STRUCTURE AND GROWTH OF DOMESTICATED ANIMALS. 651 
consists now of four masses of equal dimensions (fig. 164) ; and 
so the process goes on. Each quarter of the yolk divides itself 
again into halves, so that we next have eight such bodies (fig. 
Fig. 158. Fig. 159, 
Ovarian egg of rabbit. Copied from Bis- Ovarian egg of rabbit, freed of the cells which 
choff’s embry ology na the rabbit. Mag- aiia round the zona pellucida in fig. 158. Copied 
nified 125 diameter: om Bischoff. ypas 125 times. The ger- 
native ‘poses shines through the yolk as a 
Hane ape 
Fig. 160. Fig. 161. 
The same ovarian egg of the rabbit as in 
Be. 159, opened with a needle. The yolk, 
ith the germinative vesicle and dot are 
flowing out, outed from Bischoff. Mag- 
nified 125 tim 
= F rabbit and dog, represen in 3 
160, is very striking. 
165) ; first, irregular in shape, but very soon assuming the form of 
spheres, which fill the cavity of the yolk-membrane. Eight balls, 
as it were, resulting by spon- 
taneous division in the forma- 
tion of a mulberry-like body 
as is represented in fig. 165; 
and this is divided again, until 
the eight have become sixteen 
(figs. 166 and 167), the six- 
teen thirty-two (fig. 168), the 
inyo sixty-four, and so on until the whole of that mass is 
Separated into little granules which are about as small as the prim- 
itive cells of which the yolk consisted (fig 169). We have then a 
Fig. 162. Fig. 163. 
SISA 4 
