56 MR, T. GOODEY ON GONADIAL [Feb. 4, 



their connections with the central gastric cavity, were removed. 

 These were then stained with borax carmine for forty-eight 

 hours, dehydrated, and embedded in paralfin-wax. Sections wei'e 

 cut at right angles to the inter-radii, passing completely through 

 the pouches from the dorsal to the venti^al surfaces. In the above 

 preparation there was a considerable amount of contraction due 

 to the jelly-like consistency of the material, and, for this reason, 

 many of the parts in several of the sections were displaced from 

 their natural relations. 



From an examination of the most satisfactory complete sections, 

 however, the nature and relations of the grooves could be easily 

 made out. It was at once evident that they were not closed 

 canals similar to the normal radial canals, and that their resem- 

 blance to canals in a superficial or surface view was misleading. 



Each groove is, in fact, formed by a folding of the endodermal 

 epithelium lining the floor of the pouch and of its passage of 

 communication with the gastric cavity. This folding is shown in 

 PI. I. fig. 3, where the epithelium is seen to be raised into two 

 parallel i-idges (e), one on each side of a median vertical line, 

 which form the somewhat folded lateral walls of the groove 



{g-9')' 



In the floor of each pouch, almost completely encircling its 

 outer, lateral, and inner walls, is situated the gonad (figs, 1, 2, & 

 4, g.), in the form of a characteristic incomplete ring of sex- 

 cells, the discontinuity occurring at the point where the groove 

 enters the pouch. 



From PI, I. fig. 4 it will be seen that the endodermal epithelium 

 {e, e', e\ p^) not only lines the inner surface of the gastric pouch 

 and invests the gonad above, but also extends downwards in the 

 median line so as to form the boundaries of the gonadial groove 

 {g.g.). An epithelial stratum (e^, e') also invests the ventral or 

 oral surface of the gonad, and is continuous with that lining the 

 floor of the gastric pouch. Thus the gonad is completely 

 ensheathed by the endoderm from which the sex-cells are derived. 

 As this section passes through the point of discontinuity of the 

 gonad-ring, it will be noticed that the two halves of the ring lie 

 one on either side of a median line along which the gonadial 

 groove passes into the gastric pouch. 



The function of these problematic grooves is by no means so 

 easy to determine as their structure and relations. That they 

 have anything to do with the conveyance of food-material from 

 the gastric cavity to the gastric pouches is highly improbable, 

 inasmuch as these cavities are already in free and open communi- 

 cation with one another, A more feasible suggestion is that they 

 function as channels for the outward conveyance of the ripe 

 sex-cells when liberated from the gonads. Their position 

 in the gastric pouches and their somewhat expanded origins in 

 close relations with the encircling gonads, seem to point to this 

 conclusion. The liberated sex-cells would fall on to the floor of a 

 gastric pouch, and the gonadial groove would seem to constitute 



