Fk;. 68. — Transverse section of an embryo of the fourth 

 day, passing through the anterior part of the lung rudi- 

 MENTS. (After Duval.) 



Af/i, amnion. Ao, aorta. BP^ bud of lung. C2 and C3, heart. CC, Cuvier- 

 ian duct. Cam, amniotic cavity. CO, chorion. 7-4, fore-gut. Vva^ anterior 

 branch of vitelline vein, l'/, wall of umbilical stalk, yjif, mesoblast of peri- 

 cardium. 



208 



