimes in the negro peoples. Indeed, one is not surprised to meet such simple lineation patterns now and again in cultivated people, without any criminal taint, or negro blood, or any anti-socialistic tendencies that can be easily detected. A cautious prison doctor in Glasgow, Dr. Devon, has written a clever book which gives much food for sober reflection. He seems to say that the criminal is not a kind of species by himself: “If those who come to prison for the first time were made the subject of examination, it would be found that they are principally remarkable for the absence of what the books call criminal characteristics.” (p. 11.)

There are important points connected, with the printing of finger-patterns, especially for legal investigation, which come now to be considered. A human finger, as we have seen, is not, for printing purposes, just like a lithographic stone, a box-wood engraving, or a plate of zinc, steel, or copper. In ordinary printing, especially of high-class and delicate engravings, the quality and fluency of ink, the smoothness of surface and hygrometric conditions of paper—due sometimes to local atmosphere, and sometimes to climate generally—the skill of workmen, all the conditions co-operate in producing variations, slight it may be, but noticeable in the results obtained. In the case of finger-prints we might also have to consider the willingness or unwillingness of the subject having his finger-prints officially taken. A finger—even that of a dead person—is compressible, while retaining on the whole the pattern of its furrows and ridges, and hence under fairly similar conditions, the printed products may be somewhat different in appearance. The same fact would apply, no doubt, also to impressions taken from an indiarubber stamp, made, we shall suppose, for stamping purposes in regard to documents, in imitation of a particular finger-print pattern. Greater compression tends to flatten out the ridges and to narrow the intervening grooves, while it may also tend, especially whenassociated with over-inking, to obliterate some of the characteristic ramifications of the pattern. But, again, the finger of a living person is usually in a state of physiological activity. It swells or shrinks, drying up or exuding moisture from its many pores, which facts, however minute and insignificant they may appear to the uninstructed, to the trained dactylographer they leave a most interesting and significant record behind.

Examine carefully a ridge which has been printed—and, if possible, photographically enlarged—at various periods not long apart, and the pores with which it is dotted will be found, while retaining their relative positions, to vary somewhat in their degree of patency. A single ridge might be compared to a naval cruiser, the numerous funnels of which are not all belching forth smoke at the same time, but one is almost smokeless while its neighbour is quite active. Those pores which have been copiously emitting sweat are seen, when imprinted, to be larger than those that were inactive. An imaginary case was once suggested to me as a final blow to finger-print identification. A certain Mr. William Sykes is officially known to be recruiting his valuable health at one of His Majesty’s sanatoriums for people of his profession. That celebrated artist’s “thumb”-print, however, has been found liberally spotted all over the scene of some tragic area of crime. What is to be said? Well, the prodigality of display of the well-known sign-manual, in circumstances when gloves are almost invariably now worn by experts, might well arouse suspicion in itself, but it would easily be found in such a case that the pattern had been prodigally repeated with too great fidelity in the matter of sweat-pores,which, in the case of an active burglar, who is a sober, hard-working fellow in spite of his faults, would vary with each successive imprint, in a way that no manufacturer of bogus “thumb”-prints could easily follow.

The fact that a finger—a clean finger—is naturally, to some slight extent, greasy, partly from sebaceous secretion, enables the expert dactylographer by various chemical and mechanical means to obtain a pretty clear vision, even in minute detail, of what before had been quite invisible. A mere accidental smudge from a slightly oily palm or finger, if imprinted on glass, japanned tin, varnished or polished wood, etc., may have its invisible lineations brought out by dusting gently upon it some light powder of appropriate colour. Dr. René Forgeot, in 1891, first called attention to this method of bringing out latent imprints, and my friend, Dr. Garson, of this country, gave it further developments.

In myGuideI have mentioned some of my own results with modifications of these methods.

On a pane of glass which a malign finger is suspected to have touched, a fine black powder gives vivid and beautiful results, the sooty matter clinging to and revealing the oily surface of the lineations in very full detail. In my article inNatureof 1880 a sooty imprint is shown to have helped an innocent man to establish his innocence, but in this case the imprint was quite direct. The powder should be gently blown over, or dusted lightly on to the greasy impression, with a soft camel hair brush which is perfectly clean and dry. Care should be taken not to breathe on the glass, or a damp, smeary effect may result. I have not foundsable brushes act so well as those made of camel hair, a fact which their structure under the microscope helps to explain. (Seefrontispiece.)

The best treatment of a greasy smudge on a dark ground, say the surface of a japanned cash-box, marble slab, school slate, or enamelled door panel, is carefully to dust over the object with a fine white powder, such as the ordinary tooth-powder of the chemists, or still better, as I find, with the light carbonate of magnesia. In one sense this may be said to yield anegativeprint, but an important qualification arises. The patterns now in white are the ridges which before were black, while the furrows remain dark as at first. In a smoked glass print the white ridges have not imparted something to the glass, but have simply removed the carbonaceous deposit previously there. Practically, however, the whitened ridges have the quality of a negative imprint, as previously described.[D]

Greasy finger-marks may also be acted on chemically, so as to bring out details by the application of osmic acid. If there is any olein or oleic acid in the mark, as there generally is in human finger-marks, the acid deepens the tone of the almost invisible lines into a brownish hue, revealing all their richness of detail. I have succeeded in etching finger-marks of this kind on glass by means of hydro-fluoric acid. They remain quite indelible in all their details so long as the glass itself endures. The patterns thus etched can be very well brought into view by painting a dark background on the reverse, or pasting dark paper behind. There is a clear layer of the skin in both palms and soles, thefat of which is eleidin. That particular kind of fat does not stain with osmic acid in the usual way. The sweat of palms and soles is not supposed to contain any fat at all, but there would seem to be some faint trace of it in sweat. The greasy surface of the skin as a rule comes from the sebaceous glands, as previously described. When clean palms leave a greasy smear, as they often do, I think the greasiness must generally come by transmission from other parts of the body, or from contact with foreign greasy substances, which are common enough.

