No: 2.| DEVELOPMENT OF THE HUMAN COELOM. 453 
the two unite at this point. As the embryo grows, the union 
of amnion and chorion extends. At the end of the fourth 
week the extraembryonic coelom is still very large ; at the end 
of the fifth week the space between the embryo and chorion is 
divided equally between the amnion cavity and the coelom ; 
at the end of six weeks the extraembryonic coelom has 
disappeared. 
BALTIMORE, May 5, 1896. 
