4 THE ENTOMOLOGISTS RECORD. 



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 advantage to 

 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 

 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 m the higher open Arctic plains of 

 Europe, Asia, and America, obscure the sun's rays for the 

 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 

 not here produce melanic forms. 



In a previous paragraph {Entomologisf s Record, etc., vol. i., 

 pp. 8g, 90) 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 

 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, rather than an indirect, cause, we should expect to find 



