1863.] LETTER FROM MISS M. E, SMEE. 79 



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, 1 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- 

 ing 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 

 feet, turning it on all sides to discover whether it will fit into the 

 space, and if it does not, as is frequently the case, that piece of stone 

 is instantly rejected, and another is tried after the same manner, until 

 they succeed in finding a suitable piece, when it is cemented to the other 

 stones by a secretion which I ascertained proceeded from their mouth. 



" When their house is made, the body of the creature is completely 

 encased ; their heads and feet alone protruded. 



" In their natural state, the weight of these cases varies much. 

 They are twice as heavy, and made of more solid materials, when the 

 creatures inhabit rapid streams than when they live in still waters. 

 The reason of this difference is, I suppose, to enable themselves to 

 keep, by the weight of their cases, at the bottom of the water. 



" I noticed that, after the Caddis-worms were turned out of their 

 cases, air-bubbles appeared on the surface of their bodies. If placed 

 under these circumstances in running water, these air-bubbles would 

 cause the creatures to rise to the surface and there float until they 

 died from exhaustion, caused by their hard endeavours to reach the 

 bottom. According to the roughness of the water, so must be the 

 weight of their cases. 



" When in the pupa-state, their heads and feet are entirely with- 

 drawn into their cases ; and they remain in a dormant state, neither 

 eating nor moving, until they turn into flies, their cases being more 

 or less split in the act of transformation. 



" I used to feed some of my Caddises whilst in the larva state with 

 small pieces of raw meat, which they ravenously devoured; they would 

 even eat a common house-fly, leaving only the wings, head, and leg ; 

 but however hungry they might be, yet they never could be induced 

 to touch cooked meat. 



