OBJECTIONS TO THE THEORY OF DESCENT. 329 



danger-chuckle, they will run (more especially young tur- 

 keys) from under her, and conceal themselves in the sur- 

 rounding grass or thickets ; and this is evidently done 

 for the instinctive purpose of allowing, as we see in wild 

 ground-birds, their mother to fly away. But this instinct 

 retained by our chickens has become useless under domes- 

 tication, for the mother-hen has almost lost by disuse the 

 power of flight. 



Hence, we may conclude that, under domestication, 

 instincts have been acquired, and natural instincts have 

 been lost, partly by habit, and partly by man selecting 

 and accumulating, during successive generations, peculiar 

 mental habits and actions, which at first appeared from 

 what we must in our ignorance call an accident. 



INNUMERABLE LIXKS NECESSARILY LOST. 



Origin of The mam cause of innumerable interme- 



Species, diate links not now occurring everywhere 

 pase ' throughout nature depends on the very pro- 

 cess of natural selection, through which new varieties 

 continually take the places of and supplant their parent- 

 forms. But just in proportion as this process of exter- 

 mination has acted on an enormous scale, so must the 

 number of intermediate varieties, which have formerly 

 existed, be truly enormous. Why, then, is not every geo- 

 logical formation and every stratum full of such inter- 

 mediate links ? Geology assuredly does not reveal any 

 such finely-graduated organic chain ; and this, perhaps, 

 is the most obvious and serious objection which can be 

 urged against the theory. The explanation lies, as I be- 

 lieve, in the extreme imperfection of the geological record. 

 In the first place, it should always be borne in mind 

 what sort of intermediate forms must, on the theory, have 



