Characters, Hereditary and Acquired. 51 



would there be an incalculable waste, so to speak, of 

 adaptive modifications— these being all laboriously 

 and often most delicately built up during life-times of 

 individuals only to be thrown down again as regards 

 the interest of species— but so large an additional 

 burden would be thrown upon the shoulders of natural 

 selection that it becomes difficult to conceive how 

 even this gigantic principle could sustain it, as I shall 

 endeavour to show more fully in future chapters. On 

 the other hand, however, Weismann and his followers 

 not only feel no difficulty in throwing overboard all 

 this ready-made machinery for turning out adaptive 

 modifications when and as required ; but they even 

 represent that by so doing they are following the 

 logical maxim, Entia non sunt multiplicanda praeter 

 necessitatem — which means, in its relation to causality, 

 that we must not needlessly multiply hypothetical 

 principles to explain given results. But when appeal 

 is here made to this logical principle — the so-called 

 Law of Parsimony — two things are forgotten. 



In the first place, it is forgotten that the very 

 question in debate is whether causes of the Lamarck- 

 ian order are unnecessary to explain all the phe- 

 nomena of organic nature. Of course if it could be 

 proved that the theory of natural selection alone 

 is competent to explain all these phenomena, appeal 

 to the logical principle in question would be justi- 

 fiable. But this is precisely the point which the 

 followers of Darwin refuse to accept ; and so long as 

 it remains the very point at issue, it is a mere begging 

 the question to represent that a class of causes which 

 have hitherto been regarded as necessary are, in 

 fact, unnecessary. Or, in other words, when Darwin 



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