Index, 315 



PAGE 



Instinct, in connection with hibernation 125, 126 



in relation to special structure and function, as seen 

 in the rattlesnake, bee, wasp, hornets and spiders, 



12S-132 

 correlation between — form and color — examples, 

 grouse, ptarmigan-grouse, sage hen, spiders, 



caterpillars 132-134 



ready for most complex acts, when previous experi- 

 ence or observations are impossible. Illustration, 



The Seventeen Year Locust 134, 135 



not an entity 135. 13^^ 



seen in dependent species to secure the services of 



other species. Examples, ants, cow-bird 139 



for social life, after the breeding season is over 139 



for organization with a leader, or system of senti- 

 nels. Examples, crows, pigeons, pelicans, arctic 



tern 140, 142 



to build extensive works. Example, muskrat, bea- 

 ver 142, 145 



diversity of — structure and function — making divi- 

 sion of labor necessary. Examples, bees, wasps, 



ants, with Darwin's explanation 149-156 



connected with change of function in the mother. . . 158 



influence of domestication on ". 159 



of the young answering to the instincts of the 



mother 160 



as perfect in the beginning as now, proved by the 



very existence of some animals i6cy-i62 



requiring changes in other kinds of animals, or in 



plants, for the completion of its work 162 



the peculiar instinct of one stage of being as prepar- 

 atory to another, in which that instinct is lost — 



seen in the case of many insects 162 



changes with the seasons 163 



secures special relations of animals to plants, and to 

 each other. Examples — gall-fly, tent-moth, apple- 

 tree borer, oaks, roses, spruces, golden rod, 

 ichneumon insects, caterpillars, bot-fly 164-168 



