PLATE 9 
EXPLANATION OF FIGURES 
Photomicrographs of late unilaminar and young bilaminar blastocysts; figs. 
1, 4, 5, and 6, photographed alive in Ringer’s solution; the first by transmitted 
light, X 36, the last three by reflected light, X 8. 
1 Litter No. 352, blastocysts with bilaminar embryonic area (indicated by 
dark region at one pole of the vesicle); trophoblastic area very attenuated; 
compare fig. 5, pl. 12. 
2 Section through embryonic area of egg No. 352 (11); 44th section of egg 
(total 96); 26th section of blastocyst (total 66); 16th section of embryonic 
area (total 34); entoderm has begun to migrate beyond area; ,half-strength 
Bouin; 54. X 100. 
3 Section 12 of ovum No. 356 (5), of which sections 13 and 18 are shown in 
figs. 10 and 11, pl. 17; total 21 sections; Bouin; 64. X 500. 
4 Litter No. 352’; interval 15 hours; compare fig. 1; young bilaminar blasto- 
cysts; one egg has two blastocysts. 
5 Litter No. 347; partially and entirely completed bilaminar blastocysts. ° 
6 Litter No. 339, a little younger than litter No. 347, shown in fig. 5. 
114 
