Darwin s Artificial and Natural Selection 107 



to another may be safely attributed to the cumulative action 

 of natural selection, hereafter to be explained, and to the 

 effects of the increased use or disuse of parts. A well- 

 marked variety may therefore be called an incipient species ; 

 but whether this belief is justifiable must be judged by the 

 weight of the various facts and considerations to be given 

 throughout this work." 



In this paragraph attention should be called especially, 

 first, to the statement in respect to the origin of varieties, 

 which are said to arise through individual differences. It 

 is not clear whether these differences are supposed to have 

 appeared first in one, or in a few individuals, or in large 

 numbers at the same time. Again, especial note should 

 be made of the striking admission, that the passage from 

 one stage to another may, in many cases, be the simple 

 result of the nature of the organism and of the physical 

 conditions surrounding it ; but with respect to the more 

 important and adaptive differences, natural selection " may 

 safely " be supposed to have intervened. Is it to be won- 

 dered at that Darwin's critics have sometimes accused him 

 of playing fast and loose with the origin of varieties ? And 

 since this question is fundamental for the theory of natural 

 selection, it is much to be regretted that Darwin leaves the 

 matter in such a hazy condition. It may be said that, at 

 the time when he wrote, he made the best of the evidence 

 in regard to the origin of varieties. Be this as it may, a 

 theory standing on no better foundations than this is not 

 likely to be found satisfactory at the present time. 



We come now to the most important chapters, the third 

 and the fourth, of the " Origin of Species," dealing with " the 

 struggle for existence," " natural selection," or the " survival 

 of the fittest." Behind these fatal phrases, which have become 

 almost household words, lurk many dangers for the unwary. 



" It has been seen in the last chapter that amongst organic 

 beings in a state of nature there is some individual variability : 



