EXPLANATION OF PLATES, III— IV. 



All figures are drawn with Abbe's camera lucida as well as drawing prism. 



Objectives and oculars used, are mentioned with explantions of figures. 



Fig. i. Surface view of male sexual organ of larva two days old. Killed with 

 picro-acetic acid and stained with alcohol carmine, (t) testis, (d) dorsal 

 vessel. (Zeiss, Obj. D, Oc. I). 



Fig. 2. Surface view of female sexual organ of larva two days old. Similarly 

 treated as above, (o) ovary, (d) dorsal vessel. (Zeiss, Obj. D, Oc. I). 



Fig. 3. Terminal portion of vas deferens of larva in fifth stage, (;») muscle, (c) 

 uterus-shaped process of ventral median side of twelfth segment. Treated 

 as above. (Leitz, Obj. 1, Oc. 4). 



Fig. 4. Longitudinal section of testis of embryo, about two days before hatching. 



It will be seen that here testis consists of single cavity with round genital 

 cells and " Hodenzwischenkorperchen " (/;) scattered in it. Killed with 

 i c / a formic acid and stained with borax carmine. (Zeiss, Obj. J, Oc. 3). 



Fig. 5. Longitudinal section of testis of larva just hatched. (/) first three de- 

 pressions on follicular wall ; (;') second four invaginations. Killed with 

 Flemming's stronger solution and stained with Hermann's triple staining. 

 (Leitz, homog. imm. 1/12, Oc. 3). 



Fig. 6. Longitudinal section of testicular follicle, of larva three days old, with 

 invaginated follicular wall and supporting cell (v) (Verson's cell). Treated 

 as above. (Leitz, homog. imm. T / l2 , Oc. 2). 



Fig. 7. Longitudinal section of testicular follicle of larva, one day after fourth 

 moult : left side of figure represents formative zone and right side is 

 place where vas deferens takes its origin, (v) Verson's cell ; (h) " Hoden- 

 zwischenkorperchen." Treated as above. (Zeiss, Obj. BB, Oc. 4). 



Fig. 8. Blind end of testicular follicle, showing protoplasmic strand (p) connecting 

 Verson's cell with follicular wall. Killed with Rabl's platinum chloride 

 and stained with Bohmer's hematoxylin. (Zeiss, Obj. D, Oc 4). 



Fig. 9. Verson's cell, with small degenerating cells surrounding it; taken from 

 larva within coccoon. Killed with Flemming's stronger solution and 

 stained with acid fuchsin. (Leitz, Obj. 7, Oc. 4). 



Fig. 10. Small portion of testicular follicle of larva in third stage. Lower part 

 of figure represents blind end of follicle. Wall seen at right hand 

 side is follicular wall, (v) Verson's cell ; (a) free area at blind end of 

 follicle in which Verson's cell is normally to be seen. Treated with 

 Flemming's stronger solution and Hermann's anilin-water saffranin. 

 (Leitz, homog. imm. 1/12, Oc. 3). 



Fig. 11. Verson's cell (v) with surrounding protoplasm and primary germ-cells 

 attached to it. Killed with picro-acetic acid and stained with Delafield's 

 hematoxylin. (Leitz, homog. imm. »/», Oc. 3). 



