PLATE 5 
EXPLANATION OF FIGURES 
Photomicrographs of late cleavage stages; all figures except 2 and 5 were 
photographed in the living state in Ringer’s solution; figs. 1 and 7 by reflected 
light; figs. 3 and 4, by transmitted light. 
1 Litter No. 314. x8. 
2 Ovum No. 314 (2); 13th section (total 19); 28 cells in the incomplete 
blastocyst wall and 2 cells in cavity, of which only one cell is shown; the cells 
are highly vacuolated; Bouin; 5u. X 200. 
3 Several eggs from litter No. 337; about 16-celled stage; the peripheral 
arrangement of the blastomeres is well seen; compare fig. 4, below, and fig. 9. 
pli. X82: 
4 Litter No. 337; one egg with the albumen has been removed from its shell 
membrane. X 36. 
5 Several eggs in cleavage stages and young blastocysts, stained in Dela- 
field’s haematoxylin and photographed in oil of wintergreen; the albumen is 
darkly stained in some cases; see accompanying text fig. 6for key. X 16. 
f= \-344 
VON 3398 
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3396) “e NF ip 
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Ze 
7 @\ 
(Ge mS] aye 3440) 
tS 
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Fig. 6. Key to figure 5, plate 5. 
6 One egg of litter No. 342 shown in fig. 7; late cleavage stage, about 26 cells. 
x 36. 
7 Litter No. 842. X 8. 
106 
