duced beneficial results, in uncritical lay-circles this ferment 

 produced nothing but a corruption of world-views. 



Hertwig then designates "Struggle for Existence," 

 Survival of the Fittest, and Selection, as "very indefinite 

 expressions." "With too general terms, one does not explain 

 the individual case or produces only the appearance of an 

 explanation whereas in every case the true causative rela- 

 tions remain in the dark. But it is the duty of scientific 

 investigation to establish for each observed effect the pre- 

 venient cause, or more correctly, since nothing results from 

 a single cause, to discover the various causes." 



"The origin of the world of organisms from natural 

 causes, however, is certainly an unusually complicated and 

 difficult problem. It is just as little capable of being solved 

 by a single magic formula as every disease is of yielding to 

 a panacea. By the very act of proclaiming the omnipotence 

 of natural selection, Weismann found he was forced to the 

 admission that: "as a rule we cannot furnish the proof that 

 a definite adaptation has originated through natural selec- 

 tion," in other words: We know nothing in reality of the 

 complexity of causes which has produced the given phe- 

 nomenon. So we may on the contrary, with Spencer, 

 speak of the "Impotence of Natural Selection." 



"In this scientific struggle with which the past century 

 closed, it seems necessary to distinguish between the doc- 

 trine of evolution and the theory of selection. They are 

 based on entirely different principles. For with Huxley we 

 can say: "Even if the Darwinian hypothesis were blown 

 away, the doctrine of Evolution would remain standing 



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