McCracken, Egg-laying Apparatus of Silkworm. 273 



After separation, if the male was left in the mating box with the 

 female, the full quota of eggs were always oviposited by the head- 

 less female. If, however, the male was removed immediately 

 upon separation, no eggs followed. In the former cases, there- 

 fore, eggs were no doubt brought about by stimulation of the abdo- 

 men by the movements of the male. In several observed cases this 

 was true. While ovipositing was in progress, mating could not 

 take place, since the extrusion of the ovipositor served as an effi- 

 cient barrier. The continual rubbing of the abdomen of the 

 female by the male, that followed failure to mate, served, however, 

 as a continual stimulation until all the eggs were oviposited. 



Eggs produced under this condition are fertilized and accom- 

 panied by the cement secretion of the colleterial glands, which 

 secures them to the surface, as in the normal insect. The ovi- 

 positor places the eggs accurately one by the side of another. The 

 legs assist the movements of the ovipositor by carrying the body 

 to the left or right, as demanded, in order to avoid placing one 

 egg upon another, when the movements of the ovipositor alone are 

 inefficient. This shows that the whole system is in perfect func- 

 tional condition — as shown even more conclusively later. 



In Series 10 and 11 the moths were either unmated (Series 10, 

 Table III) or mated (Series 11, Table IV), afterward decapitated 

 and stimulated at various intervals as indicated in the tables, by 

 pressure upon the abdomen with the fingers. In some cases moths 

 were stimulated every five or ten minutes during a certain period, 

 in others once a day only for several days in succession, in still 

 others both methods were employed. The result is the same in 

 each case. In no case were eggs produced except as a result of 

 stimulation. In very rare cases only did stimulation fail to bring 

 a response in the way of a group of eggs. In such cases the oviposi- 

 tor responded by becoming extruded, the failure of the appearance 

 of the egg was due apparently to failure of the transportation of 

 the egg along its path from ovariole to ovipositor. Failure was 

 more apt to occur when the young moth was stimulated; that is, 

 stimulation taking place before the normal time for egg laying in 

 the normal insect. This appears to indicate that the inhibition 

 of the egg-laying reflex was not completely removed with removal 

 of the head. 



The time elapsing between the stimulation and the response was 

 sometimes inconsiderable, and sometimes of many seconds' dura- 



