S EVOLUTION IN THE PAST 



if similar forms are now in existence no microscope, however 

 powerful, would be likely to reveal them. Food must have 

 consisted of simple chemical compounds ; and there is no 

 reason to think that the organisms disclosed any character- 

 istics, stamping them either as plants or animals. They may 

 rather be thought of as a highly generalised stock from which 

 plants and animals were in course of time to be evolved. 

 The condition of things was Utopian ; peace abounded and 

 equality. 



Very long times may have elapsed before this primitive 

 condition of things became varied by the emergence of 

 definite life-forms. Probably the earliest organisms of distinct 

 character were minute one-celled plants, possessing no defined 

 root, stem, or leaf. Here was the foundation laid of the 

 Kingdom of Plants. 



In course of time another divergence from the vague 

 primeval stock took place ; and minute animals, one-celled 

 and shapeless, made their appearance. These probably 

 moved about the shallows without the aid of any definite 

 locomotive appliances, and subsisted chiefly on their vegetal 

 cousins. The foundation of the Kingdom of Animals was 

 laid ; but Utopia was gone. 



From the primitive plant-stock, it may be supposed, minute 

 one-celled growths of a mixed algae and fungus description 

 in course of time made their appearance. Whilst the minute 

 animals doubtless became varied chiefly by more active forms 

 aided in locomotion by tiny thread-like outshoots of the cell. 



All plants and animals, no doubt, for long consisted merely 

 of one-celled organisms. Food could be taken in, and waste 

 expelled at any part of the surface ; and multiplication 

 was effected by the cell splitting in two, and each portion 

 becoming a complete self-sufficing cell. Such forms of life, 

 indeed, still exist in great abundance. 



Life on earth could clearly make no great advance towards 

 its destined future so long as all organisms remained in a 

 unicellular condition. It may be assumed, therefore, that in 

 course of time cases occurred in which the two portions of the 

 dividing cell did not become completely separated from one 

 another. And these two-celled forms, by continued multi- 



