400 Zoological Society . — 



kinds of materials, besides those usually existing in the river in which 

 they lived. 



" To ascertain the fact, I accordingly turned the worms out of their 

 natural cases, and gave them different substances to work upon ; but 

 I found that they had not an equal facility with every material ; for 

 whilst with some they formed cases which were attended with good 

 results, with others they entirely failed. 



" The worms succeeded well when they were supplied with pieces 

 of glass, amethyst, cairngorm, cornelian, onyx, agate, coral, coralline, 

 marble, shells, jet, brass shavings, gold-leaf, silver-leaf, when existing 

 as small fragments. 



" "When, however, the worms were supplied with round objects, 

 they invariably failed ; and although I have repeatedly tried them 

 with small glass beads and other round objects, I never found that 

 with these they were capable of forming a case. 



" But these Caddises also failed to make themselves houses from 

 other causes than that of the roundness of an object ; for I found that 

 if these creatures were placed among materials strongly scented, or 

 which contained poisonous matter, not only were they unable to 

 build with them, but in most cases the substances proved fatal to the 

 worms. When I tried them with pine-wood, my Caddises would in 

 a short time become completely stupified from the turpentine con- 

 tained in the wood, from which they often never recovered. With 

 pieces of coal, brick, or slate they never succeeded in making a 

 case, although these substances did not cause their death. The rea- 

 son for their failure I attributed to some kind of odour which might 

 have emanated from these different materials. With painted or var- 

 nished objects they also failed. Not every kind of metal was suit- 

 able for their buildings ; for neither with tin, or lead, or copper did 

 they succeed. I found that if one Caddis was not able to make a 

 case out of any one kind of material, no other Caddis could succeed, 

 although I might try several others with the same material. 



" After a Caddis had made two or three houses, I used to give it 

 something fresh to work upon, and oftentimes I supplied it with a 

 totally different material. With these new substances it proceeded 

 to build as quickly as before, constructing its new habitation accord- 

 ng to the shapes of the pieces it had then to deal with. 



" The maximum amount of artificial cases I could get any Caddis- 

 worm to make was five, the last one being very brittle, the parts being 

 scarcely glued together. After they had built so many houses, if 

 turned out of the last house, they would simply bury themselves and 

 remain in a quiescent state. But I think that if the Caddises were 

 procured early in the year, the number of their cases might be con- 

 siderably increased. 



" It is a most curious sight to see these little creatures building 

 their houses, beginning by cementing a number of pieces loosely to- 

 gether. This is merely used as a foundation for building its subse- 

 quent structure ; for it is always cast off before the house is completed. 

 After they have laid the foundation, they proceed by lifting up each 

 piece of stone, or whatever the material may consist of, with their 



