272 
DOMICILES. 
Dec., 1892. 
logical Society a long series of similar cocoons; and he 
showed that whenever the larva was left undisturbed and 
was allowed to crawl into white surroundings the cocoon was 
of the normal brown colour ; but wherever the caterpillar had 
been taken away, vi et arm,is, from his leaves, and put into 
another place—whether white or dark—he spun a light- 
coloured cocoon. This put a wholly new face on the matter ; 
it indicated that the light colour was due not to the surround¬ 
ings, but to the disturbance. The dark colour is apparently 
a secretion; and when the animal is vexed or out of 
condition—and nothing so much alarms him as being 
pulled about when he is going to change—he loses the power 
of secreting this colour, and spins white. This rebuff set 
Mr. Poulton experimenting again with another beast—namely, 
this very Green Silver Lines—and he tells me that he has 
again succeeded in getting white cocoons in white surroundings 
from undisturbed larvae ; nay, in the very same glass case, 
those larvae which spun among the white were white in their 
silk, and those which spun among leaves or in the open were 
of the usual dark colour. There at present the matter rests ; 
and a very pretty quarrel it is, and very illustrative on all 
sides of the methods and the difficulties of scientific research, 
and the stages of its progress. If the results so far reached 
are confirmed—and very wide and careful experiments are 
needed to make the ground sure—the outcome will be 
this: that some species have, and others have not, the 
remarkable power of accommodating the colour of their 
cocoons to their surroundings ; and it will be needful to try a 
great variety of species on a large scale to find out in what 
the difference lies. 
To return to our domiciles. Nothing is more remarkable 
in the domiciles of the pupae than the great difference in the 
apparent comparative security of the pupa-cases even of allied 
species. Let me take a case of a safe and an unsafe one for the 
sake of contrast. Perhaps the safest of the commoner kinds 
is that of the Puss-moth. The specimen I show is unfor¬ 
tunately not made under natural conditions, as there are no 
chip-boxes to be found concealed in the roots of willow trees. 
But even from the specimen I show can be seen the extremely 
business-like character of the structure. It is made of bits 
of wood, carefully gnawed, and fastened together by a 
natural glue which the creature exudes for the purpose, and 
which dries very quickly into one of the hardest cements one 
can imagine. In nature the spot selected for dwelling is 
some recess between two prominences of the bark, and the 
outside being covered by the outside bits of the bark, and, 
