SECOND MONTH 



85 



the extra-embryonic coelom. With the enlargement of the amnion the vitelline and 

 abdominal stalks are bound up together in a tubular prolongation of the membrane 

 to form the umbilical cord. At the end of the month the cord is about 10 mm. 

 in length, and still contains at its attachment the primary coils of the small 

 intestine. The embryo enlarges greatly, but not so rapidly as during the first 

 month. The back is straightened and the head uplifted, and in consequence the 



FIG. 116. CHORIONIC VESICLE AT THE END OF THE FIRST MONTH, Magnified. 

 (From a preparation by Dr. J. H. Teacher.) 



The vesicle has been opened ; the embryo, closely invested by the amnion, is seen attached by the 

 abdominal stalk to the chorion. 



extreme curvature is to some degree undone. The tissues become condensed and 

 opaque, so that the internal organs can no longer be made out. The head 

 remains relatively very large, being at the end of the month nearly as large as the 

 body of the embryo. 



At the end of the fifth week the embryo measures, from neck to breech, 

 about 12 mm., at the end of the sixth week about 17 mm., at the end of the 

 seventh week about 20 mm., ajid at the end of the second month about 30 mm. 



