FITNESSES 



for the prolonged ante-natal life of the young ; 

 the so-called " egg-tooth " at the end of a young 

 bird's bill is adapted to the single operation of break- 

 ing the egg-shell and so on throughout the whole 

 of the animate world. 



The Mole 



As a particular instance of fitnesses, let us take a 

 common animal like the mole, " the little gentleman 

 in the velvet coat," who long ago discovered the 

 possibility of a subterranean life for a warm-blooded 

 animal, and disturbed the earthworms in the retreats 

 where they had for ages enjoyed peaceful security. 

 What a bundle of adaptations the creature is ! 

 The out-turned hand has become a powerful shovel, 

 aided by the presence of an extra bone, the sickle, 

 to the inner side of the thumb ; the shoulder-girdle 

 is very strong and the breast muscles are those of an 

 athlete ; the long muscular sensitive snout, which 

 probes the way, is strengthened by a special bone 

 near the tip ; the absence of the external trumpet 

 of the ear means a reduction of friction ; the minute 

 eyes are well hidden among the hair and thus 

 saved from being rubbed ; and there must be some 

 special advantage, too, in the way the hairs stand 

 out vertically like the pile on velvet. The eye 

 is not well finished, as an instrument -maker might 

 say the lens in particular being only half -made, 

 and the optic nerve far from well developed but 

 the mole is quite aware of the difference between 

 light and darkness, and its eyesight is probably 

 just as good as it needs to be. 



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