PLATE 6 
EXPLANATION OF FIGURES 
Mostly unilaminar blastocysts. 
1 Group of young unilaminar to early bilaminar blastocysts photographed 
in oil of wintergreen; fixation mostly by solutions containing osmic acid; for 
identification of individual eggs see accompanying illustration, text fig.7. X 16. 
2 Group of blastocysts stained in Delafield’s haematoxylin and cleared in 
oil of wintergreen; Bouin; see accompanying illustration, text fig. 8 for key. 
x 16. 
3 Section 13 through ovum No. 88 (7), reconstructed in fig. 21, pl. 16; 18 
sections In series; 87 cells, including 5 entoderm mother cells; Hill’s fiuid. > 200 
REIS | 
fy \ 2 f 
356(@) 
Z Ya 
43903} 356(D 
© JLsse 
292(3) ASN 7% 
= eS Ca: 
KN 8 « @ 292 
‘t e as \ iS j 
SALON “314 05) 
(—292¢2) 
ars 
\ 3144) 
)@) 
Ye 320% ; 
Fig. 7. Key to figure 1, plate 6. Fig. 8. Key to figure 2, plate 6. 
4 Just completed 32-celled blastocyst No. 314 (5), 9th section (total 19 sec- 
tions); Hill’s fluid;-54; compare fig. 1, pl. 5, and fig. 2 above. X 200. 
5 Litter No. 292, photographed alive in Ringer’s solution.  X 8. 
6 Section 10 through the 46-celled, incomplete blastocyst No. 292 (4), also 
seen in fig. 2 above; 19 sections in series; no entodermal cells; Hill’s fluid; 5y. 
x 200. 
7 and 8 Ovum No. 298 (1); fig. 7, whole egg, X 30, in aleohol (compare fig. 
7, pl. 2); fig. 8, 6th section showing column of entoderm mother cells; 21 sections 
in series; 64 cells, including 4 entoderm mother cells; Hill’s fluid; 54. X 200. 
108 
