-I'KKMATOoENESIS OF THE CADDIS-FLY. 59 



In all of the species so far described, however, the cysts lie 

 so clo-i -ly appre--ed against each other and against the follicu- 

 lar wall that ii i- impossible to decide certainly as to the identity 

 of ill.- cyst \\.ills. In all of them too the number of cells seem- 

 to In- lar^e. In the-e n --peels Platyphylax offers a much better 

 opportunity for deriding the question of cyst wall and cell num- 

 l"-r in a cy-t . 



Tlu t-.irli. of the reproductive organ that I wa- able 



to 1,..- -UK- \\ ,i~ tin- testes \vas that shown in Fig. I . At this stage 

 then- ha- already appeared the lobing into five divi-ion- that i- 

 so characteristic of tin- mature organ. The cells compo-ing it 

 are apparently .ill ot "about the same size; there being at this time 

 no \ i-ible dill- nil t ia' ion into germ-cells and cyst epithelial rell-, 

 it -IK Ii d<- i. I In- nuclei of these cells are a little la: 



than iho-e in other part- of the body. The distribution of 

 chromaiin in the-e nm lei i- characteristic of that in all parts of 

 the bod\ , the piece- l>ein;< of rather large size and ot a rather 

 regular number iii-tead o| having the form of tine granule-. 

 Sometime- these pii : chromatin are in the form of bodie- 



uhich miijit \\ell be taken for split chromosomes, while other- 

 ha\e the diamond -hape characteristic of the tetrads with \\hich 

 the\ might leatliK be i . .niounded ( Fig. 3). Divisions are rather 

 ran at tin- linn- and ^louih is apparently rather slow. The 

 di\i-ion ti^iuv- ob-ei \ ed \\ere of typical initotic type. The 

 pei uliar p. irt that the nm leolus plays in thi- division \\ill be 

 di-cu cd under the reduction divisions as in them it is much 



ger and UK ni le.idiK followed. All that i- nece-sary to say 

 hen- i- that it -i em- to change its spherical -hape, bet . mie- 

 elon-.ii,-d and a|>]>an-nil\ lorni- a chromosome. 



In the testes next adxanced in the stage of development the 

 |irimar\ -]n-i in.i-onial ci-lls occup>" onl\ about a third of the S] 

 while the remainder of ii i- Tilled with the secondary -pernia- 

 gonial cells in various s >f di\ ision to form the mature c\ sts 



call be lolloued .it e\ el \ 



The testes ha\e ;^roun cmi-iderably. The !i\e tli\ i-ions are 

 fully formed: the\ ha\e aci|iiired distinct cellular boundaries; 

 and the original -ecoiidar\ -permagonial cells, instead of being 

 rather C!OM-|\ packed iu the te-tes, are now lying with consider- 



