284 "Journal of Comparative Neurology and Psychology. 



of a kind altogether different from that of the initial reflex. The 

 functioning of the ovipositor is perfected by the movements in 

 space of the legs, or in the absence of these, of the anterior seg- 

 ments of the abdomen. 



Direct Stimulation of the Commissure. — In direct stimulation 

 of the ventral commissure v^^ith an electric current, w^hich is quite 

 possible in silkworms, the response is not so determinate. Then 

 only an occasional egg follows upon stimulation. The difference 

 in response to direct stimulation and integumental stimulation 

 may be due to the fact that in integumental stimulation only those 

 neurones are affected that are in direct connection with the ovi- 

 positing machinery promoting movement, whereas in direct stimu- 

 lation through the commissure, all the neurones are similarly 

 stimulated, the inhibitory as well as those promoting movement. 



SUMMARY 



1. The vitality of the silkworm moth, as measured by length 

 of life and capacity of the reproductive system to function, is not 

 impaired by removal of the head (supra- and sub-cesophageal 

 ganglia). 



Length of life is shortened, but functioning of the reproductive 

 system is not impaired by removal of thorax (thoracic ganglia). 



2. The mating instinct is dominant in unmated moths and in 

 some way correlated with an inhibition of the ovipositing mechan- 

 ism. This inhibition is reduced in the mated moth, functioning 

 of the ovipositing mechanism then dominating. The inhibition 

 is reduced in decapitated moths, as evidenced by the early response 

 to stimulation. 



3. Effectual mating takes place several days after decapitation 

 of the female. It is impossible with the dethoraxed female. 



4. In the presence of the brain or brain and thorax, reaction of 

 the ovipositor to external stimulus is resisted. In the absence of 

 the brain, or brain and thorax, spontaneous movements cease, but 

 reaction of the reproductive mechanism to external stimulus is 

 prompt and efficient. 



5. The effectual stimulus is pressure and contact, this being a 

 stimulus to which the normal silkworm moth is constantly sub- 

 jected under normal conditions. 



6. The time duration of the reflexes centered in the last abdom- 



