l8o THE EVOLUTION OF MAN. 



the human organism, is of the simplest conceivable nature. 

 The simplest actually known organisms, and at the same 

 time the simplest conceivable organisms, are the Monera, 

 most of which are minute, microscopic, and formless bodies, 

 consisting of a homogeneous substance, of an albuminous or 

 mucous, soft mass, and which, though they are not com- 

 posed of diverse organs, are yet endowed with all the vital 

 qualities of an organism. They move, feed, and repro- 

 duce themselves by division (Fig. 20). These Monera 



Fro. 20. — A Moneron (Protamceha) in the act of reproduction. A. The 

 whole Moneron, which, like the Amoeba (Fig. 13), moves by means of change- 

 able processes. B. The Moneron is pinched in at a central point, so that it 

 is divided into two halves. C. The two halves have separated and each 

 now forms an independent individual. (Much enlarged.) 



are of great importance, owing to the fact that they 

 afford the surest starting-point for the theory of the origin 

 of life on our earth. We shall presently have further oc- 

 casion to point out their significance. (Cf. Chapter XVI.) 

 Here we need only give due weight to the very remarkable 

 fact that, both in germ-history and in tribal history, the 

 animal organism begins its evolution as a structureless 

 mucous ball. The human organism, like that of the higher 

 animals, exists for a short time in this simplest conceivable 

 form, and its individual evolution commences from this 

 simplest form. The entire human child, with all its great 



