APPENDIX 87 



and oviposit a few eggs which begin normal development. In one case 10 eggs, 

 of which 8 are now normally developing were oviposited by such an impregnated 

 part of female abdomen, this abdominal relict remaining alive ( !), i. e., flexible 

 and responsive to stimulus and capable of extruding the ovipositor and laying 

 eggs, for forty hours. 



Males with head removed can not find females, nor can they mate if placed 

 in contact with them. When the head or head and prothorax of a male is cut 

 off immediately after the male and female are in copula the female, although 

 uninjured, lays no eggs. If heads of both males and females in copulo are 

 removed no eggs are laid although both moths remain alive usually as long as 

 do unmutilated individuals. 



A silkworm moth can maintain itself right side up with antennae off or 

 with antannae off and eyes blackened, but with head off one position seems in- 

 distinguishable from another to it, i. e., it lies on one side or the other, on the 

 venter or dorsum equally willingly. The organs of equilibrium are not on the 

 antennae, then, but are lost when the rest of the head is removed. 



Sex Differentiation in Larval Insects, in Biol. Bull., v. 12, pp 380-384, 

 8 figs., May, 1907. 



Dissections and sections of larvae of Bombyx mori of various ages from just 

 after hatching to the last instar show that the reproductive organs (ovaries or 

 testes) are already in such an advanced stage of development that the distinc- 

 tion between male and female (testes and ovaries) can be recognized in larvae 

 from the time of the first moulting. Also that the just hatched larva has the 

 reproductive organs already well developed. Careful scrutiny by a special 

 student of oogenesis and spermatogensis would probably enable him to determine 

 the sex of the larva immediately on hatching. 



The sex of the silkworm is then not to be tampered with by gorging or 

 starving, and what is true of this lepidopteron is undoubtedly true of its cousins, 

 the other moths and the butterfles. It is probably also true of other insects with 

 complete metamorphosis. I recall dissections of various larvae, notably of 

 Corydalis cornuta (a neuropteron) and of Holorusia rubiginosa (a dipteron) 

 in which the reproductive organs appear of two sizes in specimens of the same 

 age : indeed in Corydalis, of two shapes. These organs need histologic exami- 

 nation. Some student should laboriously work through a long and representative 

 series of insects and settle the question as to the time of sex differentiation. 

 That is, find out whether it be true for all, as it is in the silkworm, that the time 

 of sex differentiation is obviously before, or, at latest, at very little after the time 

 of hatching. If it is true, the question of the influence of nutrition in sex 

 determination will also be settled for insects. And we need waste no more 

 time in tedious feeding and tabulating. 



Artificial Parthenogensis in the Silkworm, in Biol. Bull., v. 14, pp 

 15-22., December, 1907. 



In a clutch of unfertilized eggs oviposited by a virgin silkworm moth 

 (Bombyx mori} almost always a small number of eggs begins development. 

 This development extends to the formation of the embryonic envelopes and some- 

 times farther, and is clearly indicated to the observer by the change in color of 

 the egg from yellow to cherry or through cherry to gray. Non-developing eggs 



