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BOARD OF AGRICULTURE. 



itself into two halves again, so that the yolk consists now of 

 four masses of equal dimensions 

 (fig. 11) ; and so the process goes 

 on. Each quarter of the yolk di- 

 vides itself again into halves, so 

 that we next have eight such bodies 

 Fig. 11. (fig. 12) ; 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, re- 

 sulting by spontaneous division in the formation of a mul- 



Fig. 12. 



Fig. 13. Fig. 14. Fig. 15. 



berry-like body as is represented in fig. 12 ; and this is di- 

 vided again, until the eight have become sixteen (figs. 13 

 and 14), the sixteen thirty-two (fig. 15), the thirty-two sixty- 

 four, and so on, until the whole of that mass is separated into 

 little granules which are about as small as 

 the primitive cells of which the yolk con- 

 sisted (fig. 16). We have then a well-kneaded 

 yolk-mass very similar to what the primitive 

 cell was, only that, instead of simple yolk- 

 cells, it now consists of an innumerable quan- 

 Fig. 16. tity of little spheres which have resulted from 



the spontaneous division of the whole into successively multi- 

 plied halves. There is, however, this diflerence, — that on one 

 side of the egg there is, when this process is completed, a 

 larger number of these small balls or globules than on the 

 other, and they are more whitish. The difference arises from 

 the fact that the balls multiply more on one side than on the 

 other. In quadrupeds this process of self-division pervades 

 the whole yolk, so that in the centre and on the periphery, 

 and on all sides, it is evenly divided, except that on one side 

 the spheres are somewhat smaller and also somewhat more 

 whitish. In the yolk of a hen the process is w^idely differ- 

 ent, and has been known only for a comparatively short time, 

 for in the hen the process also takes place before the egg is 



