HAIR: 
MICROSCOPICALLY EXAMINED 
AND 
MEDICO-LEGALLY CONSIDERED. 
BY 
WILLIAM J. LEWIS, A. M, M. D„ F. R. M. S„ 
HAETFOBD, COTsTiT. 
Read at the Annual Convention of the American Society of Microscopists, 
in Rochester, N. Y„ Aug. 19th, 1884. 
Reprinted from the Proceedings of the Society. 
BUFFALO: 
Bigelow Brothers, Printers. 
1884. HAIR: MICROSCOPICALLY EXAMINED AND 
MEDICO-LEGALLY CONSIDERED. 
William J. Lewis, A. M., M. D., F. R. M. S. 
Two hundred years have elapsed since the compound microscope 
was devised. At first, and for a long time after it became known, it 
was regarded as an ingenious piece of .mechanism which afforded 
curious and wonderful revelations, or as an instrument with which 
the scientist could amuse his leisure hours, rather than a means 
through which might be unfolded lessons of practical utility. For 
me to say to this society that in the rapid advances of scientific 
pursuits, during later years, the microscope has become a powerful 
auxiliary of usefulness, is but to utter a truism. In every depart- 
ment of science it has become indispensable wherever accuracy is 
sought. The philosopher in his laboratory and the artisan in his 
work-room must resort to it frequently for its practical teachings. 
Its disclosures have revealed what otherwise were ever hidden mys- 
teries; have brought to full view that which else had always been 
obscure; have confirmed or dispelled many a dubious theory, and 
have established or disproved asserted facts which had rested upon 
suspicion only. The wide range of its usefulness has brought it 
prominently before the halls of justice, where, in the hands of the 
really skilled witness, it has proved a true friend of the court and of 
the community. 
In the field of forensic medicine, however, we necessarily must 
regard the microscope as being in the infancy of its service. I need 
only remind you that in this branch of our work no one subject, 
probably, has received such careful and thorough study as that 
of blood-stains ; and yet, after years of pains-taking research and 2 
experiment,—years of attentive labor by many of the brightest lights 
whose names and whose works have illumined the annals of sci- 
ence,—let me ask who, at the present day, aided by the most accu- 
rate instruments at our command, is able and willing to enter the 
witness-box and swear, without reserve, that a certain stain which 
has been submitted to him for an examination was made by human 
blood? If, then, in stains existing under many varying conditions 
and circumstances, but which are readily demonstrated to be blood, 
we are as yet unable to distinguish human from all animal blood 
with absolute certainty, we see how important it becomes to utilize 
all corroborative proof within our reach which may assist in deter- 
mining the kind of blood under inspection. And where may we look 
for this additional information? Evidently in the clot or stain 
itself. It probably seldom occurs in a murderous assault that blood 
stains, found on the weapons used, are formed without entangling 
in their substance more or less extraneous matter; and this material 
is not unfrequently hair, or textile fibers of one sort or another, 
which, when examined by the microscopist, will disclose presump- 
tive proof. Such evidence may assist in delivering into the hands 
of justice the perpetrator of a crime who might otherwise success- 
fully elude detection, or it may with equal force establish the inno- 
cence of a suspected person. What the microscopist may do to 
assist in determining questions of this nature, it is the purpose of 
this paper to briefly touch upon; and more especially to consider 
that feature to which we have alluded in speaking of hair and fila- 
mentous substances generally in their relation to legal medicine. 
If the object under observation is hair, it becomes at once 
necessary to determine, if possible, whether it is human or ani- 
mal; and if found to be of the latter kind, whether it is of its origi- 
nal, natural color, or has been stained by the dyer. To become 
practically familiar with the many varieties of fur, such as are in 
common use as articles of wearing apparel, and to recognize the 
changes wrought in hair by dyes to which it has been subjected, 
opens up an important and extensive field to the forensic micros- 
copist, and one which as yet has received comparatively little 
attention. 
The importance of closely inspecting weapons, and of carefully 3 
examining hair found upon them, may best be shown by a few illus- 
trative cases. 
In a case quoted by Dr. Taylor, a hatchet, having clotted blood 
and hair adherent to it, was produced as evidence against an accused 
person under whose bed the weapon had been found. This, with 
other circumstantial evidence, had turned public opinion strongly 
against the prisoner; but when the hair was examined it was found 
not to be human, but to have been taken from the body of some ani- 
mal. This circumstance led to a more complete sifting of the evi- 
dence, and the prisoner was acquitted. It turned out that the pris- 
oner had killed an animal with the hatchet, and had carelessly 
thrown the weapon under his bed. (Taylor s Med. Jurisp., Vol. /., 
p. pod.) Some years since a little girl was murdered in one of our 
large cities, and the appearance of wounds which had been inflicted 
upon her head indicated that the weapon used was some blunt 
instrument. A club stained with blood was found near by. The 
counsel for the accused person endeavored to show that the club 
had been used by the prisoner for the purpose of killing pigeons. 
