FORENSIC MICROSCOPY. 135 
to hematin (methemoglobin) may show a spectrum 
with the combined bands of both. The spectroscopic 
test is, -of course, given by the blood of any red-blooded 
anima!. It is extremely delicate and has yielded posi- 
tive results with stains over a hundred years old. 
4. The Study of Finger-prints.—The identification of 
individuals, so important not only in criminology but in 
a multitude of civil and criminal cases, has been greatly 
facilitated by the anthropometric system of M. Ber- 
tillon. This rests upon the principle that variations in 
the proportions of the body, when a number of separate 
features are measured, are so characteristic that a defi- 
nite formula may be obtained from them, which shall 
differentiate each individual from any other. Commonly 
the length and breadth of the head and the length of the 
left middle finger, the left forearm, and the left foot form 
a primary basis for classification to which other general 
characteristics and special individual peculiarities may 
be added ad infinitum. 
The use of the finer details of the structure of the skin 
to supplement the Bertillon system was first suggested 
by the distinguished English biologist, Francis Galton, 
though Sir William Herschel had previously used finger- 
prints as a means of personal identification. Recently 
Professor H. H. Wilder’s investigations have shown the 
great importance of these structures in the study of 
heredity. If the bulb below the tip of the finger be 
pressed first upon a metal surface covered with a thin 
film of printer’s ink, and then upon a paper or card, 
a permanent record will be obtained of the arrangement 
