BM 



BF 



A L 



FIG. 12. A. SAGITTAL SECTION OF EMBRYO SHOWN IN FIG. n, 



D, SHORTLY BEFORE THE CLOSURE OF THE BLASTOPORE. (After 



Marshall.) 



B, blastopore. B F, fore-brain. B H, hind-brain. BM, mid-brain. //, 

 entoblast. L, liver. M. mesoblast. MN, mesenteron. N, notochord. 7VC, 

 neurenteric canal. /*, beginning of pituitary body as in growth of ectoblast. 

 PD) proctodseum. /?, rectal diverticulum of mesenteron. 6", central canal of 

 spinal cord. F, yolk-cells. 



B. SAGITTAL SECTION OF EMBRYO SHOWN IN FIG. ir, E, SHORTLY 



AFTER THE CLOSURE OF THE BLASTOPORE. (After Marshall.) 



BF, fore-brain. B H, hind-brain. BM, mid-brain. CH } notochord. M, 

 mesoblast. N C, neural tube. N T, neurenteric canal. PN, pineal body. P T, 

 pituitary body. T I, intestinal region of mesenteron. TP, pharyngeal region of 

 mesenteron. U, proctodseal or cloacal opening. W, liver. J-', yolk-cells. 



33 



