MELANISM AND MELANOCHROISM IN BRITISH 
LEPIDOPTERA. 
By J. W. TUTT, F.E.S. 
{Continued from page 325.) 
Tn The Entomologist's Record, etc., vol. i., pp. 232, 233, I 
referred to a paper by Lord Walsingham, in which it was 
suggested that the dark coloration of insects was probably due 
to the rapidity with which these colours absorbed heat in high 
latitudes and altitudes ; and although I quite admitted in my 
remarks, that a dark colour would be an advantage, under such 
conditions, to those insects possessing it, yet, since a dark 
coloration was not characteristic of high latitudes and alti- 
tudes, the advantage due to the rapidity of absorption could 
hardly be looked upon as a cause of melanism. Referring to 
this in his Presidential Address to the Fellows of the Entomo- 
logical Society {vide Trans. Ent. Soc. Loud., i8go, pp. liv., Iv.), 
Lord Walsingham says : — “ Mr. Tutt, referring to a paper of 
my own in which I called attention to the tendency to 
melanism exhibited by Arctic and Alpine Lepidoptera, points 
out that insects from high latitudes are not generally melanic. 
I think I may at once admit that I had used the term ‘ melanic ’ 
somewhat incorrectly in this connection ; what I desired to 
point out was the general tendency of Arctic Lepidoptera to a 
certain suffusion of markings, and to an increase in the pro- 
portion of dull or dingy scales calculated more rapidly to 
absorb heat than the purer white of more southern varieties. 
Such a tendency will, I think, be admitted to exist, but I am 
aware it is far more conspicuous in many insular and Alpine 
districts ; and, while I cannot agree that the arguments put 
forward in that paper are in any way undermined by this 
admission, or that the advantage secured to the species by the 
development of colour capable of rapidly absorbing heat has 
been in any way disproved, I am quite willing to accept Mr. 
Tutt’s assertion that melanism does not habitually occur unless 
lower temperature is accompanied by increased humidity ; 
qualifying the acceptance only by suggesting that anything 
which would have the same effect as increased humidity in 
diminishing the action of sunlight would probably be found to 
produce the same results.” 
I am very pleased that Lord Walsingham thus far admits 
the justice of my criticism. I quite agree with him that the 
