154 VERNON L. KELLOGG. 



A number of experiments was made to determine the need, or 

 absence of need, of the principal ganglia of the central nervous 

 system in the performance of the two chief reflexes in the silk- 

 worm moth's life, viz., mating and egg-laying. 



Males mate with headless females, and the headless females, 

 after mating, lay a few eggs which develop normally, that is be- 

 come fertilized by the release of spermatozoa from the sperma- 

 theca in the female's body, are oviposited by the repeated extru- 

 sion and retraction of the ovipositor, and make the usual color 

 changes (from yellow to cherry-red and then to lead-gray) inci- 

 dental to normal development. But in no case did a headless fe- 

 male lay her full complement of eggs, in fact in no case were more 

 than a score of eggs laid (the normal number is from 200 to 350). 

 Headless females (and headless males) usually live as long as 

 unmutilated individuals, i. e., from a week to two weeks. 



Females with head and thorax cut off (and even part of the 

 abdomen) can be mated with by males, and this fractional part 

 of the female can fertilize 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 

 (!), /. e., flexible and responsive to stimulus and capable of 

 extruding the ovipositor and laying eggs, for forty hours. 



Males with head removed cannot 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 copula 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 anten- 

 nae off or with antennae off and eyes blackened, but with head 

 off one position seems indistinguishable 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 antennas, 

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



STANFORD UNIVERSITY, CALIF., 

 October 15, 1906. 



