THE LATER DEVELOPMENT OF THE CHICK 



329 



I 3 



t oe 



9 VII I 



1C 



ao 



cv 



B 



dC 



FIG. 130. Models of the pharynx and associated structures in the chick. 

 After Kastchenko. A. Ventro-lateral view of pharynx at the beginning of the 

 third day. B. Lateral view of the pharynx and associated nervous and vascular 

 structures, at the end of the third day. Nervous structures are left unshaded; 

 arteries in solid black; veins lightly stippled; pharyngeal structures darkly 

 stippled, a. Auditory sac; aa, aortic arches; ao, dorsal aorta; cf, choroid fissure; 

 cv, posterior cardinal vein; dC, ductus Cuvieri; ej, external jugular vein; gV, 

 Gasserian ganglion of V cranial nerve; gVII, geniculate ganglion of VII cranial 

 nerve; gVIII, acustic ganglion of VIII cranial nerve; glX, ganglion petrosum 

 of IX cranial nerve; gX, ganglion nodosum of X cranial nerve; h, hypophysis; 

 ic, internal carotid artery;/, internal jugular vein; /, rudiment of larynx; o, oral 

 evagination of fore-gut; oe.ossophagus; op, optic vesicle enclosing lens; p, pulmon- 

 ary artery; pIX, placode of IX cranial nerve; pX, placode of X cranial nerve; 

 s, stomach; S, Seessel's pocket (preoral gut); st, stomodaeum; t, rudiment of 

 trachea; 1-4, first to fourth visceral pouches (or their ventral portions, in B) ; 

 Id, 2d, dorsal portions of first and second visceral pouches; IX, glossopharyngeal 

 nerve; X, vagus nerve; XI, hypoglossal nerve. 



