90 The Study of Animal Life PART i 



" worms," we see that the habit of forming colonies is 

 common. Every sponge is a simple sac to begin with, 

 but it buds off others like itself, and the result is a coherent 

 colony. A zoophyte is not one individual, but a connected 

 colony of individuals. Throughout the colony there is one 

 life ; all the individuals have a common origin, and all are 

 members one of another. In varying degrees of perfection 

 the life of the whole is unified. Moreover, the unity is 

 often increased, not diminished, by the fact that the indivi- 

 duals are not all alike. There is division of labour among 

 them ; some may feed while others reproduce, some feel 

 much while others may be quite callous. Thus, as we 

 already mentioned, the Portuguese Man -of- War, a colony 

 of small jellyfish -like individuals, has much division of 

 labour, and yet there is much, though by no means perfect, 

 unity of life. 



Our second conclusion is that among many animals 

 beginning with sponges and ending with the sea-squirts, 

 which are acknowledged to be animals of high degree 

 the habit of forming colonies is common, and that these 

 colonies, though organically continuous, illustrate the essence 

 of society ; for in them many individuals of common descent 

 and nature are united in mutual dependence and help- 

 fulness. 



The next step towards an understanding of the social 

 relations of animals is very different from that in which we 

 have recognised the habit of forming colonies. The factor 

 which we have now to acknowledge is the love of mates. 

 This also has its history, this also has its prophecies among 

 the firstlings, but we shall simply assume as a fact that 

 among crustaceans and insects first, in fishes and amphi- 

 bians afterwards, in reptiles too, but most conspicuously 

 among birds and mammals, the males are attracted to the 

 females, and in varying degrees of perfection enter into 

 relations of mutual helpfulness. The relations and the 

 attractions may be crude enough to begin with, but perhaps 

 even we hardly know to what heights of devotion their 

 highest expressions may attain. To mere physical fondness 

 are added subtler attractions of sight and hearing, and 



