PLATE 1 



EXPLANATION OF FIGURES 



1 to 25 are all drawn from whole mounts made by the smear method. 



1 Freshly deposited fertilized egg, showing the sperm, oocytic nucleus, and 

 nucleolus. X 620. 



2 Freshly deposited unfertilized egg, showing the oocytic nucleus and nucleo- 

 lus. X 620. 



3 Fertilized egg taken twenty-five minutes after oviposition. 

 The first maturation spindle is in the late anaphase stage. X 620. 



4 to 10 are all drawn from the same preparation. 



4 The second maturation spindle is in the late anaphase stage. The first 

 polar body chromatin is seen at A. The egg is unfertilized. X 620. 



5 Fertilized egg in which the second maturation is completed. The female 

 pronucleus {B2) is migrating toward the sperm. X 620. 



6 Fertilized egg with two pronuclei close together. The polar nucleus (P) 

 is in the process of formation. X 620. 



7 A similar egg showing the two pronuclei in contact. X 620. 



8 A stage showing the two pronuclei conjugating. X 620. 



9 An egg showing the fertilized or first cleavage nucleus. X 620. 



46 



