SEX DIFFERENTIATION IN LARVAL INSECTS. 



333 



them being female individuals, while the smaller are testes. By 

 dissecting \arvx of successively younger age, these differences 

 in size and histologic character may be followed back to just 



after the first moulting. 



FIG. 6. Section (dorsal half) through male Bombyx larva, just after the first 

 moult ; k, heart ; al. c, alimentary canal ; t, (, testes. 



Figs, i to 8 show, with little need of explanatory description, 

 the gross character of the histologic differences, the relative sizes 

 (in cross-section) of the two kinds of organs, and also the rela- 



FiG. 7. Section through male Bombvx larva, just before the first moult ; h, heart j 

 al. (-, alimentary canal ; v. n. c, ventral nerve cord ; /, t, testes. 



tive size of these organs in the various larval stages. I have 

 not been sure of being able to distinguish between the sizes or 

 the histologic characters of the reproductive organs in the just 



