466 LEON AUGUSTUS HAUSMAN 
face of the hair shaft presents an alternating series of transverse 
ridges and transverse depressions, due to the overlapping, imbri- 
cate cuticular scales. The method devised for making clear the 
outline of the scales is, in principle, to lodge finely divided color- 
ing matter in all of these transverse depressions, leaving the ele- 
vations uncolored. This was accomplished in the following man- 
ner: The hair shaft was first washed in a solution composed of 
equal parts of 95 per cent alcohol and ether, to free its surface 
from oily matter. It was then heated very slightly or fanned 
gently, to insure complete drying, and then immersed in a 95 
per cent alcoholic solution of gentian violet or safranin. After 
remaining in this solution for a minute or more, it was removed 
with forceps and held in a gentle draft of air or in the current of 
warm air rising from a bunsen flame until the alcohol had com- 
pletely evaporated. The gentian violet or safranin, it was found, 
had been deposited from the solution and had gathered in all the 
transverse depressions on the surface of the hair, thus marking 
out clearly the outline, in sharp color, of every cuticular scale. 
The most delicate scale sculpturings which are capable of deter- 
mination upon the finest of the hairs with the immersion objec- 
tives were by this method of treatment rendered plain, though 
for the very finest of the hairs this method was combined with 
examination under oblique illumination, hereafter described. It 
was found, however, that while this method gave almost ideal 
results with some hairs at the very first trial, it was necessary 
with other hairs to subject them to the processes again and again 
before the evaporation of the alcohol deposited the pigment 
uniformly in the cuticular grooves over any considerable portion 
of the hair surface. 
Other stains which go easily into solution in the 95 per cent 
alcohol and are readily deposited upon its evaporation, such as 
iodine (with potassium iodide), methyl green, methyl and methyl- 
ene blue, and toluidin blue, were also used, but for some unknown 
reason the best success was obtained with the gentian violet and 
safranin. 
In the case of those hairs in which the scales are so prominent 
as to project notably out from the shaft, a very striking profile 
