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believe that animals are descended from at most 

 only four or five progenitors, and plants from 

 an equal or less number." Monophyletic evo 

 lution, even in the sense ''that all the organic 

 beings which have ever lived on this earth may 

 be descended from one primordial form," he 

 regarded as neither impossible nor incredible, 

 but the only evidence in its favor was, he be 

 lieved, "chiefly grounded on analogy." In any 

 case, he regarded it as wholly "immaterial" to 

 the theory of evolution "whether or not it be 

 accepted." (3) On the importance of "natural 

 selection" as a factor of evolution there is a 

 slight difference between Darwin and Father 

 Wasmann ; but only slight. Darwin regarded 

 natural selection as the chief, "but not the ex 

 clusive means of modification." He admitted 

 "the inherited effects of use and disuse," "the 

 direct action of external conditions," and also 

 the influence of "variations which seem to us 

 in our ignorance to rise spontaneously." Fa 

 ther Wasmann, while apparently making light 

 of natural selection, and while proclaiming 

 it to be a merely "subsidiary factor," never 

 theless tells us "it is indispensable" as such 



