30 



ATLAS OF THE FERTILIZATION AND KARYOKINESIS OF THE OVUM. 



the chromosomal vesicles of the preceding stage. The remains of the centrosphere, scarcely defined, surround the 

 nuclear vesicles. 



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Fig. XVIII. 



Fig. XVIII. — The egg beginning to divide (1000 diameters). 

 The chromatic vesicles have conjugated, leaving three larger vesicles on one side and two on the other. These vesicles lie in the interior of the shrunken centrosphere. " Zwischen- 



korper" (above Z) a lenticular mass of blue granules. (Phototype 35.) 



Plate IX. Phototype 36. 

 First Cleavage nearly Completed. 



The eo-o- has nearly divided into two and the nuclear vesicles have fused on each side to form a rounded daughter- 

 nucleus traversed by a very fine and pale reticulum of chromatin, and still surrounded by the remains of the centrosphere. 



The spindle-fibres have entirely disappeared, leaving the aster as a large horseshoe-shaped mass of granular 

 rays extending around the nucleus. 



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Fig. XIX. 

 Fig. XIX. — Two-cell stage immediately after division, a few minutes later than the last. 



The nuclear vesicles of the last stage have fused to form in each cell a small daughter-nucleus still surrounded by the remains of the centrosphere. The inner portion (towards the 



division-plane) of each aster, originally a part of the spindle, has disappeared. (Phototype 36.) 



