Chap. IV.] MANNER AND DEVELOPMENT. 113 



nearly their whole lives in canoes, with their lower 

 extremities motionless. Other writers have come to a 

 similar conclusion in other analogous cases. Acpording 

 to Cranz, 23 who lived for a long time with the Esquimaux, 

 "the natives believe that ingenuity and dexterity in seal- 

 catching (their highest art and virtue) is hereditary ; there 

 is really something in it, for the son of a celebrated seal- 

 catcher will distinguish himself though he lost his father 

 in childhood." But in this case it is mental aptitude, 

 quite as much as bodily structure, which appears to be 

 inherited. It is asserted that the hands of English labor- 

 ers are at birth larger than those of the gentry. 24 From 

 the correlation which exists, at least in some cases, 25 be- 

 tween the development of the extremities and of the jaws, 

 it is possible that in those classes which do not labor much 

 with their hands and feet, the jaws would be reduced in 

 size from this cause. That they are generally smaller in 

 refined and civilized men than in hard-working men or 

 savages, is certain. But with savages, as Mr. Herbert 

 Spencer 26 has remarked, the greater use of the jaws in 

 chewing coarse, uncooked food, would act in a direct man- 

 ner on the masticatory muscles and on the bones to which 

 they are attached. In infants long before birth, the skin 

 on the soles of the feet is thicker than on any other part 

 of the body ; 27 and it can hardly be doubted that this is 

 due to the inherited effects of pressure during a long 

 series of generations. 



It is familiar to every one that watchmakers and en- 

 gravers are liable to become short-sighted, while sailors 

 and especially savages are generally long-sighted. Short- 



23 'History of Greenland,' Eng. translat. 1767, vol. i. p. 230. 



24 ' Intermarriage.' By Alex. Walker, 1 838, p. 377. 



25 • The Variation of Animals under Domestication,' vol. i. p. 173 

 96 ' Principles of Biology,' vol. i. p. 455. 



,7 Paget, ' Lectures on Surgical Pathology,' vol. i, 1853, p. 209. 

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