xin VARIATION AND EVOLUTION 133 



John Ray that guiding hand was the superior 

 wisdom of the Creator : for the modern Darwinian 

 it is Natural Selection controlling the direction of 

 variation. Mendelism certainly offers no suggestion 

 of any such controlling force. It interprets the 

 variations of living forms in terms of definite physio- 

 logical factors, and the diversity of animal and plant 

 life is due to the gain or loss of these factors, to the 

 origination of new ones, or to fresh combinations 

 among those already in existence. Nor is there any 

 valid reason against the supposition that even the 

 most remarkable cases of resemblance, such as that 

 of the leaf insect, may have arisen through a process 

 of mutation. Experience with domestic plants and 

 animals shows that the most bizarre forms may arise 

 as sports and perpetuate themselves. Were such 

 forms, arising under natural conditions, to be favoured 

 by natural selection owing to a resemblance to some- 

 thing in their environment we should obtain a striking 

 case of protective adaptation. And here it must not 

 be forgotten that those striking cases to which our 

 attention is generally called are but a very small 

 minority of the existing forms of life. 



For that special group of adaptation phenomena 

 classed under the head of Mimicry, Mendelism seems 

 to offer an interpretation simpler than that at present 

 in vogue. This perhaps may be more clearly ex- 

 pressed by taking a specific case. There is in Africa 

 a genus of Danaine butterflies known as Amauris, 

 and there are reasons for considering that the group 

 to which it belongs possesses properties which render 

 it unpalatable to vertebrate enemies such as birds or 

 monkeys. In the same region is also found the 



