SPEkMATOi.KNESIS OF THE CADDIS-FLY. 6/ 



\oinov i 1 6; has described in the divisions preceding sperm 

 formation in a beetle (Cybister roeselii] a. body which very much 

 resemble- in it- appearance the one under discussion. He, how- 

 ever, <li<l not ob-erve it forming a chromosome tetrad, nor did he 

 follow it during the nuclear divisions except to figure a small 

 darkly -tainin^ body lying outside the nucleu- in the cytoplasm, 

 which he belit -\. - to be the same. It may be that this body 

 niiuht t'r:n a tetr.nl a- in Platyphylax. 



Heidenhuin in "IM.i-ma und Zelle" approves Flemming's opin- 

 ion that the nu< leolu- is always surrounded by a thin Liver of 

 true chromatin. Some appearance such as those shown in Fig. 2 

 would seem to -u^e-t at least that there might be a ring of some 

 other material around the nuclcolus but the structure is so small 

 that it is impossible to say certainly. If this were true, however, 

 tin- ( haiue- de-eribed \\ould only mean that the nucleolus loses 

 ii- loim dining the di\i-ions and becomes pulled out and split, 

 bet \\een iln (hi.. matin -trands surrounding it. 1 



\i an\ rail \\hate\er this structure in Platyphylax may be. 

 wli-ili "accessor} < luomo>ome" or "chromatin nucleolu-." 

 >oun- di-po-itioii o| it iiui-t be made in discussing these aberrant 

 ehn>nio-i mie- in t| lr , lll( | r j <,f insects. 



Thi- \\oi k u as d' me under the direction of Prof. \V. S. Marshall, 

 ot the 1 ni\er~ii\ oi Wisconsin, to whom my thanks are due imt 

 onl\ for assistance with methods and literature but also for quite 

 a portion o| the material from which the sections were made. 



SUMMARY. 



1. The de\elopment of the follicular cysts can be readily fol- 

 lo\\ed in thi- in-ect. Each cyst contains 32 cells derived by 

 5 di\i-ion- tiom a primary spermagonial cell and enclosed in a 

 membrane containing one or two nuclei. 



2. The reduced chromosome number is always 30; the somatic 

 number i- probably 60 from a count in the oogonial divi-ions. 



,v The centro-ome i- onl\ to be followed from the tetrad stage 

 to the anapha-e but probably forms the middle piece of the 

 sperms. 



A CO nu i>t tin- si'iiKiiic nuinlx-r nf chromosomi.-< in the ix'.iKonial division gave 

 5> 60. 1 h- <-\i'i--<linnly lar.m- number makes counting difficult and not very ac- 



i male in tlu-M- ,livi-: 



