REPAIR IN EVOLUTION 83 



that they are a reaction product, a forced revival of the 

 primitive panniculus. They act in the dartos, or deeper 

 layers of the scrotal dermis, at right angles to the ruga?, 

 and are something of a support. The pink colour of this 

 structure is due to the presence of these muscular fibres. 

 They are not connected in any way with the cremaster 

 muscle, and therefore are not affected by the cremasteric 

 reflex. In many senses the descent of the testes cannot 

 be called advantageous. It causes a weak spot, recognized 

 as such by men and animals. The Japanese wrestlers 

 are said to be trained from earliest youth to return 

 the testes into the inguinal canals. If the translation 

 of the testis from a safe place to an exposed one has had 

 any good results, they have been indirect and only 

 discoverable, though not yet discovered, over long periods 

 during which the change must have been disastrous to 

 many. To argue that they were advantageous to begin 

 with is to destroy the authority of reason. It is true 

 that at the present stage of human development an un- 

 descended testis rarely produces normal spermatozoa. But 

 to argue that the testes descended because the rise of 

 intra-abdominal pressure produced conditions incompatible 

 with racial continuance seems to ignore physical causation 

 in favour of a partially teleological explanation. It cannot 

 be argued that their present situation was always the best, 

 or that their early position was disadvantageous in face 

 of the fact that in elephants, seals, and walruses the testes 

 remain undescended, and that the boar's are at least in- 

 conspicuous and protected by normal skin tissues. As a 

 rough partial illustration, it may be said that though an 

 emigrant's descendants might do badly in his native village, 

 it does not follow that they might not have functioned 

 there successfully if their parent had not left it. 



