326 THE STORY OF THE EARTH AND MAN. 



Association, there was concealed a cutting sarcasrc 

 which the evolutionists felt. It reminded them that 

 the men who evolve all things from physical forces 

 do not yet know how these forces can produce the 

 phenomena of life even in its humblest forms. It 

 is true that the scientific world has been again and 

 again startled by the announcement of the produc- 

 tion of some of the lowest forms of life, either from 

 dead organic matter, or from merely mineral sub- 

 stances ; but in every case heretofore the effort has 

 proved as vain as the analogies attempted to be set 

 up between the formation of crystals and that of 

 organized tissues are fallacious. 



A second gap is that which separates vegetable and 

 animal life. These are necessarily the converse of 

 each other, the one deoxidizes and accumulates, the 

 other oxidizes and expends. Only in reproduction 

 or decay does the plant simulate the action of the 

 animal, and the animal never in its simplest forms 

 assumes the functions of the plant. Those obscure 

 cases in the humbler spheres of animal and vegetable 

 life which have been supposed to show a union of 

 the two kingdoms, disappear on investigation. This 

 gap can, I believe, be filled up only by an appeal to 

 our ignorance. There may be, or may have been, 

 some simple creature unknown to us, on the extreme 

 verge of the plant kingdom, that was capable of 

 passing the limit and becoming an animal. But no 

 proof of this exists. It is true that the primitive 

 germs of many kinds of humble plants and animala 



