52 THE entomologist's record. 



darker races. The single instance in which the rule holds 

 being the albino in all animals, but this is, after all, a diseased 

 type. If Mr. Birchajl's theory of survival of the fittest be true, 

 and that the darker races in insects, animals, and the superior 

 animal, man, are the fittest, the inevitable conclusion to which 

 it points is, that the darker forms in insect and animal life, and 

 the negro in man, would, after so many ages of ' natural selec- 

 tion,' largely predominate in the world, the contrary being, 

 however, the fact." This is exactly my own position with 

 regard to this subject, and I think that such a theory is alto- 

 gether unsupported and entirely contrary to fact. 



But then Mr. Fetherstonhaugh, to account for melanism, 

 propounds another physiological theory, which is apparently 

 very far-fetched, but which it would be altogether out of 

 reason to assume has no effect. He says: — "Dr. White 

 appears to reject Mr. Birchall's notion that cold, damp 

 climates, with the absence of sunshine, may be the cause of 

 the origin of variations of colour, and suggests meteorological 

 causes."^ He then goes on "May we not then very easily 

 suppose that variations of colour in insects may be, so to 

 speak, accidentally produced by external objects present to their 

 acute vision during the process of generation, and this may 

 occur again and again. It seems to me a less far-fetched 

 theory than to assert dogmatically that dark-coloured insects 

 are endowed with stronger constitutions, and are therefore 

 perpetuated by natural selection." - This suggestion of Mr. 

 Fetherstonhaugh is supported by my friend, Mr. Tugwell, in 

 the Ent. Mo. Mag., pp. 256 and 257, where he writes : — " I 

 am far more inclined to believe in the suggestion of Mr. R. 

 Fetherstonhaugh, that the change is produced by a vivid im- 

 pression of the colour of the surrounding objects on the female 

 insects during the period of generation, and a strong tendency 

 to reproduce in their progeny the same colours among which 

 they themselves have lived ; and, as we know that this 

 phenomenon of nature has been accepted, we may fairly be 

 permitted to consider it as a probable cause of melanism or 

 leucochroism under suitable conditions." Mr. Tugwell then 

 refers to manufacturing districts, London and the New 

 Forest, in illustration of his idea, and gives as examples, — 



' This is hardly my reading of Dr. White's paper. He rejects parts of Mr 

 Birchall's paper, certainly, but can scarcely reject "cold and damp," etc., when he 

 suggests " meteorological causes." 



- It must be noted that Mr. Bircha'll deals with "natural selection " in a physio- 

 logical and constitutional way, Dr. White as selection from protective causes. 



