ages!

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ADDITIONS.

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ADDITION I.

At the end of the article Canities, in Class I. 2. 2. 11. please to add
the following:

As mechanical injury from a percussion, or a wound, or a caustic, is liable
to occasion the hair of the part to become grey; so I suspect the
compression of parts against each other of some animals in the womb is
liable to render the hair of those parts of a lighter colour; as seems
often to occur in black cats and dogs. A small terrier bitch now stands by
me, which is black on all those parts, which were external, when she was
wrapped up in the uterus, teres atque rotunda; and those parts white, which
were most constantly pressed together; and those parts tawny, which were
generally but less constantly pressed together. Thus the hair of the back
from the forehead to the end of the tail is black, as well as that of the
sides, and external parts of the legs, both before and behind.

As in the uterus the chin of the whelp is bent down, and lies in contact
with the fore part of the neck and breast; the tail is applied close
against the division of the thighs behind; the inside of the hinder thighs
are pressed close to the sides of the belly, all these parts have white
hairs.

The fore-legs in the uterus lie on each side of the face; so that the feet
cover part of the temples, and compress the prominent part of the upper
eye-brows, but are so placed as to defend the eye-balls from pressure; it
is curious to observe, that the hair of the sides of the face, and of the
prominent upper eye-brows, are tawny, and of the inside of the feet and
legs, which covered them; for as this posture admitted of more change in
the latter weeks of gestation, the colour of these parts is not so far
removed from black, as of those parts, where the contact or compression was
more uniform.

Where this uterine compression of parts has not been so great as to render
the hair white in other animals, it frequently happens, that the
extremities of the body are white, as the feet, and noses, and tips of the
ears of dogs and cats and horses, where the circulation is naturally
weaker; whence it would seem, that the capillary glands, which form the
hair, are impeded in the first instance by compression, and in the last by
the debility of the circulation in them. See Class I. 1. 2. 15.

This day, August 8th, 1794, I have seen a negro,