The Caddis-Worm and its Houses. 313 



some experiments with, them, I found that five was about the 

 greatest number I ever obtained from one caddis. The last 

 one was not nearly so strongly or firmly cemented together as 

 the first one. After the fifth one was made, the caddis, when 

 turned out of it, would invariably bury itself under the heap of 

 the materials given to it without even trying to make another 

 case. It seems that the secretion used for cementing the 

 parts together was entirely used up and failed to be further 

 produced. But although five was found to be the greatest 

 number obtained from one caddis, yet it should be stated that 

 if the worms were captured as soon as they were hatched, and 

 experiments tried with them, I believe they would be able to 

 make more than that number. Frequently they did not suc- 

 ceed in making so many as five cases. 



I have seen the small caddises, just hatched, building their 

 tiny houses as early as the beginning of January ; of course 

 being then very little creatures, the materials they are only 

 able to employ must be of the smallest description, like sand, 

 etc., for with larger or heavier materials they would not have 

 the strength to take the particles up with their then tiny feet. 

 As they grow so they must enlarge their houses, always build- 

 ing until the creatures cease to grow larger ; but in what way 

 they expand the circumference of their dwelling I have not 

 been able at present to observe. 



The time taken for a caddis to construct a case varies very 

 much. With some substances a caddis takes more than double 

 the amount of time and labour that it does with others, for 

 with some materials they finish their work in about twenty-four 

 hours, with others again it takes more than a week to do it. It 

 has been already stated, that cases made from broken pieces of 

 glass, jet, shells, or marble, were very much quicker in their 

 construction than when the worms were supplied with either 

 amethyst, or cairngorm, or coral. A shorter time is always 

 taken in the early part of the season, for as the period approaches 

 for the larvas to turn into the pupa state, they require a much 

 longer time to build. 



If it be wished to keep caddis-worms for the purposo 

 of watching these creatures constructing their cases, it will 

 be found to be advisable to let each worm have a separata 

 place to work in. They are so extremely quarrelsome to- 

 wards each other, that if you denude several worms of their 

 houses, and place them together in a vessel of water containing 

 materials for them, you will find that instead of beginning to 

 build they will commence a most deadly warfare with each 

 other, their animosity never being appeased until some ono 

 stronger than the rest succeeds in killing them off. After 

 this the survivor will commence his house as if nothing had 



