WM THE NEW EVOLUTION ®® 



composed of a single cell represent the primitive animals from 

 which all others are derived. They are commonly supposed to 

 have preceded all other animal types in their appearance. There 

 is not the slightest basis for this assumption beyond the circum- 

 stance that in arithmetic — which is not zoology — the number one 

 precedes the other numbers. 



Arithmetical simplicity in the broader features of animal struc- 

 ture does not by any means imply biological simplicity of func- 

 tions and of reactions. In the animals with bodies composed of 

 a single cell that single cell is so excessively complex in its physi- 

 cal and chemical makeup that it is able to perform of itself alone 

 all of the vital and mechanical functions which in other creatures 

 are distributed among a greater or lesser number of special organs, 

 each of which is composed of more or less numerous cells fitted to 

 perform a more or less limited range of functions. 



Two animals each able with equal success to carry on all of the 

 very numerous and complicated functions necessary for animal 

 existence, and at the same time equally efficient in meeting the 

 limitations and restrictions imposed by external forces, would 

 seem to be on quite the same footing, and therefore of an equal 

 degree of specialization. If this were not so — if on the other 

 hand the arithmetically simpler creatures were biologically more 

 simple than the arithmetically more complex — can anyone give 

 any good reason why the former should not have disappeared as 

 the latter appeared? 



No reason can be given. All of the different major groups of 

 animals existing at the present time are, in their respective spheres 

 of action, equally efficient. If they were not, the more efficient 

 would soon exterminate the less efficient. Among the various 

 major groups of animals as we find them at the present day there 

 is no possible question of simplicity or of complexity, of primi- 

 tiveness or of specialization, from the strictly biological stand- 

 point. 



In size, and in everything correlated with size, the fish or the 

 crustacean is vastly superior to the protozoan. In number of 

 individuals, potentiality for rapid increase, and ability to survive 

 adverse conditions, the protozoan is vastly superior to the crusta- 

 cean or the fish. While so far as the existence of the individuals 

 is concerned, the fish and the crustacean, because of their size, 

 power, locomotor ability, and capacity for offense and defense, 



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