THE BRAIN. 



373 



BH 



BM 



PT 



TP 



CH 



TO 



LR 



CH 



vv 



KC 



FIG. 150. A median longitudinal, or sagittal section through a Babbit Embryo 

 at the end of the twelfth day. The section is a strictly median one except 

 in two respects : the cerebral hemisphere of the left side has been intro- 

 duced in order to render the figure more complete; and the Wolffian body 

 and ureter of the right side. The terminal portion of the tail has been 

 removed. (Compare Fig. 161 for a surface view of an embryo of the 

 same age.) x 14. 



BF, cavity of fore-brain or thalamcncephalon. BH, cavity of hind-brain, or fourth 

 ventricle. BL, cerebellum. BM, cavity of mid-brain. BS, cavity of cerebral hemi- 

 sphere, or lateral ventricle. CH, uotochord. Q-P, post-anal fjut. IN, finger-like 

 process of infundibuluni. KG, Wolffian duct. KI), ureter. KM, Wolffiaii body. 

 LE, epiglottis. LG, lung. LR, trachea. PN, pineal body. PT, pituitary body. 

 B,S, sinus venosus. RT, trillions arteriosus. B,V, ventricle of heart. T, glottis. 

 TA, stalk of allantois, cut short. TO. cloaca. TH, thyroid body. TO, oesophagus. 

 TP, pharynx. "W, liver. WD, bile duct, YK, yolk-stalk, cut short. 



