CHAPTER LXI 

 ASSOCIATION OF ANIMALS COLONIES 



Having considered the chief sorts of relation which exist 

 between animals and plants, we have now to deal with the asso- 

 ciation of individual animals, whether of the same or different 

 species. In the sections on Food and Defences (volume ii) one 

 kind of connection has been treated at considerable length, i.e. 

 that which links carnivorous (and to some extent omnivorous) 

 forms with their prey, and we have seen that the bodily structure 

 of both attackers and attacked have been more or less perfectly 

 adapted to the exigencies of attack and defence. Another chapter 

 of the same story will engage our attention rather later on, when 

 Animal Parasites receive consideration, but it will be convenient 

 in the meantime to enter into some particulars regarding other 

 kinds of relation. 



Animals of the same species may be associated together in 

 three chief ways, conveniently described under the headings of 

 Colonial Animals, Social Animals, and Courtship and Mating of 

 Animals. 



COLONIAL ANIMALS 



COLONIAL ANIMALCULES (PROTOZOA). The minute and lowly 

 creatures known as Animalcules are distinguished from animals 

 higher in the scale by the fact that they are single cells or units 

 of structure, i.e. they are unicellular. They propagate, as a rule, 

 by splitting (fission) or budding (gemmation), and in a number 

 of species the new individuals which thus come into existence 

 remain connected together, forming a colony (fig. 1089). The 

 members of such a colony are usually all alike, each of them 

 performing all the duties of life for itself, and species for which 

 this is true have therefore been described as " physiologically 

 unicellular ". Most of them are fixed, as, for instance, in Epistylis 



