PLATE 3 
EXPLANATION OF FIGURES 
Photomicrographs of tubal ova and early cleavage stages in uterine eggs. 
1 Two eggs of litter No 313, photographed in the living state in Ringer’s 
solution by reflected light; considerable albumen has been deposited. 130. 
2 Litter No. 351’, photographed in Ringer’s solution by transmitted light; 
a small ring of albumen is seen. XX 56.5. 
3 Section throught ovum No. 313 (4); 10th section (total in series 19); polar 
body shown above; the albumen is darkly stained with Delafield’s haematoxylin ; 
yolk stained with osmic acid; Hill’s fluid; 54. X 200. 
4 2-celled ovum No. 306 (2); 10th section (total 21); compare C and D, text 
fig. 4; Hill’s fluid; 54. X 200. 
5 4-celled ovum No. 173 (5); 11th section (total 19); aceto-osmic-bichro- 
mate; du. X* 200. 
6 and 7 Sections 9 and 14 through ovum No. 299 (5) showing four small 
blastomeres and much extruded yolk; Hill’s fluid; 54. X 200. 
8 14-celled ovum No. 193 (6); 8th section (total 17); two large cells (of which 
one is cut longitudinally in section) have undergone nuclear division; aceto- 
osmic-bichromate. X 200. 
102 
