PLATE 2 



EXPLANATION OF FIGURES 



All the figures on this plate are from normally fertilized eggvS. 



10 Approach of male and female pronuclei. 



11 Fusion of male and female pronuclei. 



12 jNIetaphase, first cleavage spindle. 



13 Anaphase, first cleavage spindle. 



14 Chromosomes from the fourth cleavage. 



15 Chromosomes from middle cleavage stage. 



16 Chromosomes from an ego; fixed nine hours after fertilization. 

 Magnification, 2600 diameters. 



38 