For those who wish to study dactylography, the apparatus is neither complicated nor expensive. A good pair of compasses, a botanical lens, a school slate or tin plate or porcelain tile, a small pot of fine printer’s ink, and an ink-roller or photographer’s “squeegee” will suffice for most purposes. For the expert who must make fine measurements of enlarged photographs, and perhaps defend them under keen forensic criticism, one or two instruments are required, presently to be described.

The ink may be daubed evenly and thinly on the slate, tile or plate, but it is better to use a small printer’s roller for the purpose. Avoid all fluff, hairs, or grit, which thoroughly spoil any print. The roller should always be scrupulously cleaned before laying aside, and it is well to provide a tin case for its reception. The remaining stock of ink should be carefully levelled a-top, and covered with a drop or two of linseed or other oil, which will preserve it in good and workable condition for a long time. Reeve’s Artists’ Depôts, Ltd., 53 Moorgate Street, London, supply an excellent qualityof ink for this purpose, in flexible tubes, at sixpence each, and the same firm can generally provide the rollers or squeegees used by photographers, which serve very well. In an emergency I have made serviceable ink with burnt cork, lamp soot, even shoe-blacking, using a good smooth and even cork as a roller. Wax casts, which should occasionally be made for study, can be made with the sheets of wax used greatly, at one time, for the making of artificial flowers. Excellent casts can also be made with putty, gutta-percha, sealing-wax, or hard paraffin, such as is used to encase the modern candle. Very excellent imprints of this kind have been left by burglars on candles they have used.

Some useful practical hints as to how finger-prints may be photographed and enlarged for police purposes are supplied by Inspectors Stedman and Collins, in an official work by Sir E. R. Henry,Classification and Uses of Finger-Prints; and others occur inDaktyloskopie, published in Vienna. Finger-marks on plated articles, when placed squarely with the camera in a strong side light, will appear light on a dark ground. The instructions in such a case are: “Focus sharply. Should, however, the mark be too faint to be clearly seen on the focussing screen, a piece of printed paper can be placed around the mark to focus by, but this should be removed before exposing the plate, otherwise halation will set in and obscure some of the lines in the finger-mark.” The plate done in this way gives a negative result, so that a transparency must be made and used so as to convert that into a positive print.

The fingers and thumbs may each be printed separately. For identification the serial order of fingers must beretained on the record. The official method in England is to print four fingers of each hand simultaneously, adding the right and left thumb to each respective section of the register. In addition, each thumb and finger is imprinted by rolling it slightly, which gives an enlarged area for the display of the more important linear elements in each finger pattern.

The prisoner signs this sheet, and also adhibits an imprint from his right forefinger under the signature.

The highly-glazed papers now so much used for half-tone photographic reproductions are not, in my experience, particularly good for ordinary impressions. The surface of any paper used should be fairly smooth, the texture firm, tough (not brittle), durable, and the colour white, as photographs for enlargement as judicial exhibits may be required.

Great care is now taken officially to secure the correct order of fingers, as on that the validity of the method depends, and the whole utility of the classification.

Inspectors Stedman and Collins, in the work just quoted, state that when finger-prints are required to be produced as evidence in a court of justice, “they are first enlarged 5 diameters direct with an enlarging camera. The negatives are afterwards placed in an electric light enlarging lantern, with which it is possible to obtain a photographic enlargement of a finger-print 36 inches square, such a photograph being as large as is ever likely to be required.”

In myGuide to Finger-Print Identification(p. 62) I have advocated uniform enlargement of all such exhibits on the decimal or metric system, and hope that international agreement on this point may be secured. Apartfrom criminal services its scientific utility would ultimately be very great. The objection that an English jury would dislike being confronted with the technicalities of a foreign and “mathematical” system is very easily met. An English jury—and no jury in the world is fairer or clearer-headed—would only, in any case, have to compare two figuressimilarly enlarged, one being that of the accused person’s fingers, taken while in custody, and the other, either a similar official record of another date, or a smudgy mark from some blotting-pad, window-pane, drinking-glass, bottle, or the like. The two exhibits, paired for comparison, would have been enlarged exactly on the same scale, whatever that scale might have been. For purposes of judicial comparison, therefore, English terms and English instruments might be used throughout, and no inconvenience could be felt by the most insularly prejudiced jury that could possibly be got together.

When a photographic enlargement has been made, it is necessary to be able readily to test its conformity with the enlargement to be compared with it, or if there be not strict agreement, to allow for and calculate the admitted discrepancy. This may easily be done by an application of the “rule of three.”

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