CHAPTER VII. 



POLYMORPHISM. (CONCLUDED.) 



" La conservation de ces animaux et la prosperite de leur famille ne pou- 

 voieiit done etre assurees que par I'etablissement d'un ordre particulier et noni- 

 breux d'individus qui suppleassent aux fonctions des meres et qui n'en eussent 

 nieine que les sentimens et les affections. La nature, en formant ici des neutres, 

 s'esl vue contrainte de s'ecarter de ses lois ordinaires, pour que son ouvrage 

 snbsistat, et sa prevoyance a modifie ses ressources selon les circonstances ou 

 Irs etres devoient etre places." Latreille, " Considerations Nouvelles et Gene-- 

 rales sur les Insectes Vivant en Societe," 1817. 



An extensive study of the structure and habits of ants must inevi- 

 tably lead to a certain amount of speculation concerning the phylo- 

 genetic development of their colonies. That these insects have had 

 communistic habits for ages is clearly indicated by the fact that all of 

 the numerous existing species are eminently social. There can be little 

 doubt, however, that they arose from forms with habits not unlike 

 those we find to-day in some of the solitary wasps, such as the Betnbe- 

 cida?, or in the remarkable South African bees of the genus Allodape. 

 Unlike other solitary wasps, the females of Bcinbc.r may be said to be 

 incipiently social, since a number of them choose a nesting site and, 

 though each has her own burrow, cooperate with one another in driv- 

 ing away intruders. Bcnibc.v has also taken an important step in the 

 direction of the social wasps not only in surviving the hatching of her 

 larvae, but also in visiting them from day to day for the purpose of 

 providing them with fresh insect food. 



At a very early period the ants and social wasps must have made a 

 further advance when the mother insect succeeded in surviving till 

 after her progeny had completed their development. This seems to 

 have led naturally to a stage in which the young females remained 

 with their mother and reared their progeny in the parental nest, thus 

 constituting a colony of a number of similar females with a common 

 and indiscriminate interest in the brood. This colony, after growing 

 to a certain size, became unstable in the same way as any aggregate of 

 like units, and must soon have shown a differentiation of its members 

 into two classes, one comprising individuals devoted to reproduction 

 and another devoted to alimentation and protection. In this division 

 of labor only the latter class underwent important somatic modification 

 and specialization, while the former retained its primitive and more 



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