SEX DIFFERENTIATION IN LARVAL INSECTS. 381 



to say here, in a word, that this "short feeding " produced no 

 apparent effect in determining the sex of the moths. 



Since these experiments I have learned a good reason why 



FIG. 2. Section through male Bombyx larva, just before the third moult ; h, heart; 

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



the nutrition of the larva, at least after its first moulting, should 

 have no effect on the sex as revealed in the moth, and this reason 

 is that the sex of each individual is definitively determined at 



FIG. 3. Section (dorsal third) through female Bombyx larva, just after the second 

 moult; h, heart; al. f, alimentary canal ; ov, ov, ovaries. 



least as early as immediately after the first larval moulting, as 

 may be readily perceived by an examination of the rudimentary 

 reproductive glands. 



