382 



VERNON L. KELLOGG. 



In the larval silkworm there may be noted on the dorsal wall 

 of the fifth abdominal segment two low tubercles, rather dark 

 colored. Directly beneath these spots lie the developing repro- 

 ductive organs (ovaries, testes). By dissecting a number of 



FIG. 4. Section (dorsal third) through male Bombyx larva, just after the second 

 moult ; //, heart ; al. c, alimentary canal ; t, t, testes. 



larvae in their last or next to last intermoulting period, a marked 

 difference will be noted in the size of the organs in different in- 

 dividuals. By dissecting out the organs and sectioning them, 



FIG. 5. Section (dorsal half) through female Bombyx larva, just after the first 

 moult ; k, heart ; al. c, alimentary canal ; oz>, ov, ovaries. 



constant marked histologic differences will be seen in the two 

 sizes of organs. As a matter of fact the larger are ovaries, with 

 well-developed rudiments of egg-tubes, the larvae possessing 



