SOCIETY OF THE UNIVERSITY OF ABERDEEN. 



103 



teries are given off and pass on either side of the allantoic duct into 

 the body stalk, where they unite, forming a single trunk, which again 

 divides into two vessels. 



The Heart. The heart is in a stage very similar to that represented 



Ck 



Fig. 6. Transverse section in region of second pair of somites, x 50. 



Am., amnion ; .in., auricle ; K., ventricle ; Sp.c,, medullary canal ; C/i., noto- 

 chord ; //. .1/..S'., second somite ; d.Ao., dorsal aorta ; f.(f., fore-gut. 



F.C 



Fig. 7. Model of pharynx, x 75. Seen from the left side 

 and slightly from the front. 



.I/., mouth; Hy., hypophysis; B.Ph., bucco-pharyngeal membrane; 

 < /i.. riotochord ; /.-///., visceral clefts ; /K, fourth pharyngeal 

 pocket; Th., median thyroid ; /''.(f., fore-gut ; /,/., liver bay. 



by Born's model (1) of the heart of a rabbit embryo of 0*95 mm. length 

 model 1 (Ziegler). The heart as a whole is S-shaped, and shows 

 sinus venosus, auricle, ventricle, and just at the base of the aortic 

 stem a slight dilatation which may represent a bulbus cordis. 



