1 76 A. RICHARDS. 



EXPLANATION OF PLATE VII. 



FIG. 55. Reconstruction of the female pronucleus; male pronucleus near. The 

 other polar body in the next section. Zenker, Conklin's stain. 



In the remaining illustrations the blastomeres not shown in the figure were 

 to be found in the next section. 



FIG. 56. First cleavage division. Zenker, safranin and gentian violet. 



FIG. 57. Division cutting off the second micromere. Three-cell stage. Zenker, 

 safranin and gentian violet. 



FIG. 58. Formation of the third micromere. Dotted line indicates the position 

 of the second micromere. Zenker, safranin and gentian violet. 



FIG. 59. Four-cell stage, showing reconstruction of macromere nucleus after 

 the last mitosis. Zenker, safranin and gentian violet. 



FIG. 60. Formation of the fourth micromere. Zenker, safranin and gentian 

 violet. 



