252 THE ENTOMOLOGIST. 
“As is well known, Chelonia caja is one of the most 
variable of species. Variation amongst insects is a question 
not less interesting than evolution, and by what circum- 
stances it is produced has not yet been satisfactorily ascer- 
tained. Without pretending to have solved the problem, I 
will briefly relate the result of some experiments I have 
made with this species, of which I have had sia thousand 
under my care. I had an idea, in common with other ento- 
mologists, that the food of the larva might influence the 
colour of the perfect insect. 1 therefore made separate trials 
with walnut, horse-chestnut, sumach, box, celandine, carrot, 
and lettuce; and some I have reared in complete darkness. 
It will be easily understood why I chose food so diverse. 
With the walnut, chestnut, and sumach,—trees having a 
bitter-sweet flavour,—I hoped to produce melanite varieties ; 
with the box, carrot and celandine, yellow varieties; with 
the lettuce, light varieties; and from those kept in total 
darkness I hoped to obtain complete albinism. 
“ These, however, are the results of my experiments :—The 
walnut, chestnut and sumach killed many larve; a few, 
however, reached the perfect state, but they were mis-shapen, 
half-abortive and crippled; in fact, only worthy of figuring 
in a museum of curiosities. The box was eaten for a few 
days, but the larve would then eat no more; and as I did 
not change the food they all died of starvation. The 
celandine was eaten greedily; the greater part of the larve 
formed chrysalids, but all perished in the cocoon except one, 
which not having sufficient strength to develop emerged a 
cripple, without indicating any kind of variety. As for the 
carrot, | found nothing worthy of recording. The lettuce 
only produced pale, dull, discoloured specimens. Those 
brought up in total darkness all perished in the third change. 
Such is the account of my experience: food-plants so diverse 
as to give fair expectation of good varieties produced none 
worth record. The few varieties which are in my cabinet 
were all from larve bred on the usual food-plants, riz. 
dandelion, chickweed, dock, groundsel, plantain, &c. I have, 
however, remarked that it was always during s/orms, when 
the air was charged with electricity, that the varieties 
emerged. Is it possible that electricity is a chief agent in the 
variation of Lepidoptera ?” 
