FIG. 51. SAGITTAL SECTION OF AN EMBRYO CHICK OF 82 HOURS. 

 (After Duval.) 



B, spinal canal, BP, lung. C 1 , 

 -fold. 



A/, allantois. Ant, amnion. Ao, aorta. 



bulbus arteriosus. C 2 , ventricle. C 3 , auricle. Cam, bottom of head-fold. Ch, 

 notochord. CM, wall of neural tube, CV , cerebellum. GP, pineal gland. HP, 

 hypophysis. IA, posterior end of fore-gut. IP,, hind-eut. MA, rudiment of 

 wing. Ma, mesoblast of allantois. PC, pericardium. Fh, pharynx. PP, body 

 cavity. V 1 , V*, and If 3 , fore-, mid-, and hind-brain. VB, liver. VH, cerebral 

 hemisphere. VJ, umbilical wall. VOM, vitelline vein. JTJT, place of interruption 

 of section, part of the dorsal region being omitted. 



153 



