o 'y 
NATURE NOTE'S 
After this the sand was forsaken for building purposes, except 
in four solitary cases. Of these one caddis was particularly 
conservative and kept to the sand ; two built the under part of 
sand, and that part which covered the back of mother-of-pearl ; 
and another ignored both sand and pearl, and, using bits of 
waterweed, appeared as a veritable “Jack in the Green.” 
At first the cases were so transparent that the waving motion 
of the body within could be quite clearly discerned. Later the 
movement was more obscured, and at last entirely hidden, 
perhaps by the thickness of the gluten and silk with which each 
case was lined. 
In the early morning the sand at the bottom of the aquarium 
was etched with a maze of lines caused by the caddises walking 
round and round and dragging their castles after them. Up to 
mid-day they seemed to do nothing but perambulate the sand 
in a ridiculously serious manner, except occasionally one would 
halt, forage in the sand for a second or two, and then pass on. 
Assiduously as we watched the little creatures, we were never 
once fortunate enough to see them in the act of cementing fresh 
bricks to their castles. This was evidently the work of the 
night, for in the morning we were often able to detect where 
new material had been added to several of the cases. 
Of all the myriads which swarmed in the water in the early 
stages, only about two dozen arrived at maturity ; but this was 
an advantage, in that it enabled us to single out individuals and 
upon them concentrate our observations. 
Their feeding-time they altered once or twice during their 
short existence, but it was generally about mid-day that, as 
though with one consent, they scrambled up among the weed 
and began to feed. They had splendid appetites, and con- 
stantly required fresh supplies of food. Of watercress they 
were particularly fond. Some would get to the edge of the leaf 
and gnaw from left to right, others from right to left, and others, 
again, would strip the leaf of its fleshy surface and leave behind 
patches of thin transparent tissue. 
The shape of the castles was that of the elephant-tooth shell. 
The wide end, from which the head protruded, was not a com- 
plete circle, as one sees represented in books (although this was 
the form after the perfect insect had emerged), but was hooded 
over at the back to protect the head when feeding, and hollowed 
out in the front to allow room for the play of the neck. 
On January 28 we thought we would tempt them with a 
brighter building-material, and added some crushed glass of a 
brilliant green. Several times we saw them foraging amongst 
this new material, but not one single fragment did they utilise. 
At times one or other would hang up his castle on a piece of 
weed and retire into its depths for a prolonged fast of two days, 
after which he would reappear and feed more voraciously than 
ever. 
The head was noticeably paler in colour after the fast, and 
