56 B. F. LUTMAN. 



complex of spermatozoa takes on the form of a long-drawn out 

 cylinder. The nuclei are all arranged at one end, pointing one 

 way, while the body of the sperm fills the remaining space. 

 These he calls spermatocysts. 



The formation of the free spermatozoids does not seem to 

 occur either in the free or the enclosed larvae. At the time of 

 pupation there are only spermatocysts. In the pupa there re- 

 sults along with growth and the further differentiation of the 

 spermatozoids the resorption of the walls of the spermatocysts. 

 In the mature pupa the spermatozoa are free and lie in thick 

 knots in each division of the testes. 



The caddis-flies, as has long been known, pass practically their 

 entire life in the larval and pupal stage. Vorheis (17), who has 

 followed the life-history of Platyphylax designatus, has found that 

 the eggs are laid in April and that the larvae appear about two 

 \veeks later. During summer and fall the larvae grow, and from 

 November to January more and more larvae are found. The 

 period of pupation begins about the middle of February and is 

 indicated by larger irregular stones being attached to the anterior 

 end of the sand cases "while some are attached to the lower sur- 

 face of the large rocks by a mass of silk at the anterior end." 

 For a few days after the closing of the case the larvae remain 

 inactive but unchanged, before becoming pupae. 



The caddis-fly larvae offer the advantage that while the life- 

 history just sketched is gone through with at about the time 

 indicated, larvae of almost any size may be still obtained up until 

 January and February. The material was obtained during three 

 years; the first year from about the first of December to the first 

 of February; the second year during the month of June, and the 

 third year in May. The spermagonial and reduction division 

 occur in the larval stage, so the half-grown larva- of a length of 

 6-lo mm. was the material in which it was found. The sperms 

 are apparently all formed at or soon after pupation. 



In the older specimens the testes were dissected out, but in 

 order to get the very young spermagonia it was nere>.-ary to 

 section the entire abdomen. 



Practically all the material was fixed in Fleming's weaker 

 solution although sublimate-acetic was used on some abdomens 



