THE SI'KKMATOGENESIS OF THE CADDIS FLY 

 I'l.ATYPHYLAX DESIGXATUS WALKER). 



B. F. LUTMAX. 



The numeroii- w< >rk- that have appeared in recent yours on 

 the -pern nesis <>f insects have covered practically every 



order .ind in ~<mir order-, such as the Hemiptera, main of the 

 import. mi l.iinilic-. There still remain, however, a number of 

 the -in. ill T order- \\liirh have not been investigated, and there 

 i- ,il\\ a> - the po^jl.jljty th.u these may contain new or especially 

 l"a\orable structures. The Trichoptera is one of tlu--e -mall 

 orders. The \eun>ptera and Lepidoptera to which it i- belie\ ed 

 to be nio-i iiearK related haxebeen investigated by Miss Mi < ".ill 

 ind l\ 'l"o\ama i > .in. ! II' nking (2). The small size of the 



lar\a- and the diltu ill' ; i--ecting out the very youni; tests 



ha- ptobabh deterred in\ e-i uators from attacking thi- ^roup 

 \\hen larger, belter kiioun and more easily ol)tainable form-urn- 

 to be had iii the Hi inipieia and Orthoptera. 



I -hall HOI gO ilU" all extensive discussion here of tile general 



liieiature "I -perma t o^me-i-. Phityphylax has in the main the 

 -aim- de\ e|.i|unein that ha- been described for all insect lorm-. 

 There are certain points in which it is different and the literature 

 on them uill be di-cu--ed in connection \\iih my own ob-er\a- 

 t ii Hi-. 



The onl\ p.iper iii \\hich the spermatogenesis of the Trichop- 

 tera i- di-cu ed .ii .ill i- in that of Lubben (3). Lubbc-n \\a- 

 moie init re-ied in the external morphology and the development 



of tin- te-le- than he \\a- ill the CVtological details, but heob-er\ed 

 a number of f.ut- \\ell \\orth noticini;. The sperm. i^onial cells 

 ari-e dit of the original genital cells by division. They K r " w 

 into l.ir-e cell- \\ hich appear, united with two cy-t epitheli.il cell-. 

 The origin of the-e epiihelial cells of the cysi- \\as not clear to 

 him. In-ide the-e epithelial cells now ari~e- a mass of cells by 

 divi-ion. Then b\ two more division- the spermutids ure pro- 

 duced; the-e ha\e -harply bounded nuclei \\ith cli-ar pla-ma 

 around them. The -|ierm.itid- iiuTea-e in length and the whole 



55 



