MARXISM AND DARWINISM. 11 



kind to another take place before our eyes, so that 

 we could observe it. But this is impossible. How 

 then is it at all possible to prove that animal forms 

 are rea41y changing into new forms? This can be done 

 by showing the cause, the propelling force of such de- 

 velopment. This Darwin did. Darwin discovered the 

 mechanism of animal development, and in doing so 

 he showed that under certain conditions some animal- 

 kinds will necessarily develop into other animal-kinds. 

 We will now make clear this mechanism. 



Its main foundation is the nature of transmission, 

 the fact that parents transmit their peculiarities to 

 children, but that at the same time the children diverge 

 from their parents in some respects and also differ 

 from each other. It is for this reason that animals 

 of the same kind are not all alike, but differ in all 

 directions from the average type. Without this so- 

 called variation it would be wholly impossible for one 

 animal species to develop into another. All that is 

 necessary for the formation of a new species is that 

 the divergence from the central type become greater 

 and that it goes on in the same direction until this 

 divergence has become so great that the new animal 

 no longer resembles the one from which it descended. 

 But where is that force that could call forth the ever 

 growing variation in the same direction? 



Lamarck declared that this was owing to the usage 

 and much exercise of certain organs; that, owing to 

 the continuous exercise of certain organs, these be- 

 come ever more perfected. Just as the muscles of 

 men's legs get strong from running much, in the same 

 way the lion acquired its powerful paws and the hare 

 its speedy legs. In the same way the giraffes got their 

 long necks because in order to reach the tree leaves, 



