28o 'Journal of Comparative Neurology arid Psychology. 



days) showed but four eggs left in the body and these were well 

 back in the ovariole. 



In Series 13 both head and thorax were removed, either before 

 or after mating. Such an abdomen, carefully protected from 

 external stimulus, produced no eggs, nor is there any extension of 

 the alluring glands. The average length of life, however, is 

 reduced to five days. 



With the dethoraxed abdomen, persistent efforts upon the p^rt 

 of the male failed to perfect a mating. The difficulty seemed to 

 be partly at least a mechanical one due to the continuous projec- 

 tion of the ovipositor in egg laying position. The tone of the 

 muscles moving the ovipositor was apparently lost, for no stimu- 

 lation was sufficient to induce its total withdrawal. No test was 

 applied to determine whether or not the tone of the sphincter 

 muscles surrounding the copulatory pore was also lost. 



In Series 14 the thorax was removed from the moth after mating 

 had taken place. In every case, as shown in Table VI, applica- 

 tion of stimulus was followed by a group of eggs. The size of the 

 group was as variable as in the normal or decapitated moths, but 

 no more so. The length of life averaged five days, as in the dethor- 

 axed, non-mated moth. 



The ovipositor moved from side to side now with the same pre- 

 cision as in the normal or decapitated insect, but was rarely entirely 

 withdrawn beneath the anal plates (frequently partially with- 

 drawn). In the absence of the legs, the body was dragged from 

 side to side simply by the action of the muscles of the abdomen. 

 No attempt was made to obtain the full quota of eggs under this 

 condition, but there was no reason to believe that it might not have 

 been obtained by persistent stimulation. 



The factor seeming to control the functioning of the ovipositor 

 was determined with moths in the dethoraxed condition. While 

 the decapitated insect experiences no difficulty in righting itself 

 when placed upon its back, the dethoraxed moth, when so placed, 

 makes absolutely no effort to right itself. This reflex has appar- 

 ently disappeared with the thorax. In a stimulated abdomen 

 lying in this position (that is, upon its back), the ovipositor is 

 extended for its full length. The sides of the abdomen are slightly 

 drawn in as when an insect is making a forced effort to oviposit. 

 (This movement has been observed in both normal and dethoraxed 

 moths.) The egg is ready to be expelled, but the ovipositor fails 



