FIG. 515. TRANSECTION OF THE SPINAL CORD OF AN EMBRYO CHICK. 



c. rod. ant., axons to the ventral roots; c. rad. post., axons to the dorsal roots; 

 col, collateral from an axon back to the gray matter; gg, dorsal root ganglion; me. 

 ant., ventral root; rac. post., dorsal root. (After van Gehuchten.) 



Head fold" 



Neuropore ./ 



Pharynx 



Vitellin vein 



Medullary groove 



nterior cerebral 

 vesicle, or pros' 

 encephalon 



Middle cerebral 

 vesicle, or mes- 

 encephalon 



Posterior cerebral 

 vesicle, or rhomb- 

 encephalon 



Heart 



Mesodermic 

 somite 



FIG. 516. RECONSTRUCTION OF THE ANTERIOR PORTION OF THE BODY OF A YOUNC 

 CHICK EMBRYO, SEEN FROM THE DORSAL SURFACE. (After Kollmann.) 



