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. Birchall’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. Birchall deals with “natural selection ” in a physio- 
logical and constitutional way, Dr. White as selection from protective causes. 
