24 ANIMAL AGGREGATIONS 



Volvox, when reproductive cells appear, and (2) colonies formed by 

 budding, as in the hydroids. 



2. Irreciprocal colonies must be recognized in which all members 

 do not contribute equally to the welfare of the whole. This is simply 

 illustrated by the case of a budding fresh-water Hydra, where the 

 new individual, the developing bud, has a parasitic relationship with 

 the mother. 



II. Secondary colonies develop by concrescence, as when the young 

 fresh-water sponges developing from different gemmules coalesce, 

 due to their proximity, and form one sponge body originating from 

 several gemmules. 



Beta. Societies of free individuals may be classified as follows: 



I. Societies based on a sexual or genetic foundation. 



I. Primary societies: families in which the young are descended 

 from a common father or a common mother or from common par- 

 ents, and which remain together from the very first. 



a) Reciprocal families in which all members benefit from the social 

 connection. 



(i) Sympaedia are composed of young of the same brood, but 

 without either of the parents present. Such societies may be homo- 

 morphic, as in the case of minnows or young birds, or heteromorphic, 

 as in bee colonies after the queen's swarm has departed. 



(2) Gynopaedia are composed of the mother and her immediate 

 offspring, which may again be divided between homomorphic and 

 heteromorphic groups. The former is represented by the mole crick- 

 ets {Gryllotalpa), the earwigs {Forficula), and many birds and mam- 

 mals; the latter group, by colonies of bees or ants. 



(3) Patrogynopaedia consist of a male and a female and their off- 

 spring, and may be divided into monomorphic, dinwrpliic, stud. poly- 

 morphic societies. Monogamous monomorphic societies of this sort 

 are common among birds where both parents remain with the young. 



Polygamous monomorphic families are similarly common among 

 many large animals, although monogamous families occur there, too, 

 as among foxes. In dimorphic patrogynopaedia the oftspring living 

 with the parents are true larvae, as, for example, in the passalid 

 beetles. The best example of a polymorphic colony of this type is 



