Unicellular and Multicellular Animals 



of water, and a plentiful supply of this is one of the essentials for 

 the continuance of active life. Therefore, before the conquest 

 of the dry land could be accomplished, devices had to be evolved 

 both for maintaining and for conserving the water supply — roots 

 in the plant ; in the animal, some method of locomotion by land 

 or air, so that water could be frequently reached ; protection 

 against evaporation, in the form of a skin, in both ; and numerous 

 other special devices. Add to this the fact that locomotion on 

 land presents much greater difficulties than that in water, and it will 

 hardly occasion surprise that vast ages were yet to be required 

 before the Evolution process could produce a land animal. 



A striking analogy may be drawn between animal Evolution, 

 from this point onwards, and social Evolution. In the latter 

 case we begin with men, brought by a slow process of Evolution 

 to a high state of individual perfection, living in a state of savage 

 individualism. Each thinks and acts for himself, provides his own 

 food, raiment, and dwelHng ; constitutes his own standing army 

 and police. From this condition of affairs there has gradually 

 been developed the modern social arrangement, by which each 

 individual helps to carry out some distinctly special part of work 

 for the community — be it wheat-growing, cloth-weaving, brick- 

 laying, or the arresting of burglars — and trusts to the community 

 for his requirements in all other directions. These requirements 

 themselves have so multiplied during the course of social Evolution 

 that innumerable forms of activity have sprung up between those 

 occupations which provide the original necessities of life. The 

 essence of the whole process has been co-operation and the division 

 of labour. 



In the story of animal Evolution we have reached a point where 

 a highly perfected individual cell has been produced, which carries 

 out for itself, and for itself alone, all the activities of life. From 

 now onwards,, co-operation and specialisation are the watch- 

 words of progress. There is a clubbing together, first of a few 

 cells, then of hundreds, and finally of millions upon millions, to 

 form the bodies corporate which we recognise as individual higher 

 animals. Division and distribution, subdivision and further 



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