PLATE 3 
EXPLANATION OF FIGURES 
10 a,106,10c,10d Four drawings from the same section; 10a drawn with Zeiss 
2 mm. apochromatic objective and No.6 compensating ocular; 106, 10c, 10d 
drawn with Zeiss 2mm. apochromat and no. 12 compensating ocular; 10 6 is the 
sperm mucleus of the same egg; 10 c and 10 d are from the following sections to 
show the entrance point with tail and middle piece on the membrane. Fifty-four 
minutes after insemination. Rotation of the sperm head and cone, and origin of 
the sperm aster from the pole of the nucleus opposite to the cone. Prophase of 
the second maturation division. 
11 Sixty-four minutes after insemination. The sperm head has penetrated 
within the layer of yolk, and has separated from the cone, which does not appear 
after this stage. In the next section another sperm centrosome and aster appear; 
the sperm centrosome has divided. 
12 Sixty-seven minutes after insemination. Sperm amphiaster with equal 
poles; spindle formation beginning between egg and sperm centrosomes. Ana- 
phase of second maturation spindle. Drawn at stage level with Zeiss 2 mm. 
apochromatic objective and compensating ocular no. 6. 
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