292 LILLIE. 



EXPLANATION OF PLATE XXVIL 



Fig. 45. Shifting of first cleavage spindle to one end of the egg. Observe 

 that the spindle does not elongate as it moves. Stage immediately preceding the 

 metaphase. 



Fig. 46. Metaphase of the first cleavage spindle ; for the sake of clearness 

 only about one-third of the chromosomes in the section were drawn. In this 

 stage there is a single centrosome within a hollow inner sphere. The egg is per- 

 fectly round. 



Fig. 47. Anaphase. Egg slightly elongated in the plane of the spindle. The 

 inner sphere is enlarged and occupied by a delicate reticulum. 



Fig. 48. Begmning of telophase ; the spindle has shifted to its definitive posi- 

 tion ; the line of shifting is plainly marked. The outer sphere has disappeared ; 

 the inner spheres have enlarged yet further, and are occupied by a reticulum with 

 microsomes at the nodes. 



Fig. 49. Combination of two sections. Constriction in first cleavage plane 

 begun. The inner sphere has grown much more and altered its form ; its reticu- 

 lum is wider-meshed. The remains of the aster is a close-meshed reticulum (or 

 foam). The migration of the sphere substance in the larger cell is already 

 indicated. 



Fig. 50. Combination of two sections. The sphere substance has lost its 

 sharp boundaries, and in the larger cell is migrating towards one side of the cell 

 which is elongating in that direction. 



Figs. 51 and 52. Two sections of the larger cell parallel to the first cleavage 

 plane in a slightly later stage. The nucleus is yet in process of reconstruction, 

 and the sphere substance is stretching across the cell. The furrow is on the vege- 

 tative pole surface of the cell. 



