Chap. 49.] 
THE BRAI1S-. 
47 
from their birth. There are some animals, also, that are natu- 
rally bald, such as the ostrich, for instance, and the aquatic 
raven, which last has thence derived its Greek^^ name. It is 
but rarely that the hair falls off in women, and in eunuchs 
such is never known to be the case ; nor yet does any person 
lose it before having known sexual intercourse.^^ The hair 
does not fall off below the brain, nor yet beneath the crown of 
the head, or around the ears and the temples. Man is the 
only animal that becomes bald, with the exception, of course, 
of such animals as are naturally so. Man and the horse are 
the only creatures whose hair turns grey ; but with man this is 
always the case, fii'st in the fore-part of the head, and then in 
the hinder part. 
CHAP. 48. THE BOXES OF THE HEAD. 
Some few persons only are double- crowned. The bones of 
the head are flat, thin, devoid of marrow, and united with su- 
tures indented like a comb. "When broken asunder they can- 
not be united, but the extraction of a small portion is not ne- 
cessarily fatal, as a fleshy cicatrix forms, and so makes good 
the loss. We have already mentioned, in their respective^ 
places, that the skull of the bear is the weakest of all, and 
that of the parrot the hardest. 
CHAP. 49. THE BRAIK. 
The brain exists in all animals which have blood, and in 
those sea animals as well, which we have already mentioned 
as mollusks, although they are destitute of blood, the poly- 
pus, for instance. Man, however, has, in proportion to his 
body, the most voluminous brain of all. This, too, is the 
most humid, and the coldest of all the viscera, and is enve- 
loped above and below with two membranous integuments, 
for either of which to be broken is fatal. In addition to these 
facts, we may remark that the brain is larger in men than in 
81 See B. V. c. 29. 
82 i^aXaicpOKupa^. See B. X. C. 68. 
He borrows this from Aristotle. 
8* B. yiii. c. 54, and B. x, c. 58. The skull of the bear is not thinner 
or weaker than that of other animals of its own size ; but the skull of the 
parrot, in proportion to those of other birds, is remarkably hard. 
