PSYCHOLOGY. 43 



to obtain some special food, such as the excreta of Aphidae, etc. ; or 

 (2) that they purposely do not bring up females in captivity, as 

 they realize that there is not room for them, and that no marriage 

 flight could take place ; or (3) that the queen is unable, or will 

 not, lay eggs in captivity which will produce females. Supposi- 

 tions 2 and 3 appear to be rather too speculative in our present 

 state of knowledge for serious consideration. 



The following appear to be the stages in the phylogeny of 

 ants : 



1. A pre-social stage with a single kind of male and female. 



2. A social stage with a single kind of male and female, but 

 the nesting and nursing instincts have developed. 



3. A social stage with one kind of male, and two or more 

 kinds of female, all fertile, but those that build and hunt for 

 food are becoming less fertile. 



4. The present stage with usually one kind of male, a fertile 

 form of female, and one or more so-called " sterile " females, 

 or workers. These workers, however, are fertile with sufficient 

 frequency to maintain (principally through the male) a repre- 

 sentation of their characters in the germ-plasm of the species. 



Emery believes that a worker-like wingless form was the oldest 

 type of female both because the females in the Mutillidae are 

 wingless, and because in the Ponerinae, the most primitive sub- 

 family of ants, wingless females are more frequent than in the 

 higher subfamilies. As Escherich points out, however, it is un- 

 likely that a wingless form which had once acquired wings, would 

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



Weismann considered the egg-laying of the workers as too infre- 

 quent to influence the germ-plasm of the species. It is not, however, 

 so infrequent as he supposed, and as we have seen under Partheno- 

 genesis, not only males but workers also are produced from these 

 eggs ; so there is no reason why the transmission of characters 

 acquired by this caste should be either impossible or improbable. 



PSYCHOLOGY. 



Ants possess the senses of Smell, Touch, Taste, Sight, and pro- 

 bably Hearing in some form or other. 



The sense of smell, which is partly combined with that of touch, 

 is of the first importance to these insects, and undoubtedly resides 

 in the antennae. Ants are quickly attracted by some odours and 

 repelled by others ; they wave their antennae about when an 

 odorous substance is brought near to them, this being also the 

 case with quite blind species. When tapping anything with the 

 antennae, they probably obtain a combined sensation which 



