No 1.] ORIGIN OF HUMAN MONSTERS. 157 
Fic. 24a.—Section through the vesicle attached to the chorion. X 25 
times. There is a multiple allantois and multiple amnion with a 
thick layer of epithelium over the vesicle. 
Fic. 24c.—A still deeper section of the vesicle, showing the irregular 
thickening of the ectoderm and entoderm. 