The club was submitted to examination, and there were found in the 
clots thereon, and in the splintered portions of the weapon, certain 
hairs which were identified by others and myself as fine hairs from 
a human head. By comparison they were in every respect precisely 
like hair taken from the head of deceased. In the case of an al- 
leged murder in Connecticut, where the charred bodies of two 
women had been found in the debris of their dwelling which had 
burned to the ground, I was employed by the State to make an 
examination of certain pieces of half-burned cloth, some partly 
singed hair, and numerous other fragmentary substances. I found 
considerable blood in unburned portions of the cloth, but owing to 
the high temperature to which it had been exposed, the corpuscles 
could not be sufficiently restored to determine, even approximately 
by the aid of micrometry, whether they were of human or animal 
origin; and it was not* known whether there was an animal in the 
house at the time of the fire or not. I found, however, some hair 
which had been matted together by blood previous to its being 
heated, and was able in that case to show that the hair was from the 
head of an adult dark-complexioned person. One of the most im- 4 
portant features developed during this trial was the ability to 
that the blood in the meshes of the hair was ante-mortem* 
In distinguishing the various fibers from'which woven textures 
are made; in detecting, as is often possible, the characteristic action 
of certain dyes on textile fabrics; in demonstrating the peculiar 
twist of warp or consistence of woof in a given specimen,—we may, 
by means of comparison with textures from aVr established source, 
be able to form decided opinions relating to identity. In this pafier, 
however, which necessarily must be brief, I shall not enter at all 
upon the many changes which fibrous materials undergo in the pro- 
cess of manufacture. Nor shall I more than allude to the important 
medico-legal questions relating to human hair, such as whether it 
has been pulled out by violence, or fallen out by natural processes; 
whether it has been bruised or cut; nor shall I discuss the charac- 
teristics which frequently enable us to determine from what part of 
the body it comes. All of these points are treated in, our medico- 
legal text-books. I shall mainly confine my remarkf to the salient 
points of difference between human and animal hair, and the distin- 
guishing features of hair from those of the more common filaments 
which may be mistaken for it by the ordinary means of sight and 
touch. 
The principal filamentous substances which may be mistaken for 
hair are the finer fibers of jute, linen, silk, and cotton. These under 
a good glass are easily contradistinguished, and may be best dis- 
posed of in this paper by giving a short description of each, rather 
than by pointing out the special features wherein they differ 
from hair. 
Jute {Plate /., fig. 7), the liber fibers of the Cor chorus capsu- 
laris, an East Indian plant, when observed under a power of from 
one hundred and fifty to two hundred diameters, is at once seen to 
be of vegetable origin. The single fiber consists of a firm woody 
texture, with conical ends. The central axis is composed of long 
vegetable cells with blunt conical tips, separated from each other by 
* The blood, here referred to, was shown to have escaped from the victim during life, by 
presumptive evidence introduced during the trial; the author does not wish to be understood as 
believing there are any characteristic microscopical distinctions between so-called ante-mortem 
and post-mortem blood. 5 
delicate joint-markings at very regular intervals. The long, pliable 
character of the jute fiber, with its smooth regular surface and glossy 
appearance, enables it to be used quite extensively in the manufac- 
ture of so-called artificial hair, and also in many woven fabrics such 
as fancy table covers and mats. It is usually artificially colored 
before it comes into the hands of the microscopist, and may prove a 
valuable accessory to identification either of a person or a fabric. 
Linen (.Plate /., fig. j), the liber fibers of the Linurn resitatis- 
simutrt, employed for centuries in the manufacture of cloth, presents 
a strong woody consistence, round and attenuated to a point at the 
ends. Distinct joint-markings are seen at unequal distances. Linen 
fibers enter into the structure of many of our domestic garments, 
both in a dyed and uncolored state. Under favorable conditions it 
retains its microscopic characteristics for hundreds of years, and is 
not likely to be confounded with any other fiber employed in the 
manufacture of textile fabrics. 
Silk, an animal substance, secreted by the spinning organs of 
certain insects, presents, under an objective magnifying about two 
hundred and fifty diameters, the appearance of solid cylindrical or 
somewhat flattened filaments, free from markings of any kind. The 
boundary lines are clearly defined, and it is not liable to be mistaken 
for any of the fibers above mentioned. 
