660 APPENDIX B. 



matter how a pregnant Scotch greyhound is fed, or her pups after 

 they are born, they cannot be changed into English greyhounds : 

 the different germ-plasms assert themselves spite of all treatment. 

 But in these social insects the different structures of queens and 

 workers are determinable by differences of feeling. Therefore 

 the production of their various castes does not result from the 

 natural selection of varying germ-plasm. 



Before dealing with Professor Weismann's crucial case that 

 co -adaptation of parts, which, in the soldier-ants, has, he thinks, 

 arisen without inheritance of acquired characters let me deal 

 with an ancillary care which he puts forward as explicable by 

 "panmixia alone." This is the "degeneration, in the warlike 

 Amazon-ants, of the instinct to search for food." * Let us first 

 ask what have been the probable antecedents of these Amazon- 

 ants ; for, as I have above said, it is absurd to speculate about 

 the structures and instincts the species possesses in its existing 

 organized social state without asking what structures and in- 

 stincts it brought with it from its original solitary state and its 

 unorganized social state. From the outset these ants were pre- 

 datory. Some variety of them led to swarm probably at the 

 sexual season did not again disperse so soon as other varie- 

 ties. Those which thus kept together derived advantages from 

 making simultaneous attacks on prey, and prospered accordingly. 

 Of descendants the varieties which carried on longest the 

 associated state prospered most ; until, at length, the associated 

 state became permanent. All which social progress took place 

 while there existed only perfect males and females. What 

 was the next step ? Ants utilize other insects, and, among 

 other ways of doing this, sometimes make their nests where there 

 are useful insects ready to be utilized. Giving an account of 

 certain New Zealand species of Tetramorium, Mr. W. W. Smith 

 says they seek out underground places where there are " root- 

 feeding aphides and coccids," which they begin to treat as 

 domestic animals ; and further he says that when, after the 

 pairing season, new nests are being formed, there are " a few 

 ants of both sexes . . . from two up to eight or ten." f 

 Carrying with us this fact as a key, let us ask what habits will 

 be fallen into by the conquering species of ants. They, too, wih 

 seek places where there are creatures to be utilized ; and, finding 

 it profitable, will invade the habitations not of defenceless crea- 

 tures only, but of creatures whose powers of defence are inade- 

 quate weaker species of their own order. A very small 

 modification will affiliate their habits on habits of their proto- 

 types. Instead of being supplied with sweet substance excreted 



* Contemporary Revieio, September, 1893, p. 333. 



f T/ic Entomologist's Monthly Magazine, March, 1892, p. 61. 



