PLATE 5 



EXPLANATION OF FIGURES 



26 and 27 Egg 1 hour after fertilization. Anaphase; spindles, chromosomes 

 and centrosomes of a well fixed egg-figure 2G. (Zenker-formol) and of a badly fixed 

 egg-figure 27 — (Zenker). 



28 Nucleus of an egg 50 minutes after fertilization. Thickening of the chro- 

 matin net before breaking into chromosomes. 



29 and 30 Nuclear regions of egg 80 minutes after fertilization. The chromo- 

 somes become vesicular and flow together. 



31 Blastomere of an egg 100 minutes after fertilization. Achromatic nucleus 

 still showing the outlines of chromosomes; chromatic granules uniformly dis- 

 tributed within the nucleus between the vesicular chromosomes and in the 

 cytoplasm. 



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