2IO E. E. JUST. 



They may be found also attached to the vitelline membrane of 

 the eggs. If one minces a male, one procures not only sperm but 

 large numbers of corpuscles. Apparently, these are not injected 

 into the female's body (cf. Scott on A m phi-trite) . 



Since the mechanical pressure of the male, though often re- 

 peated, is not sufficient stimulus for egg-laying, it may be assumed 

 that either the sperm or some secretion with, or of them stimu- 

 lates in the female movements which bring about oviposition. 

 In some cases males after having induced oviposition in two or 

 three females cause egg-laying in a third or fourth as noted 

 above. A slight amount of this substance, therefore if such there 

 be in addition to the sperm themselves, is sufficient to initiate 

 egg-laying. The injected substance, on the same ground could 

 scarcely exert sufficient pressure to stimulate oviposition. 



I had projected for 1913 various experiments to determine 

 this point. The first experiment on the list, however, was clear 

 enough to warrant abandoning the others. I put a female in a 

 dish with no water. If a drop of sea-water be put on her head 

 there is no response. Only complete drying causes breakdown of 

 body wall. If instead of pure sea-water the minced female be 

 added there is no response. But if a drop of minced male be 

 added oviposition follows. This observation was made several 

 times. 



The following protocol from notes of the night of July 25, 1913, 

 is typical : 



Experiment. Six males cut up in water adherent to their bodies (/. e,, not dried). 

 Dried female put in this sperm suspension. No oviposition. A second female 

 placed in the sperm suspension; and a third. No oviposition. 



2. Three males cut up in three drops of sea-water. Two successive females 

 used. No oviposition. 



3. Six dried males cut up. Two dried females placed with heads in the sperm 

 suspension. Eggs laid. Next day: trochophores. 



4. Three males cut up in two drops of sea-water. Two dried females placed with 

 heads in the sperm suspension. (Both females later copulated with males and laid 

 eggs.) No eggs laid. 



Oviposition, then, is clearly brought on through the ingesting 

 of sperm with very little sea-water. 



Nereis diversicolor O. F. Muller gives birth to living young. 

 Autolytus (Agassiz) carries its larvae in a brood pouch. In both 

 of these forms there is probably internal insemination. Eisig 



