652 
J. T. PATTERSON 
19 
ee 
a 
— 
= 
a, 
SAK 
15 
Fig. 10 Median section of the inner cell-mass of blastocyst No. 296. This 
specimen shows with special clearness the formation of the entoderm. X 728. 
Fig 
lil 
A section taken slightly to the side of the center of the inner cell-mass 
of blastocyst no. 311. X 596. 
Fig 
Fig. 
Fig. 
Fig. 
Fig 
. 12 
13 
14 
15 
aG 
Outline of the marginal entodermal cells from blastocyst No. 300. 
Marginal entodermal cells from blastocyst No. 320 (see plate 1). 
Median section of the inner cell-mass of blastocyst No. 249. X 1190. 
Median section of the embryonic spot of blastocyst No. 340. X 1190. 
A section passing through the center of the ectodermal mass of speci- 
men No. 316. The sections are not quite perpendicular to the surface of the mu- 
cosa, and consequently the point of attachment does not show in this section 
(see plate 2). > 218. 
