Vlll CONTENTS. 



CHAPTER VIE 



IxSTDsCT. 



Instincts comparable with habits, but different in their origin- 

 Instincts graduated — Aphides and ants — Instincts variable- 



Domestic instincts, their origin — Natural instincts of the cuckoo 

 Molothrus, ostrich, and parasitic bees — Slave-making ants — 

 Hive-bee, its cell-making instinct — Changes of instinct and 

 structure not necessarily simultaneous — Difficulties of the 

 theory of the Natural Selection of instincts — Neuter or sterile 

 insects — Summary , Page 319 



