No. 1.] ORIGIN OF HUMAN MONSTERS. 185 
entire chorion is surrounded with a mass of decidua filled with 
leucocytes. 
The magma of the ccelom is very dense and has within it 
but few migrating cells. Within the greatly distended amnion 
lies the embryo, looking much like a chick of the third day. 
The peritoneal cavity communicates freely with the exoccelom, 
in which hangs an atrophic umbilical vesicle. The lumen of the 
umibilical vesicle is filled completely with entodermal cells, its 
Fic. 115a—Embryo imbedded within the magna reticulé of the ccelom. 
Natural size. 
Fic. 115b.—Embryo attached to the chorion. 3 times. 
blood spaces are greatly distended but nearly empty, and its 
solid stem ends abruptly after it enters the body of the em- 
bryo. There is no trace of either alimentary canal or liver 
left. Rudimentary Wolffian bodies and ducts are present. 
The central nervous system is solid. The heart and large 
veins are simple in form and greatly distended with blood. 
The mesodermal layer of the chorion and its villi appear 
normal, with the exception of the tip ends of the villi, which 
are enveloped in a mass of leucocytes, 
