202 Mr. F. S. Conant on the Ghcetognaths. 



observed heretofore. The structure of the ovaries is such 

 that no direct course is offered to the exterior, and it has been 

 a matter of some speculation with the authors Jiow the eggs 

 do get into the ducts. The ovaries are two bilateral cylin- 

 drical bodies situated in the posterior part of the body-segment. 

 Along the outer edge of each there extends a duct, which 

 opens to the exterior laterally at the level of the posterior end 

 of the ovary. This is called by Hertwig * the oviduct. By 

 Grassi f, since it is very often found to contain spermatozoa, 

 it is called the " ovisperm duct." A glance at fig. 1, which 

 represents a cross section through the body of Sagitta hispida 



Fig. 1. 



Cross section of Sagitta hispida, with eggs still in the ovary. M, muscle ; 

 B C, body-cavity; /, intestine ; GJiJ, germinal epithelium ; O, ova' 

 rian eggs ; H S, receptaculum seminis ; F, lateral fin. 



in the region of the ovaries, will show that the ova are sepa- 

 rated from this duct by a layer of cells of the germinal epithe- 

 lium. This extends between the ova and the duct throughout, 

 and leaves no clearly "marked communication, through which 

 the eggs might pass, at either the anterior or the posterior end 

 of the ovary. Hertwig supposes that the eggs pass into the 

 duct near its opening posteriorly, being probably pressed 

 through the intervening germinal epithelium. He con- 

 cludes : — " 1st meine Deutung richtig, so wiirde nur das 

 hintere Ende des Oviducts zur Ausfiihrung der Eier dienen, 

 und gleichzeitig den Ort abgeben, wo die Befruchtung erfolgt, 

 dagegen wiirde der grossere blind geschlossene Theil des 



* " Die Chsetognathen," Jenaische Zeitschr. Bd. xiv. (1880). 

 + ' Fauna und Flora d. Golfes von Neapel/ no. 5 (1883). 



