THE EVIDENCE OF EVOLUTION. 369 



revealed the weak point in Darwin's conception of the process of 

 evolution. But it was published as part of a larger inquiry in the 

 department of anthropology, and for years and years it has been 

 prominent in that science, without, however, being applied to the 

 corresponding phenomena of the life of animals and of plants. Only 

 of late has it freed itself from its bounds, transgressed the old narrow 

 limits, and displayed its prominent and universal importance as 

 one of the fundamental laws of living nature. 



In doing so, however, it has become the starting point for a critical 

 review of the very basis of Darwin's conception of the part played 

 by natural selection. It at once became clear that the phenomena 

 which are ruled by this law, and which are bound to such narrow 

 limits, can not be a basis for the explanation of the origin of species. 

 It rules quantities and degrees of qualities, but not the qualities 

 themselves. 



Species, however, are not in the main distinguished from their 

 allies by quantities, nor by degrees; the very qualities may differ. 

 The higher animals and plants are not only taller and heavier than 

 their longforgotten unicellular forefathers; they surpass them in 

 large numbers of special characters, which must have been acquired 

 by their ancestors in the lapse of time. How such characters have 

 been brought about is the real question with which the theory of 

 evolution is concerned. Now if they can not be explained by the 

 slow and gradual accumulation of individual variations, evidently 

 the second alternative of Darwin's original proposition remains. 

 This was based on the sports, on those rare and sudden changes 

 which from time to time are seen to occur amongst cultivated plants, 

 and which in these cases give rise to new strains. If such strains 

 can be proved to offer a better analogy to real systematic species, 

 and if the sudden changes can be shown to occur in nature as well 

 as they are known to occur in the cultivated condition, then in truth 

 Darwinism can afford to lose the individual variations as a basis. 

 Then there will be two vast dominions of variability, sharply limited, 

 and sharply contrasted with one another. One of them will be ruled 

 by Quetelet's law of probability, and by the unavoidable and con- 

 tinuous occurrence of reversions. It will reign supreme in the sciences 

 of anthropology and sociology. Outside of these, the other will 

 become a new domain of investigation, and will ask to be designated 

 by a new name. Fortunately, however, a real new designation is 

 not required, since previous to Darwin's writings the same ques- 

 tions were largely discussed, and since in these discussions a distinct 



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