Mr. F. S. Conant on the Ghcetognaths. 205 



The act of laying was seen by Boveri * in 8. hipunctata. 

 After describing the way in which the eggs were extruded, 

 simultaneously from both sides and very quickly, with active 

 movements of the animal, he adds : — '' Wobei dieselben um 

 die enge Austrittsoffnung zu passiren aus ihrer kugeligen 

 Form in eine gestreckte Wurstform iibergingen, die im 

 Wasser allmahlich zur Kugelgestalt zurlickkehrte." This 

 description applies perfectly to S. htspida, the " Wurstform," 

 however, being first produced by the crowding of the eggs in 

 the duct, and afterwards increased by the passage through 

 the narrow orifice. The orifice is at right angles to the main 

 axis of the duct, so that the crowding has the result of 

 presenting the eggs with their longest diameter in the direc- 

 tion of the orifice. 



It has already been mentioned that the so-called ovisperra 

 duct, into which the eggs apparently pass, is found to contain 

 spermatozoa, and the inference would be that the eggs pass 

 into the mass of spermatozoa and are there fertilized. I 

 found last summer that soon after the eggs begin the process 

 of constriction the previously active movements of the sperma- 

 tozoa cease ; that after the complete passage into the oviduct 

 the spermatozoa are held, as it were, congealed in a longitu- 

 dinal streak external to the eggs ; that when the eggs are laid 

 there is no noticeable diminution in the number of sperma- 

 tozoa, and that their active movements are later resumed. 

 This suggested that the passage was not into the " ovisperm 

 duct," and sections of material preserved at these stages 

 confirmed the supposition. Fig. 3 shows that the spermatozoa 

 are kept in the " ovisperm duct " {R S) apart from the ova, 

 and that the latter have made their entrance into a new and 

 apparently temporary channel between the germinal epi- 

 thelium and the epithelium of the " ovisperm duct." The 

 latter is therefore only a receptaculum seminis, as Hertwig 

 supposed. It may be objected that the spermatozoa are, as it 

 were, sealed up by a secretion of mucus about them, and that 

 this, in the hardened material, gives the appearance of a 

 membrane ; but the occurrence of nuclei seems to show that 

 the structure is a definite one. The walls of the oviduct did 

 not show any such nuclei, and the existence of an epithelial 

 lining in it is doubtful. 



Of course the foregoing applies only to S. hispida^ and 

 cannot be at once assumed to be the case in all Chsetognaths. 

 It is probably the case, however, for S. hispida is a very 

 typical form. Spadella scJiizoptera offers some collateral 



* 'Zellen-Studien,' Heft iii 1890, p. 18, 



