THE SPERMATHECA OF EURYCEA BISLINEATA. 259 



Although deep folds and spurs in the walls of the cloaca admit 

 of great expansion of the region it does not seem possible that 

 more than one egg could pass at a time, and during the progress 

 of this egg down one side of the cloaca corresponding to the 

 oviduct from which it has proceeded the other passage must be 

 entirely occluded by the pressure of the central fold against the 

 opposite wall. Thus each egg after being squeezed through this 

 crowded region of the cloaca arrives in the larger, freer space at 

 the opening of the spermatheca. The distance from the opening 

 of the oviduct to the mouth of the spermatheca is not over one 

 half a millimeter. 



The posterior wall of the fold and an extended area of the 

 dorsal wall of the cloaca surrounding the opening of the sperma- 

 theca is lined with the delicate columnar epithelium otherwise 

 singular to the central tubules of the spermatheca. The peculiar 

 function of these cells can be guessed at; they secrete a substance 

 which attracts spermatozoa. During egg-laying the smooth 

 musculature of the spermatheca is probably affected by the 

 convulsions of the entire region and spermatozoa are forced out 

 from the necks of the flasks into the central tubule. Thus 

 disturbed they may swim about and into the cloaca within the 

 secretions of the columnar cells, however, thus preventing any 

 loss. This secretion, as has been stated before, seems not to be 

 mucin or any staining substance but is probably acid. Pfeffer 

 has shown that malic acid is a common attraction for spermatozoa 

 in ferns and Jordan ('91) believes it must be responsible for the 

 attraction of spermatozoa to the spermatheca. 



But the substances surrounding the egg as it is released into 

 this region of the cloaca must in some manner offer greater 

 attraction and the egg is probably surrounded with a numerous 

 gathering of spermatozoa. It is not known whether one of these 

 will penetrate the egg membrane immediately before it leaves 

 the cloaca, or whether the whole group will promptly be expelled 

 from the vent, one sperm gaining entrance and the rest perishing 

 during attachment. There is no record of newly laid eggs being 

 examined for impotent spermatozoa adhering to them. 



The theory of the attraction of the columnar cells of the area 

 around the mouth of the spermatheca also accounts for the 



