46 THE EVOLUTION OF MAN. 



organic phenomena of life, of nutrition, reproduction, sensa- 

 tion, and movement. If we tried to construct, a priori, the 

 simplest conceivable organism, we should always be com- 

 pelled to fall back upon such a Monera. 



Although in all real Monera the body consists merely 

 of such a small living piece of plasson, yet, among the 

 Monera, which have been observed in the sea and in 

 fresh water, we have been able to distinguish several dif- 

 ferent genera and species, varying in the mode in which their 

 tiny bodies move and reproduce. In the ways in which 

 movement is accomplished very noticeable differences exist. 



Fig. 163. — A Moneron (Protamceba) in the act of reproduction : A, the 

 whole Moneron, which moves, like the ordinary Amoeba, by means of variable 

 processes ; B, a contraction round its circumference parts it into two halves ; 

 C, the two halves separate, and each now forms an independent individual 

 (much enlarged). 



In some Monera, especially in the Protamceba (Fig. 163), 

 the formless body, during its movements, invariably de- 

 velops only a few, short, and blunt processes, which project 

 like fingers, slowly altering their form and size, but never 

 branching. In other Monera, on the other hand {e.g., 

 Protomyxa, Myxastrum), very numerous, long, fine, and 

 generally thread-like processes arise from the surface of 

 the movable body, and these branch irregularly, inter- 



