Cii.i.Vll. INSTINCT. 201 



CHAPTER VII. 



INSTINCT, 



Instincts coniparnl)lo with Ilabiis, but difTcront in their Orii^in— Inptincls £;radu.ited 

 — Aphides and Ants— Instincts vnriable— DomcBtic Instincts, tlicir Origin— Nat- 

 ural luHtincta of tlic Cuckoo. Ostrich, and Parasitic Bees— Slave-niakin:,' Ants— 

 Hive-bee, its cell-inakini; instinct— Changes of Instinct and Structure not neces- 

 sarily simultaneous- DilDculties of the Theory of the Natural tjelectiou of lu- 

 btincta— Neuter or Sterile Insects — Summary. 



Instincts might have been worked into the previous chap- 

 ters ; but I thought that it would be more convenient to treat 

 the subject separately, especially as an instinct so wonderful as 

 that of the construction of the comb by the hive-bee will prob- 

 ably have occurred to many readers, :is a difficulty sufficit-nt to 

 overthrow the whole theory. I must premise that I have 

 notliing to do with the origin of tlic primary mental powers, 

 any more than I have with that of life itself. We are con- 

 cerned only with the diversities of instinct and of the other 

 mental qualities of animals Avithin the same class. 



I will not attempt any definition of instinct. It would be 

 easy to show that several distinct mental actions are commoidy 

 embraced by this term ; but every one underst;uids what is 

 meant, when it is said that instinct impels the cuckoo to mi- 

 grate and to lay her eggs in other birds' nests. An action, 

 which we ourselves should require experience to enable us to 

 perform, when performed by an animal, more especially by a 

 very young one, without any experience, and when performed 

 by many individuals in the same way, without their knowing 

 for what purpose it is performed, is usutilly said to he instinc- 

 tive. But I could show that none of these cliaracters of in- 

 stinct are universal. A little dose, as Pierre Hubcr expresses 

 it, of judgmtMit or rea.son, often comes into play, even in ani- 

 mals low in the scale of nature. 



Frederick Cuvier and several of the older m('tai)hysicians 

 have compared instinct with habit. This comparLsou gives, I 

 think, an accurate notion of the frame of mind under which 

 an instinctive action is performed, but not necessarily of its 



