PLATE 4 
EXPLANATION OF FIGURES 
Late cleavage stage as illustrated by litter No. 336. 
1 The living eggs as photographed in Ringer’s solution by transmitted 
light. xX 36. 
2 Two eggs of the same litter; the peripheral arrangement of the blasto- 
meres is apparent. X 82. 
3 32-celled ovum No. 336 (5); blastocyst still incomplete; 9th section (total 
20); Flemming; 5u. X 200. 
4 30-celled ovum No. 336 (4); incomplete blastocyst; section taken through 
middle of ovum (about 19 sections); Flemming; 54. X 200. 
5 The eggs of litter No. 336 photographed by reflected light in Ringer’s 
solution. X 8. 
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