908 
the egg, at a place therefore which wholly corresponds to what 
we found in Rana fusca. lt may be observed, that the boundary 
between the darker and lighter hemispheres has wandered downward 
Fig. 2. Egg of Rana esculenta, marked on May 
6 in the eight-celled stage at the points a and b. 
First appearance of the blastopore (b/.) From the 
dorsal side, May 7, 2.30 p.m. 
a 
Fig. 3. The same egg, from the side, dotted zone 
asus: ley 
a considerable distance parallel to itself, away from the animal pole, 
as appears from a comparison with fig. 1, which as a matter of 
