78 LETTER FROM MISS M. E. SMEE. [Feb. 24, 



The following letter, relating to the habits of the Caddis-worm 

 (larva of Phryganea), addressed to Dr. Gray by Miss M. E. Smee, 

 was read to the Meeting : — 



" Feb. 19, 1863. 



" My dear Sir, — I have ventured to send for your inspection a 

 box containing cases made by the Caddis-worm, the worms of which 

 were collected by myself from that part of the Wandle which runs 

 through our garden at Wallington. 



" I found, on examining the natural cases, that they were made of 

 different materials. For instance, some were constructed of small 

 stones finely glued together, others of sticks, and some were formed 

 of sticks and stones combined. Again, some were made of leaves of 

 water-plants, and I observed that others were formed of the shells of 

 creatures which inhabited the same stream. 



" As I had never seen or heard of these Caddises before, I felt 

 much astonished that creatures somewhat resembhng maggots, and 

 living at the bottom of the river, should live in houses built by them- 

 selves, and yet that these houses should diifer so greatly in their con- 

 struction. Indeed I was so interested that I determined, if possible, 

 to discover the capabilities which these creatures possessed of form- 

 ing diiferent kinds of dwellings under different circumstances. I very 

 much desired to know whether they could construct cases from other 

 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- 



