318 



EMBRYOLOGY. 



wards towards the dorsal laminae, become pediculated, and 

 present a broad shovel-shaped termination (fig. 344, f t y). 



[ 490. The vascular lamina in its development follows the 

 phases of the first, or vitellicular circulation, which, as has 

 been stated, attains its height on the fourth day (fig. 346). 



Fig. 346. View of the vitellus, magnified rather more than two diame- 

 ters, exhibiting the circulation of the blastoderma completely developed : 

 a, Vitellus ; b, vena s. sinus terminalis ; &-, point of approximation to the 

 embryo of the terminal sinus, and its communication with the veins, g, g , 

 c, aorta ; d, punctum saliens, or pulsating point of the heart ; /, /, arte- 

 ries of the blastoderma ; g, g, veins of the same (one inferior, two supe- 

 rior ; sometimes there is but one above as well as below) ; e, e, the fiddle 

 or guitar-shaped area pellucida ; A, the eye. (This figure will be found to 

 correspond in almost every particular with that of Pander, tab. iv. fig. 1, 

 of his well known work, Entivickelungsgeschichte des Huhnchens im Eie). 

 The more delicate ramifications of the vessels and their numerous inos- 

 culations with the bounding sinus are omitted. 



