4 
THE ENTOMOLOGISTS JlECOllD. 
arguments in his “ paper are in no way undermined ” by his 
admissions, except so far as these arguments seek to bear out ; 
that dark coloration, owing to the rapidity of heat absorption 
is a cause of melanism ; the arguments brought forward to ' 
show that dark coloration is in certain cases an adva^itage to I 
the insects possessing it are certainly as potent as ever. I do 
not, however, altogether agree with his suggestion “ that any- 
thing which would have the same effect as increased humidity 
in diminishing the action of sunlight would probably be found I 
to produce the same results,” unless indeed, it would have the 
same effect in influencing the surroundings, and thus promote \ 
the same course of development by “ natural selection.” For 
example, snow-clouds in the higher open Arctic plains of ^ 
Europe, Asia, and America, obscure the sun’s rays for the j 
greater part of the year, for a much longer period of time 
certainly than do the rain-clouds, etc., of our own Islands ; , 
again. Nature shuts out the light of the sun from the greater 
part of these areas, with the exception of a very few hours, 
for the whole period from November to February, and yet the ' 
insects from these open Arctic plains show no tendency to 
melanism, as I have over and over again repeated, when ' 
attempting to show that cold in these regions does not produce 
melanic forms. Here we have insects brought up naturally ' 
with a minimum of sunlight affecting them, but Nature does j 
not here produce melanic forms. 
In a previous paragraph {Entomologisf s Record^ etc., vol. i., 
pp. 8g, go) I stated that I failed to see how the absence of 
sunlight could in any way account for any form of melanism 
or melanochroism in lepidoptera, but Lord Walsingham, as 
may be gathered from the preceding paragraph, appears to 
think differently, and opens up a new path in this direction. 
He says : — “There are many local circumstances which cause 
an interference with direct sunshine ; dense forests occur ' 
where the full rays of the sun never penetrate, clouds and 
mist accumulate around the summits of high mountains, fog j 
and smoke envelop the districts immediately surrounding our 
manufacturing towns, islands in a temperate climate are sub- 
ject to condensation of moisture and sea-fogs, and under all ^ 
these circumstances dark varieties of certain species are known ; 
to occur, although the same species when found under different 
conditions more favourable to the action of light, are usually 
less intensely coloured. But if moisture is to be taken as a 
direct, rg.ther than an indirect, cause, we should expect to find 
Bll 
