680 



MANUAL OF PHYSIOLOGY. 



forward, and soon lose their cavities which at first communicated 

 with those of the ventricles. 



Middle Cerebral Vesicle. By the cranial flexure the brain is 



Chick on the third day, seen from beneath as a transparent object, the head being 

 turned to one side. (Foster and Balfour.) a.' False amnion. a. Aranion. Off. Cere- 

 bral hemisphere. F.B., M.B., H.B. Anterior, Middle, and Posterior cerebral vesicles. 

 op. Optic vesicle, ot. Auditory vesicle, ojv. Omphalo-mesenteric veins. Ht. Heart. 

 Ao. Bulbus arteriosus. Ch. Notochord. Of.a. Omphalo-mesenteric arteries. Pv. Pro- 

 tovertebra?. x. Point of divergence of the splanchnopleural folds, y. Termination of 

 the fore gut, V. 



bent at the junction of the first and second cerebral vesicles, the 

 first cerebral vesicle is thus turned downward, leaving the second 

 vesicle as the most anterior part of the brain. 



