well forward against the outer wall of tne left peribranchial 

 sac, Fig. 5. 'with tne anterior extension of the digestive 

 tract and the posterior prolongation of tne left peribran- 

 chial sac, the whole tract, which lies entirely on the left 

 side of the bud, comes eventually to be closely enveloped by 

 the outer wall of tne peribranchial cavity. 



The "pyloric gland" or "organe refringent " of 

 Giard arises as a tubular diverticulum from the lower ante- 

 rior face of tne enlarged portion of the digestive tract 

 which will become the stomach. Before reaching the intes- 

 tine the tube bifurcates, and each branch in its turn gives 

 off two others, which also divide, the whole system of dich- 

 otomously branching tubules finally forming a lace-work sur- 

 rounding the whole intestine. 



The development of this problematical organ is al- 

 ready well advanced at the stigo shown in Pig. 5, o .r . This 

 figure, together with Pig. 25, which shows a portion of the 

 stomach wall, leaves no doubt that the tube is directly deri- 

 ved from the digestive tract. This origin was maintained by 

 Delia "(''alle (3), but denied by Roule (25), who stated that 

 the "organe refring'nt" is not a part of the digestive 

 tract, but communicates v;ith the heart, and therefore belongs 

 to the vascular system, an opinion already held by Kuppfer. 

 (16) 



Delia Valle's vievf is also supported by Pizon (22), 

 whose description of the development of the organ in Botryl- 

 lus , agrees minutely v;ith ray observations on Perophora. 



■53- 



