PLATE 6 
EXPLANATION OF FIGURES 
59 Median section, taken in a right-left plane, of specimen No. 256. The two 
mesodermal vesicles have expanded until they now fill up the entire large extra- 
embryonic cavity; but their adjacent walls still remain, forming a double-walled 
partition between the cavities of the vesicles. X 95. 
60 Median section of specimen No. 247. It passes through plane a to b of figure 
Le 90: 
61 Asection taken through plane c tod of figurel. X 90. 
