442 NATURAL SCIENCE. Jong, 
cons ders (Tvans. Ent. Soc. Lond., 1892, pt. iv.) this species to be 
less susceptible than other Catocalide. 
Catocala fraxint certainly showed a distinct difference, not only 
of shade, but of colour, larvae reared in green surroundings being 
distinctly greenish in hue, while those in dark were brownish. Mr. 
Poulton obtained only a difference in shade, otherwise his results 
were similar. 
With Mamestra brassice | had negative results ; the larve were not 
affected at all by surroundings, and I believe this unsusceptibility to be 
due to the burying habits of this species, which render colour of 
secondary importance to the larva. Mr. Poulton’s results differed a 
little from mine, but he thought that his larve were not in sucha 
healthy condition as mine, which might account for this. There are, 
however, special difficulties in investigating M. brassice, and Mr. 
Poulton considers the experiment worth repeating. 
Since publishing these results, I made some experiments, at Mr. 
Poulton’s suggestion, on larve of Triphena pronuba, which I was rearing 
for him for other purposes. I had 59 larve in different surroundings, 
and as this species, like M. brassice, buries by day, I used different- 
coloured materials on the floor of the cylinder, such as white sand, 
yellow gravel, pounded red flower-pot, and, in one case, small coal. 
The larve buried in all these, except in the coal, which they evidently 
disliked, but the results were, as in M. brassice, negative, with two 
possible exceptions from green surroundings, without any burying 
materials; these were, however, not very definite. The burying 
materials were in all cases used in addition to sticks of the suitable 
colour mixed with the food-plant. 
Besides the foregoing experiments, I also made some notes on 
the red spots in Smerimthus larve, from larve of S. tilig sent me by 
Mr. Perkins at Mr. Poulton’s request. These larve were all from 
parents which had been spotted in the larval stage. Unfortunately, 
many were injured by their transit by post, and I only succeeded in 
rearing four, which were all spotted. I also captured a larva of 
S. popult in which the spots were extremely well marked. The spots 
were certainly protective in effect, on account of their resem- 
blance to the dark spots or blotches common on leaves of poplar, 
and this fact was long ago pointed out by Mr. Peter Cameron 
(Tvans. Ent. Soc. Lond., 1880); but although he considered the like- 
ness to galls (Phytoptus) very striking, it seems to me, in S. populi at 
any rate, far greater to flat spots on the leaf seen with the light shining 
through them. 
In S. tlie I studied the development of the spots very carefully, 
and in one individual I found them very linear and strongly sugges- 
tive of coloured borders; in the others they were much bolder and 
rounder, and presented quite a different appearance. Professor 
Weismann, as is well-known, considers the spots as on the way to 
develop into borders, while Mr. Poulton takes the view that we 
