114 THE BEGINNINGS OF LIFE. 



however, combined with the less perfect condition 

 of the vascular system, are sufficient to account for 

 this want of integration in the plant, and the great 

 amount of independence shown by its individual 

 parts. 



Such are some of the principal differences in the 

 nature of the Life, or aggregate vital manifestations of 

 the members of the Animal and of the Vegetable King- 

 doms: and great as are the differences between the 

 phenomena of the higher and of the lower forms of 

 these, we may look for even still lower manifestations 

 of Life in a group of organisms whose characteristics, 

 whether structural or functional, are so little marked 

 as to make the most philosophic naturalists unable to 

 assign them a place amongst either the one or the other 

 of these Organic Kingdoms. 



It might have been expected, in accordance with the 

 doctrines of Evolution, that the lowest living things 

 would present characters of the most general descrip- 

 tion. They ought to be simply living things, without 

 visible organization, and should as yet present no 

 special characters by virtue of which a place might 

 be assigned to them either in the vegetable or in 

 the animal kingdom. The older naturalists thought 

 that every living thing must be either an animal 

 or a plant, and they accordingly ranged all organic 

 forms under one or other of these categories. But there 

 were certain of them whose characteristics were so in- 

 definite that they could really claim for themselves no 



