PRESENT STATUS OF THE QUESTION 19 



of chance, but those individuals persist which are 

 the most vigorous and any variation from the average 

 of the species which confers an advantage in the 

 struggle will tend to be preserved and to increase 

 in successive generations. Darwin, as he tells us, 

 very early perceived that in making new breeds of 

 domesticated animals and plants, selection of the 

 parents according to the characteristics which it was 

 desired to perpetuate and improve, played the im- 

 portant role and he concluded that advantageous 

 variations, by enabling their possessors to survive 

 in the struggle, would furnish the material for the 

 formation of new species, while any disadvantageous 

 variation would be promptly extinguished. 



(4) Finally, there is the fact of heredity. It is a 

 commonplace that individuals are like their parents 

 and should the parents have from birth some ad- 

 vantageous peculiarity, this would tend to reappear 

 in the offspring. A repetition of this process from 

 generation to generation would have a cumulative 

 effect, resulting in very extensive changes. 



While Darwin always maintained that natural 

 selection was by far the most important and effi- 

 cient cause in producing transmutation, he admitted 

 the action of other, though minor factors. Thus, 

 he makes frequent appeal to the effects of use and 

 disuse of organs, the agency which Lamarck had 

 regarded as of such primary importance, and he 

 advanced the theory of sexual selection to account 

 for the brilliant colouring and elaborate patterns 



