DIVISION OF ANIMAL KINGDOM. 261 



form of nucleated cells, which manifest the common or- 

 ganic characters, but are without the true distinctive 

 superadditions of either kingdom. 



Our difficulties are yet far from a satisfactory adjust- 

 ment ; only very lately it has been affirmed by Dr. 

 Hartig that amoeba may be produced by the transforma- 

 tion of the ' antherozoids* of Chara, Marchantia, or Mosses, 

 and that, in their turn, they became metamorphosed, first 

 into Protococci or other unicellular Algae, and then into 

 articulated Algae. This consideration takes us back to the 

 arguments adduced by Mr. Carter, in favour of the analogy 

 between the nucleus of the cell of Chara and that of the 

 Rhizopodous cell, which will be found given at some length 

 in the preceding chapter. 



If" writes Mr. Lewes " plants and animals present 

 difficulties in our early attempts to distinguish them from 

 each other, they are all distinguishable from minerals 

 by a triple phenomenon assimilation, reproduction, and 

 death. The same elements are common to the animate 

 and the inanimate kingdoms ; many forms are common to 

 both : but no mineral assimilates that is to say, grows 

 by the intersusception of foreign material, which it con- 

 verts into its own substance j no mineral dies, as the ine- 

 vitable termination of a cycle of internal changes. 



" Nutrition belongs to all animals ; but although the 

 final and fundamental act assimilation is the same in 

 all, the preparatory and intermediate processes are singu- 

 larly varied. Thus the Infusoria, or unicellular organisms, 

 have no special organ whatever, the only distinction 

 between the parts is that of ' envelope' and * contents ;' by 

 its envelope the animal absorbs, feels, and moves; by its 

 contents it assimilates. An Amoeba, for example, may be 

 looked upon as an assimilating surface having the property 

 of contractility : nothing more. Gradually we observe 

 fresh distinctions of parts : a hole is formed, by way of 

 mouth; then we have two holes, one for reception, the 

 other for rejection of food. Then the mouth becomes fur- 

 nished with jaws ; then with rudimentary teeth ; after- 

 wards with actual teeth, but all of one type ; finally the 

 teeth themselves become distinguished into incisors and 

 molars ; a tongue is added to the mouth ; so that from a 



