FINGER-PRINTS—THEIR EVOLUTION AND SIGNIFICANCE. 203 
study and examination, various methods have been adopted. 
Thus, wax of a suitable consistence has been used for 
receiving the impression, which in this: manner practically 
leaves a mould of the surface pressed upon the wax. A 
somewhat similar result, comparable to a photograph, is 
obtained by receiving the impressions upon a plate of glass 
which has previously been coated with a layer of fine soot 
from a smoky flame. Much better impressions may be 
made upon glass which has been coated with a smooth film 
of printer’s ink, as may easily be done by spreading the ink 
with a gelatine roller. (I have found this method of great 
service in taking impressions of the hands and feet of living 
monkeys and apes when no other method would have been 
of the slightest use owing to their varying conditions of 
terror, timidity, or temper !) 
The best impressions are those obtained by applying a 
smooth coating of printer’s ink to the part, and then 
transferring the ink to paper or a clean plate of glass. The 
ink is first smoothly spread upon a slab of porcelain, marble, 
glass, or metal, by means of a gelatine roller. Thereafter 
the digit or hand is applied to the ink, which is then 
transferred to a sheet of white paper or a plate of clean 
glass. My own experience is that impressions obtained on 
glass plates, if possible upon a size suitable for the lantern, 
are of enormous value in the labour of interpreting the 
prints, since they are so easily and comfortably enlarged on 
a screen, which may be of paper to facilitate drawing. 
The Skin. —From what has already been said, it will be 
evident that “finger-prints ” record certain appearances pre- 
sented by the skin. Now, on the palm of the hand and sole 
of the foot, the skin possesses two sets of distinctive and 
highly characteristic appearances. First, it shows a series of 
transverse and oblique grooves or foldings which affect the 
entire thickness of the skin, and are due to the action of the 
various muscles connected with the hand and foot. These 
are named integumentary grooves, and they are nothing 
more than the creases which result from frequently repeated 
folding of the skin along very definite and precise lines, 
following upon the repeated contraction of muscles whose 
positions and attachments admit of no uncertainty in their 
