ARTIFICIAL PARTHENOGENESIS IN CUMINGIA 25 



tilized egg, as far as can be told from a side view of the spindle 

 (cf. figs. 7 and 70). Up to this point, then, maturation has pro- 

 ceeded in these eggs in a manner closely approximating the 

 normal com'se of events. From here on, however, we must 

 trace separately the fate of eggs which form only one polar 

 body and that of those in which maturation is completed. 



a. Eggs with one polar body. In some eggs, a suppression of 

 the second polar body may take place, similar to the suppression 

 of the first polar body which has been described. The steps 

 are apparently the same. The spindle lies well below the sur- 

 face of the egg, and there is no attempt to form a polar body. 

 The chromosomes divide, how^ever, and go to the poles of the 

 spindle, where they form vesicles, just as the chromosomes of 

 the first polar spindle have been seen to do in other cases (figs. 

 71 and 72). The vesicles are, however, decidedly smaller than 

 those formed by the chromosomes of the first polar spindle. 

 Figure 73 shows a stage which corresponds to that of figure 56, 

 and illustrates this difference. 



The series of stages showing the fusion of the two resting 

 nuclei formed by the suppression of the second polar body is 

 by no means complete. Two small vesicles are sometimes found 

 close together, apparently about to fuse, as is shown in figure 74. 

 Also, one finds single vesicles, much larger, as represented in 

 figure 75. It seems most probable that two resting nuclei are 

 formed from the daughter-chromosomes of this second matura- 

 tion spindle, and that the nuclei fuse; but a positive statement 

 can not be made until more material has been preserved and 

 studied. 



Only two cases of normal cleavage of eggs with one polar body 

 were found in the preserved material. Of these, one is an ana- 

 phase of the first cleavage — unfortunately too late a stage to 

 show anything of the form and number of the chromosomes (fig. 

 42). The spindle is normal in appearance, but lies farther 

 from the animal pole than that of a normal egg. A 2-cell stage 

 was also found which had only one polar body. Here, the 

 cleavage plane did not pass through the polar body, but the egg 

 was otherwise normal in appearance. 



