40 CALIFORNIA ACADEMY OF SCIENCES. 



taining food would be so strong as to compel the young 

 birds to ignore the example of their elders really reflects 

 upon his own assumption, for it seems difficult to con- 

 ceive that a new adjustment of such force as this instinct 

 is supposed to be, could be inherited in the course of a 

 few generations. The argument derived from the change 

 in nesting habits appears to have still less force. Mr. 

 Elliot assumes that nest building is an instinct, but this 

 assumption is unproven and has been emphatically 

 doubted by Wallace. In his Philosophy of Birds' Nests/" 

 he says: " At all events, till the crucial experiment is 

 made, and a pair of wild birds, raised from the egg with- 

 out ever seeing a nest, are shown to be capable of mak- 

 ing one exactly of the parental type, I do not think we 

 are justified in calling in the aid of an unknown and 

 mysterious faculty to do that which is so strictly analog- 

 ous to the house-building of savage men." 



Darwin has given many instances of the inheritance 

 of acquired habits which, however, have been skillfully 

 combated by William Platt Ball.f He cites, for ex- 

 ample, the inheritance by a colt of the paces of her 

 mother, but suggests that " selection of the constitu- 

 tional tendency to these paces, and imitation of the 

 mother by the colt, may have been the real causes." He 

 calls attention to the fact that the songs of birds are not 

 inherited, but are learned from their parents, and says: 

 ' If use-inheritance has not fixed the song of birds, why 

 should we suppose that in a single generation it has 

 transmitted a newly-taught method of walking or trot- 

 ting." He speaks of the supposed inheritance by dogs 

 of the intelligence acquired by contact with man, which 

 he explains thus: " But selection and imitation are so 



"Natural Selection, pp. 108-109. 



t Are the Effects of Use and Disuse Inherited ? Humboldt Library, pp 

 31-33. 



