PLATE 3 



EXPLANATION OF FIGURES 



17 Further progress of the sperm nucleus; there is no sign of abnormality; 

 25 minutes after insemination. 



18 Fusion of the germ nuclei; 30 minutes after insemination. X 1700. 



19 The cleavage nucleus; the chromatin is in very delicate threads; some of 

 the chromatin is aggregated into irregular bodies; 60 minutes after insemination. 

 X 1700. 



20 Later stage in the formation of the chromosomes; 60 minutes after insemi- 

 nation. 



21 Just before the prophase. X 1700. 



22 Prophase. The injured chromatin has assumed a variety of shapes, and 

 is irregularly distributed. X 1700. 



23 Anaphase of the first cleavage; the injured chromatin is lagging behind. 

 X 1700. 



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