EMBRYOLOGY. 149 



(g) The formation of the head by lateral and 



anterior folds. 



Sketch five or more different regions. 

 V. The Second Day. 



1. Surface. 

 Observe : 



(a) The area vasculosa. 



(b) The sinus terminalis. 



(c) The amnion. 



(d) The vesicles of the brain. 



(e) The eye. 

 (/) The ear. 



(g) The lateral outline of the embryo. 



(h) The omphalo-mesenteric veins and the heart. 



(t) The dorsal aortse (?). 



After studying the heart and veins from the 



dorsal side, turn the slide over and examine 



the ventral aspect. 

 Sketch under AA 2. 



2. Sections. 



Beginning at the posterior end observe the 

 structures seen in the first day (see IV. 2. 

 (a-g.), and In addition : 



(a) The Wolffian ducts. 



(b) The dorsal aortse. 



(c) The spinal ganglia. 



(d) The omphalo-mesenteric veins. 



(e) The heart. 



(/) The auditory vesicles. 



