CORRELATION OF ORGANS. 243 



those changes of animals and plants which give rise to an. 

 absence of pigment (noticed previously) — in albinoes. The 

 want of the usual colouring matter goes hand in hand with 

 certain changes in the formation of other parts ; for example, 

 of the muscular and osseous system, consequently of organic 

 systems which are not at all ultimately connected with 

 the system of the outer skin. Very frequently albinoes are 

 more feebly developed, and consequently the whole structure 

 of the body is more delicate and weak than in coloured 

 animals of the same species. The organs of the senses and 

 nervous system are in like manner curiously affected when 

 there is this want of pigment. White cats with blue eyes 

 are nearly always deaf White horses are distinguished 

 from coloured horses by their special liability to form sarko- 

 matous tumours. In man, also, the degree of the development 

 of pigment in the outer skin greatly influences the suscepti- 

 bility of the organism for certain diseases ; so that, for 

 instance, Europeans with a dark complexion, black hair, 

 and brown eyes become more easily acclimatized to tropical 

 countries, and are less subject to the diseases there prevalent 

 (inflammation of the liver, yellow fever, etc.) than Europeans 

 of white complexion, fair hair, and blue eyes. (Compare 

 above, p. 150.) 



Among these correlations in the formation of difl*erent 

 organs, those are specially remarkable which exist between 

 the sexual organs and other parts of the body. No change 

 of any part reacts so powerfully upon the other parts of the 

 body as a certain treatment of the sexual organs. Farmers 

 who wish to obtain an abundant formation of fat in pigs 

 sheep, etc., remove the sexual organs by cutting them out 

 (castration), and this is indeed done to animals of both sexes, 



