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 burn 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 Schaaff hausen 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 bis 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. 



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