200 Tur Microscope. 
eral 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 animals 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 ro- 
dentia, for example, these cells are mostly arranged in pretty 
regular longitudinal lines, the medulla in the finest hairs being 
composed of buta 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, superimposed flatly, one on another, and overlapping 
so as to give the appearance of very fine irregular transverse 
strize on the surface of the hair, and a delicate serrated edge 
on the outer borders. The projection of these superficial cor- 
tical cells is only equal to the thickness of a single cell. On 
the other hand, in animal hair, where the cortex at all resem- 
bles that of human, the striz are coaser, 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 pro- 
jecting 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 in size. So 
also do hairs from the same animal, when collected at different 
seasons of the year, vary considerably both in length and 
thickness. Asa means of identity the diameter of the human 
hair is important when considered in connection with a con- 
siderable number of measurements made from hairs from a 
known source. Measurements 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 may be obtained, are of consid- 
erable value. 
