SUMMARY 297 



factory to look at such instincts as the young- cuckoo ejecting 

 its foster-brothers, — ants making slaves, — the larvae of ichneu- 

 monida; feeding within the live bodies of caterpillars, — not 

 as specially endowed or created instincts, but as small conse- 

 quences of one general law leading to the advancement of all 

 organic beings, — namely, multiply, vary, let the strongest live 

 and the weakest die. 



