28 



WALTER K. FISHER, 



presently to be described. However, the blood, circulating through the 

 membrane between kidney and gonad, is directly under the renal 

 epithelium, and is thus subject to its action. A very small portion 

 does pass into the dorsal vascular network, direct from the gonad, 

 while some may reach the vessels of the visceral circulation and 

 thence arrive at the kidney. I have not been able to demonstrate 



rAe^S 



Fig. K. The gonad has been removed from Fig. J, to show the manner in which 

 blood from gonad reaches median sinus and mantle. B. S buccal sinus, Med. S median 

 sinus emptying posteriorly into mantle circulation at M, R.K cavity of right kidney, 

 X, X' membrane separating gonad from right kidney, composed of coelomic epithelium 

 and renal epithelium fused, the blood sinuses including the median sinus, occupying 

 space between these two epithelia, Z, Z' line of attachment of above membrane to 

 muscular body wall, Y, Y' point where vessels leave gonad to enter membrane. 



this, however, as it is beset with considerable difficulty. In conclusion 

 it might be well to state that the entire circulation of the gonad is 

 closed, and that the space about the gonad is not a primary body- 

 cavity or pseud-haemal sinus as Miss Willcox believed to be the 

 case in Acmaea fragilis, but almost without doubt appertains to the 

 secondary body cavity or coelom. 