Cotton (Plate /., fig. £), the long, downy filaments from the 
capsules or pods of Gossipium, is one of the most familiar objects 
with which the practical microscopist is acquainted. His first efforts 
in mounting frequently present good specimens of cotton, regardless 
of what the object may have been intended to represent. The beauty 
of many a diatom mount, or of a desmid, has been spoiled by the 
unintentional presence of a cotton fiber on cover-glass or slide. But 
it is well to be able to recognize it in all the disguises it assumes in 
the course of manufacture and wear. Cotton consists of long, rib- 
bon-like bands, with somewhat thickened borders, and with a char- 
acteristic twist which would alone distinguish it from the filaments 
already mentioned. The flattening is due to a collapsing of the 
fiber when it dries, there being no thickening layer. There is little 
danger of cotton being mistaken for ordinary hair, though it may be 
for down or wool. Quite recently I examined a knife which was 6 
supposed to have been used by an accused person as the weapon in 
an alleged murder. On its blade were stains resembling dried blood, 
and in one of these stains were a number of hair-like filaments, 
which, under an ordinary pocket magnifier, closely resembled soft, 
downy human hair. Further examination showed them to be cotton. 
In cases of forensic microscopy, the importance of a careful exam- 
ination of all minute fibers found upon weapons cannot be too" 
strongly insisted upon. A case is related where a razor was found 
which belonged to a prisoner, and on which were some small fibers 
imbedded in blood, which, examined under a high magnifying power, 
proved to be cotton. In cutting the throat of his victim the mur- 
derer had also .cut through the cotton strings of her night-cap. The 
similarity of the cotton fibers on the razor belonging to the prisoner 
and those of the deceased woman’s night-cap was fully established. 
( Tidy's Legal Med., Vol. I.,p. 272) 
In another case, a knife which had been used to inflict a fatal 
wound, and which had been wiped afterward, contained in its de- 
pressions and irregularities, as well as between the layers of the 
handles, coagula of recent blood mixed with rust. One remarkable 
circumstance brought out by the microscope appeared to connect 
the weapon with the prisoner. In a small coagulum found on the 
knife, dried and fixed to the blade, were some woolen fibers of a 
peculiar purple-brown dye. These corresponded exactly to the 
fibers of the woolen jacket which the prisoner wore. {Taylor's Med. 
Jurisp., Vol. I., p. yogi) 
In examining hair for the sole purpose of determining whether it 
came from man or a lower animal, we shall find sufficiently charac- 
teristic differences in that portion known as the shaft, and we shall 
therefore limit our remarks to that part only, which, in fact, is often 
the only portion of the hair we are able to obtain in medico-legal prac- 
tice. The appearance of the hair-shaft varies considerably in different 
persons, as it does also in the same person upon different parts of 
the body; but there is, nevertheless, the same general structure, 
which enables us to identify it with little difficulty when under 
the microscope. Before entering upon the features distinguishing 
human from animal hair, it will save repetition if we first briefly 
refer to the general structure of the hair-shaft. 7 
When we examine a hair, properly mounted, under a low or me- 
dium power, we can usually discern at once its two principal ana- 
tomical parts, the cortex and medulla. The medulla, forming as it 
does a dark central axis in the hair, gives it the appearance of a 
tube,—an illusion which led some of the earlier observers into error. 
A thin transverse section of the shaft at once corrects this impres- 
sion, and shows the medulla to be composed of cells of variable size 
and shape. These cells usually contain dark, coarse spots, which 
were at one time supposed to be deposits of pigment, but have since 
been shown to consist of air. This can be easily demonstrated by 
allowing a longitudinal section of hair to soak in some volatile oil, 
when the air will be displaced by the oil, and the spots disappear, 
and again reappear upon evaporation of the oil. The size and shape 
of these medullary air cells, as we shall see later on, form one of the 
most noticeable distinctions between animal and human hair. 
The linear portion or cortex, which surrounds the medulla, is 
made up of flat and generally nucleated cells, the borders somewhat 
overlapping each other. By treating a human hair, preferably a 
white one, with caustic soda or potassa (Plate I., Jigs, i and 6), the 
cell walls become plainly visible; and by desiccation in warm nitric 
or sulphuric acid the individual cells may be obtained, showing 
oftentimes with beautiful distinctness their elongated nuclei,—and 
frequently, in dark hair, pigment markings. The cortex of a human 
hair, especially, is hard, tough, and yet elastic. This permits of 
brushing, combing, and of even much rougher treatment, without 
injury to its normally smooth contour. We would remark, in pass- 
ing, that this is a point of some value in forensic microscopy, as we 
frequently find dents of more or less depth in hair taken from 
weapons which have been used in assaults. Such dents or other 
injuries to the cortex, when observed in hair remaining on the vic- 
tim’s head, may lead to a presumption as to the kind of weapon 
used. 
