THE VITAL PHENOMENA OF THE CELL 



237 



of the second division following so closely on the first that the 

 resting condition was missed, an augmentation of nuclear sub- 

 stance, and an increase in the number of the nuclear segments, 

 through longitudinal cleavage, have been unable to take place. 

 In consequence, the number of segments has been diminished or 

 reduced to half the normal number. 



In exactly the same way division with reduction occurs in the 

 egg of Ascaris megalocephala during the process of ripening. 



The sperm-mother-cell corresponds to the unripe egg, or egg- 

 mother-cell. Here also eight nuclear segments, arranged in two- 

 bundles, develop in the germinal vesicle (Fig. 127 I.). After the 

 nuclear membrane has been dissolved, they arrange themselves in 

 the equator of the first direction spindle, which rises up to the 

 surface of the yolk (Fig. 127 I/.), and in the manner already 



777. 



FIG. 12-. Diagram of the development of polar-cells and tbe fertilisation of the egg of 

 Ascaris megalocephala bivalens. 



described (p. 228) forms the first polar-cell. This process corre- 

 sponds to the division of the sperm-mother-cell into two daughter- 

 cells. As before (Fig. 126 I.), each of the two unequally large 

 products of division, viz. the egg-daughter-cell and the polar-cell 



