488 



The Embryology of Hylodes Martinicensis 



In stages XI to XII, the interior of the yolk is split in various places, and 

 the fissures contain a substance which stains deeply with carmine. The 

 substance may be the product of cells that appear to be breaking down in 

 the borders of the fissures. In the next stage (XIII), the fissures have 

 formed a continuous cavity that leads into the anteriorly and posteriorly 

 differentiated gut, thus completing the lumen of the alimentary canal. In 

 the meantime, the whole yolk becomes lobed, and large portions are con- 

 tributed to the gut at once. This takes place with almost uniform regu- 

 larity; the first lobe is formed in stage XII, and from that part of the 

 yolk which immediately joins the anterioi; gut; the second is added from 

 the yolk in connection with the posterior gut. The amount of yolk is con- 



FiG. M. Cross section of statre XIV. aav, antei'ior abdominal vein; da, dorsal aorta; e, 

 differentiated portion of entoderm ; g, gut ; k, kidney ; is, lymph spaces ; pvc, posterior 

 vena cava; r, reproductive organ ; y, entodermic cells laden with yolk. 



stantly reduced in the large lobes, and finally in stage XIV the yolk is 

 found in only a small portion of the intestine (cf. Fig. M). 



A comparison of Figs. Bl, 2, 3, Fig. M, Fig. C and Figs. I, F, 0, will 

 show briefly, in review, the main facts in the history of the yolk-mass 

 and its relation to the embryo. 



There is no coiled intestine as in the vegetable feeding larva of Rana, 

 but the yolk holds the same relation in the digestive tract as it does in 

 two other yolk-laden Amphibian eggs, those of Plethodon cinereus and 

 Ichthyophis glutinosus (cf. Fig. B3 with Montgomery '01, Fig. 5 and 

 Sarasin '87, Fig. 7, and cf. Fig. X with Sarasin '87, Fig. 8) . Very much 

 the same relations appear from the descriptions to exist in Alytes obstet- 

 ricans at one period, although in this form a coiled intestine is later 

 developed. 