With these remarks, we may now inquire into the characteristic 
distinctions which exist between human and animal hair. For the 
purpose of convenience they may be considered under the following 
heads, viz.: ist. The relative proportions of the cortical and medul- 
lary structures. 2d. The size, shape, and. arrangement of the 8 
medullary cells. 3d. The size, shape, and arrangement of the su- 
perficial cortical cells. 4th. The size and shape of the hair shaft. 
First.—The relative proportion of the cortical and medullary struc- 
tures. 
In animals, the medulla almost always forms a much larger pro- 
portion of the hair shaft than in man, though there are a number of 
exceptions to this general rule. In hair from certain Quadru?nana, 
the monkey for example {Plate //., fig. 6), the relative proportion 
of medulla is about the same as in the hair from man (Plate I., figs. 
1, 2, and 6), though its appearance is different. The stronger and 
denser the hair, the greater is the thickness of cortical structure; 
while conversely, the lighter and more pliable and spongy the hair, the 
greater is the proportion of the medulla. This rule is well illustrated 
in such typical examples as the pig’s bristles, intended more for pro- 
tection than warmth, with hard, horny cortex and proportionately 
small medulla; and on the other hand, the soft and pliable though 
coarse hair of the deer {Plate II., figs, ya andyb), with its thin, delicate 
cortex and full, spongy medulla, evidently constructed as much for 
warmth as for protection from violence. So universal is this rule, 
that, with a full knowledge of the life history of a given animal, we 
can form an opinion as to the relative proportion of cortical and 
medullary structures with considerable accuracy, even before we 
have made a microscopic observation. 
Second.— The size, shape, and arrangemettt of ittedullary cells. 
In human hair we find the medullary cells of variable size, irregu- 
larly round; that is, in such diverse shapes as globular cells assume 
when in close and crowded aggregations {Plate /., fig. 6). They 
differ in general appearance from the corresponding cells in most 
hairs of animal origin. They are smaller, more crowded, and unless 
specially prepared, less distinct than the medullary cells in animal 
hairs of the same diameter. In hair from most of our domestic ani- 
mals, we find the size, shape, and arrangement of these cells to be so 
totally unlike those in human hair, as to be contradistinguished at 
a glance, when properly mounted and viewed under a good glass by 
transmitted light. In the Rodentia, for example, these cells are 
mostly arranged in pretty regular longitudinal lines, the medulla in 9 
the finest hairs being composed of but a single row of more or less 
distinctly separated cells. 
Third.— The size, shape, and arrangement of the superficial cortical 
cells. 
In human hair these are thin, flat, and usually fusiform, super- 
imposed flatly one on another, and overlapping so as to give the ap- 
pearance of very fine, irregular, transverse striae on the surface of 
the hair, and a delicate serrated edge on the outer borders (Plate 
I., fig. 2). The projection of these superficial cortical cells is only 
equal to the thickness of a single cell. On the other hand, in ani- 
mal hair, where the cortex at all resembles that of human, the striae 
are coarser, more distinct, the lines more widely separated, and the 
edges generally more deeply serrated. In many hairs the projection 
of the superficial cortical cells is so great that instead of the striated 
appearance, we have a rough surface thickly studded with obliquely 
projecting points or spurs; or we may find the scales arranged in 
handsome whorls at regular intervals, as in the hairs of some bats. 
Fourth.— The size and shape of the hair shaft. 
Hairs from different parts of the same person or animal vary much 
in size. So also do hairs from the same ahimal, when collected at 
different seasons of the year, vary considerably both in length and 
thickness. As a means of identification, the diameter of human hair is 
important when considered in connection with a considerable number 
of measurements made from hairs from a known source. Measure- 
ments taken of the diameter of a hair for the purpose of ascertaining 
whether it is of human or animal origin are of little or no use; but 
measurements made of the thickness of the cortex and diameter of 
the medulla, whereby the relative proportion of each maybe obtained, 
are of considerable value. I present with this paper a table of such 
comparative measurements of hairs from quite a number of animals. 
This table gives the thickness of cortex and medulla, and diameter 
of hair-shaft, of both the coarse and fine or downy hairs. 10 
Coarse Hairs. 
Fine Hairs. 
Thickness 
of Cortex. 
