Tue Microscope. 199 
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. 
With these remarks we may now inquire into the charac- 
teristic distinctions which exist between human hair and animal 
hair. For the purpose of convenience they may be considered 
under the following heads, viz: First, The relative proportions 
of the cortical and medullary structure. Second, The size, 
shape and arrangement of the medullary cells. Third, The 
size, shape and arrangement of the superficial cortical cells. 
Fourth, The size and shape of the hair shaft. First, the rela- 
tive proportion of the cortical and medullary structures. 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 
quadrumana, the monkey for example, the relative proportion 
of medulla is about the same as in the hair from man, though 
its appearance is different. The stronger and denser the hair, 
the greater is the thickness of cortical structure, while con- 
versely the lighter, 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 bristle, intended more for 
protection than warmth, with its hard, horny cortex and pro- 
portionately small medulla, and on the other hand the soft, 
pliable though coarse hair of the deer, with its thin, delicate 
cortex and full spongy medulla, evidently constructed as much 
for warmth as 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, 
size, shape and arrangement of medullary cells. In buman 
hair we find the medullary cells of variable size, irregularly 
round, that is, in such diverse shapes as globular cells assume 
when in close and crowded aggregations. They differ in gen- 
