508 Howard Edwin Enders. 



the shoals. The ripe sexual products, which, as has been stated, 

 fill the general cavity and its diverticula are extruded to the exterior 

 through the nephridial pores of the sexual segments. 



I have never been able to observe the egg-laying among the ani- 

 mals on the shoals, but I have observed it in a large individual that 

 had been removed from its tube and placed in a dish of sea-water 

 for the purpose of photographing in strong sunlight. After being 

 in the direct sunlight fifteen or twenty minutes the water became 

 quite warm and the animal began to extrude its eggs. Several hun- 

 dred eggs had been extiTided free into the water when I first observed 

 the phenomenon, and many more were coming from the forward 

 segments of the sexual region. They issued from the nephridial 

 pores during the rhythmic movements of the body. These move- 

 ments, which are of a peristaltic nature, may have been the 

 means of expelling them, because they came from the pores, after 

 each compression of the segments, in short streams one egg thick. 

 Several thousand eggs were extruded during twenty minutes, after 

 which the animal was killed and preserved. Transverse sec- 

 tions of its sexual segments include eggs in the body cavity. They 

 may also be traced through the nephridia to their pores at 

 the posterior (inferior) surface of the segments (Figs.^ 4 and 

 8). Although Laffuie says "the eggs and spermatozoa accumu- 

 late in the nephridia "where they await the moment for expulsion to 

 the exterior" (italics mine), I have been unable to confirm his state- 

 ment from sections of nephridia from three of these segments, all 

 of wdiich contained comparatively few eggs in any portion — possibly 

 forty to fifty in each nephridium. Dr. E. .A. Andrews (Sept. 20, 

 1895) observed the discharge of a small number of eggs when fresh 

 sea-water had been admitted to an individual kept in a glass U-tube 

 and from this he concluded that they are discharged at high tide, 

 i. e., when fresh water is added to that in which they live. I have 

 not been able to verify this nor to determine the conditions that 

 naturally control the egg-laying; whether it occurs after a few' eggs 

 have collected in the nephridia, or whether heat and fresh water 

 supply the necessary stimulus. 