Diam. of 
Medulla. 
Diam. of 
Hair Shaft 
Thickness 
of Cortex. 
Diam. of 
Medulla. 
Diam. of 
Hair Shaft 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
.0x72 
.0378 
.0722 
. . ..British Fox 
.0048 
.0098 
.0194 
.0096 
.0324 
.0516 
Sable. 
.0028 
.0136 
.0192 
.0118 
.0150 
.0362 
.0130 
.0598 
.0430 
.. .Zulu Antelope... 
.... English Otter... 
.0068 
.0026 
.0040 
.0080 
.0038 
.0060 
.0216 
.0090 
.0140 
.0200 
.0300 
.0380 
.0980 
.0070 
.0080 
.0220 
.0016 
.0424 
.0456 
.0016 
.0084 
.0116 
.0070 
. 0800 
.0940 
. . .Gray Squirrel. . . 
.0050 
.0090 
.0190 
.0020 
. 1080 
.1120 
...Northern Hare.. 
.0030 
.oho 
.0x70 
.0120 
.0340 
.0580 
.0050 
.0070 
.0170 
.0150 
.0330 
.0630 
.0050 
.0100 
0200 
.0080 
.0200 
.0360 
.0030 
.0150 
.0210 
.0180 
. 0200 
.0560 
.... Brown Bear.... 
N. A. Otter 
Australian Opossum. 
Zebra 
.0040 
.0120 
.0060 
.0080 
.0200 
.0100 
.0x60 
.0130 
.0160 
.0200 
.0800 
.0460 
.1120 
.0040 
.0170 
0990 
• 1330 
... Wapiti Deer ... 
.0030 
.0110 
.0170 
.0020 
. 2020 
.2060 
.0040 
.0360 
.0440 
.0030 
.1360 
. 1420 
.0070 
.0310 
.0450 
The shape of hair varies in persons and in animals. Hair from 
the human scalp is cylindrical and with smooth contour, while ani- 
mal hairs are of various shapes,—some oval, others branched, and 
many constricted in diameter at regular intervals along the shaft. 
Of the latter kind we may mention that of the mouse, in which we find 
the hair is round, and contains a number of rows of medulla cells 
which gradually diminish at the constricted part and increase in 
numbers as we examine the larger part, and so on through the entire 
length of the shaft, producing several symmetrical contractions and 
expansions in the hair. 
In conclusion, I wish to say that as, by following the general line 
of investigation indicated in this paper, we are able to distinguish 
human from animal hair, and from the few illustrative cases cited 
we have seen the great importance of such contradistinctions, allow 
me to express the hope that we may in future give more careful 
study to the examination of hairs and fibers entering into medico- 
legal case which may be referred to us as microscopists, and not con- 
fine our exclusive attention to examinations of blood-stains in the hope 
of being able to distinguish human from all animal blood, to the neg- 
lect of such other presumptive evidence as may be within our reach. 
* Hairs from the Hyena are very variable in size, there rarely being two of the same diameter 
in the same microscopical preparation. Plate I 
PEN SKETCHES OF HAIRS AND FIBERS EXPLANATION OF PLATE I. 
Fig. i. Human hair prepared and focused to show imbricated cortical scales. 
Fig. 2. Human hair showing medulla before the air is expelled, and illustrating 
relative proportions of cortex and medulla. 
Fig. 3. Transverse sections of human hair. 
Fig. 4. Sheep’s wool. 
Fig. 5. Linen fibers. 
Fig. 6. Human hair treated with caustic soda, showing medullary cells with 
their nuclei and the elongated nuclei of cortical cells. 
Fig. 7. Jute. 
Fig. 8. Cotton fibers. 
Fig. 9. Flax. EXPLANATION OF PLATE II. 
Fig. i. Fine and coarse hair from Mouse. 
Fig. 2. Flair from Skunk. 
Fig. 3. Hair from Brown Bear. 
Fig. 4. Fine hair from Raccoon. 
Fig. 5. Hairs fronji Gray Squirrel. 
Fig. 6. Flair from Red Monkey. 
Fig. 7. Hair from Deer. 7a longitudinal sec. 7b trans. sec. 
Fig. 8. Hair from Beaver. 
Fig. 9. Hair from African Wild Cat. 
Fig. 10. Hairs from Australian Opossum. 
Fig. 11. Flairs from Silver Fox. 11a, longitudinal sec. of coarse hair. 11b, 
transverse sec. of coarse hair. 
Fig. 12. Flair from Leopard. 
Fig. 13. Hair from Buffalo. Plate n 
PEN SKETCHES OF ANIMAL HAIRS