i SO ANTS. 



very few survive to become mothers of colonies. The vast majority, 

 after starting their shallow burrows, perish through excessive drought, 

 moisture or cold, the attacks of parasitic fungi or subterranean in- 

 sects, or start out with an insufficient supply of food-tissue in the 

 first place. Only the very best endowed individuals live to preserve 

 the species from extinction. 1 know of no better example of the sur- 

 vival of the fittest through natural selection. 



It is certain that the colonies of most species are founded in the 

 manner here described. It is certain, moreover, that all this is rendered 

 jiu-sible by the nutritive endowment of the queen. As the winged 

 germ of the species she has all the advantages that a yolk-laden has 

 over a comparatively yolkless egg. Now among the 5,000 known 

 species of ants we should expect to find considerable differences in the 

 quantity of nutriment stored up in the young queen. And this is un- 

 questionably the case. In some species the queens are of enormous 

 size, in others they are very small compared with the workers. And 

 since the queens of average dimensions are able to start colonies by 

 themselves alone, we should expect unusually large queens to accom- 

 plish even more, and very small ones less. This, too, is borne out by 

 observation. 



Unusually large queens are found in the genus Atta, a group of 

 American ants that raise fungi for food, and are, so far as known, 

 quite unable to subsist on anything else. The female Atta on leaving 

 the parental nest is so well endowed with food-tissue that she not 

 only can raise a brood of workers without taking nourishment, but 

 has energy to spare for the cultivation of a kitchen garden. 



Very different is the condition of certain queen ants poorly endowed 

 with food-tissue, especially of some whose bodies are actually smaller 

 than the largest workers of their species. Such queens are quite un- 

 able to bring up colonies unaided. They are, therefore, compelled 

 after fertilization to associate themselves with adult workers either of 

 their own or of a closely allied species. In the former case the queens 

 may either remain in the parental nest and omit the nuptial flight, or 

 return to the parental or to some other colony of the same species. In 

 either case they add to the reproductive energy of an already estab- 

 lished colony and thus prolong its life. If one of these poorly endowed 

 queens, however, happens to alight from her nuptial journey far from 

 any colony of her own species, she is obliged to associate with alien 

 workers. And in this case, according to the species to which she be- 

 longs, one of three courses is open to her: 



First, she may secure adoption in a small queenless colony of an 

 allied species. Here she is fed, lays her eggs, and the resulting larvae 



