310 The Caddis-Worm and its Houses. 



Another material capable of being made into a caddis case 

 is coralline. This substance forms a very curious dwelling. 

 I had some constructed from pieces of a kind of coralline 

 when dead, or rather when only the skeleton remained of it. 

 These pieces of this dead or skeleton coralline are blanched, 

 and are put together in such a manner that the case has an 

 appearance as if it had been the work of a basket maker, 

 instead of that of a larva. 



But perhaps a more singular-looking case than even these 

 wicker-work ones are those which are made from pieces of 

 tortoiseshell, such as fragments of the teeth of a tortoiseshell 

 comb. If these be given to a worm, it will be seen that it will 

 arrange them crossways. In doing so it will make its house 

 slightly resemble a hedgehog whose bristles are erected. It 

 seems astonishing that there is such a variety of form in the 

 appearances of these different caddis cases. For what can be 

 more unlike each other than cases made from fragments of the 

 teeth of a comb, and that from the pieces of skeleton coralline ? 

 What also is more extraordinary, is, that the same worm which 

 can build the basket-looking case can also construct the one 

 resembling a hedgehog when its bristles are erected. In fact, 

 if a caddis is able to make itself a case from any one of the 

 substances already mentioned, it is able to build from all of 

 them. For I have tried their capabilities in that way by 

 giving a caddis a certain kind of material to construct its 

 house, and as soon as it was completed I turned it out, and 

 then give the same worm something different to work upon. 



With these new materials it would commence building 

 with as much ease as it did with the former materials, although 

 consisting of a totally different kind of substance from that 

 which it employed in the formation of its previous case. 



Although these caddises are so wonderful in being capable 

 of forming cases for themselves of such a variety of structure, 

 yet it is not every substance that bhey are able to employ for 

 building materials. They are incapable of using anything 

 when existing in a certain form. For instance, although glass 

 is an easy kind of material for a caddis to work with, yet if 

 tin- form and surface of that glass bo smooth and round, as in 

 a small bead, tin: caddis will be totally unable to make a case 

 from it. In broken glass the pieces are always somewhat 

 angular, and present no difficulty to tho worm. Generally, I 

 may state that not only round heads, but eveiy object which is 

 rounded in form and smooth in surface, is unfit for building 

 material, whilst substances with angles and curves are quite fit 

 for the ase of a caddis-worm. There are some substances that 

 exhale certain odours, which render them also quite unfit to be 

 used. These scented materials arc so highly noxious to the 



