( xii ) 



the oldest type, but Escherich points out that it is unlikely 

 that a wingless form which had once acquired wings, would 

 again lose them, as in the case of wingless females. 



The following appear to be the stages in the phylogeny of 

 social insects : — 



1. Pre-social stage with a single kind of (^ and $. 



2. Social stage with a single kind of <^ and $, but the nesting 

 and nursing instincts have developed. 



3. Social stage with one kind of S and two or more kinds 

 of ?, all fertile, but those that build and hunt for food are 

 becoming less fertile. 



4. The present stage with one kind of ,^, a fertile form of $, 

 and one or more so-called " sterile " $ $ or ^ ^. These ^ ^ 

 are fertile with sufficient frequency to maintain (principally 

 through the c? (?) a representation of their characters in the 

 germ-plasm of the species. 



Weismann considers the egg-laying of the ^ ^ as too infre- 

 quent to influence the germ-plasm of the species. But it is 

 not so infrequent as he supposed, and not only c? 6 but ^ ^ 

 also are produced from these eggs ; so there is no reason why 

 the transmission of characters acquired by this caste should 

 be more improbable in ants than in other animals. 



It was supposed that unfertilised eggs always produced 

 males, but the experiments of Mrs. Comstock, Reichenbach, 

 Crawley, and recently my own, have shown that this is not 

 always the case, and that unfertilised eggs laid by workers 

 can produce workers, which considerably complicates matters. 



One other point which requires explanation is the fact that 

 true females are not reared in captivity, the only exception 

 we know of being recorded by the late Lord Avebury. 



I will not take up any more time now, but proceed with the 

 explanation of part of our chart. 



The male {ann) is the most fixed of the three typical phases, 

 even in genera where the females and workers are most differ- 

 ent in allied species. 



The micraner is smaller in stature than the normal male. 



The phthisaner is a pupal male which in the larval or semi- 

 pupal state has had its juices partially extracted by an Omsema 

 larva, and is unable to pass on to the imaginal stage. 



