484 



The Embryology of Hylodes Martinicensis 



yolk recedes from the region where the liver is established (cf. Fig. F 

 with Figs. G and H -i-8 ) . The lengthened gut forms a loop posterior to 

 the liver and joins the yolk-mass on the right side. The bile-duct is in- 

 creased in length and in stage YIII still opens into the gut near the point 

 where the gut joins the yolk-mass (see Fig. H5, 6) ; since the gut has 

 lengthened, it seems that the entrance into it of the bile-duct has shifted 

 toward the yolk. The gall-bladder appears about stage VI as a diver- 

 ticulum from the ventral wall of the bile-duct close to the liver (Fig. F, 

 gb. cf. Fig. H5). 



Fig. I. Sagittal ~r(t mn cii st^ii^c 1 \' i ii'^ai-ly in the nuMliaii iihuici. a, aim-. : ar, archenteric 

 cavity; da. dorsal aorta; h, heart: pu, pharynx; pr. jiroctudaeum : rl, rudiment of liver 

 r'p, 1st rudiment of pancreas ; y, yolk-mass. 



Pancreas. — The pancreas develops from three rudiments. The first in 

 time of appearance is present in stage lA^ as a diverticulum from the 

 dorsal wall of the gut (Fig. Gl, I, r' p). Anteriorly this rudiment ends 

 in a solid mass of cells containing much yolk, and entirely separated from 

 the gut. The connection between the gut and this rudiment is already 

 lost in the next stage. 



Early in stage VI, a second rudiment appears as a diverticulum from 

 the dorsal wall of the definitive bile-duct nearer to the gut than to the 

 liver (cf . a later stage Figs. 116, 7, r" p) . The third rudiment arises later, 

 in the same region as the second, but from the ventral wall of the duct (cf. 

 Fig. H6, 7, r'" p). The connection with the definitive bile-duct is re- 



