402 MINOT. (Vo. II. 
Cut 20, c, and with a higher power in Cut 22, c. They vary 
much in appearance: the cells are more distinct in the small 
patches, but are less individual in the large patches, owing to 
the spread of the process of degeneration into the layer, Cut 22, ¢. 
The cell bodies are lightly stained, and the granular nuclei are 
not very sharply defined and vary in size and shape. The cellu- 
MES 
Cut 22,— Placental chorion of an embryo of seven months; vertical section 
through the ectoderm and portion of the adjacent stroma. mes, mesodermic stroma; 
¢, cell layer; /%, fibrine layer; ef, remnant of epithelium. X 445 diams. 
lar layer is always sharply defined against the stroma, although 
there is no true basement membrane, but towards the outer 
layer of the ectoderm its boundary is sometimes distinct, some- 
times lost in a gradual transition. 
The outer layer of the ectoderm of the frondosum is even 
more variable. As stated by Kastschenko, it is primitively a 
dense protoplasmic reticulum, with nuclei in a single layer and 
