Chap. IV. 
MANNER OF DEVELOPMENT. 
147 
being brought about, the internal pressure of the brain, 
will, also, have influenced the form of the skull; for 
many facts shew how easily the skull is thus affected. 
Ethnologists believe that it is modified by the kind of 
cradle in which infants sleep. Habitual spasms of the 
muscles and a cicatrix from a severe bum have per- 
manently modified the facial bones. In young persons 
whose heads from disease have become fixed either 
sideways or backwards, one of the eyes has changed 
its position, and the bones of the skull have been 
modified; and this apparently results from the brain 
pressing in a new direction . 74 I have shewn that with 
long-eared rabbits, even so trifling a cause as the lopping 
forward of one ear drags forward on that side almost 
every bone of the skull ; so that the bones on the oppo- 
site sides no longer strictly correspond. Lastly, if any 
animal were to increase or diminish much in general 
size, without any change in its mental powers ; or if 
the mental powers were to be much increased or 
diminished without any great change in the size of the 
body ; the shape of the skull would almost certainly be 
altered. I infer this from my observations on domestic 
rabbits, some kinds of which have become very much 
larger than the wild animal, whilst others have retained 
nearly the same size, but in both cases the brain has 
been much reduced relatively to the size of the body. 
Now I was at first much surprised by finding that in all 
these rabbits the skull had become elongated or dolicho- 
74 Schaatfhausen gives from Blumenbach and Busch, the cases of the 
spasms and cicatrix, in ‘ Anthropolog. Review,’ Oct. 1868, p. 420. Dr. 
Jarrold (‘ Anthropologia,’ 1808, p. 115, 116) adduces from Camper and 
from his own observations, cases of the modification of the skull from 
the head being fixed in an unnatural position. He believes that cer- 
tain trades, such as that of a shoemaker, by causing the head to be 
habitually held forward, makes the forehead more rounded and 
prominent. 
L 2 
