ARTIFICIAL PARTHENOGENESIS IN CUMINGIA 27 



abnormal except the size of the first polar body in 2 and 5. The 

 first polar body quite often divides, so that three are found (figs. 

 47 and 76). The vesicles that are formed in the egg after the 

 extrusion of the second polar body are normal and fuse to form 

 a single nucleus (figs. 76 and 77). This nucleus is decidedly 

 smaller than that formed by the fusion of vesicles from either 

 the first or the second polar spindle, but it is possible that in the 

 case figured it had not attained its full size. One could not 

 draw any conclusions from the size of the nuclei with so few 

 examples on which to base them. 



In the first cleavage of eggs with two polar bodies, one finds 

 a plate of eighteen chromosomes. These have very nearly the 

 form and size of the cleavage chromosomes in the normally 

 fertiUzed eggs, the condition being entirely different from that 

 of eggs in which maturation has been suppressed (cf. fig. 78 

 with fig. 63 and with fig. 74). 



Cleavage stages of eggs with two polar bodies are rare. Figure 

 47 illustrates a 2-cell stage, and figure 48 the only 4-cell stage 

 with two polar bodies that was found in the material. The pos- 

 sibility that an occasional one of these eggs with one or two polar 

 bodies may develop is, of course, not absolutely excluded. I 

 have found no evidence of later development among them, but 

 do not consider the study of these eggs complete. 



VII. REVIEW OF LITERATURE AND DISCUSSION 



The connection between maturation and parthenogenetic de- 

 velopment is one which has proved to be of particular interest 

 in many cases of natural parthenogenesis. Sometimes, of 

 course, the parthenogenetic egg forms both polar bodies in a 

 normal manner. In the bee, for instance (Petrunkevitch '01), 

 maturation is completed in the drone egg and development 

 begins with the reduced number of chromosomes. Petrunke- 

 vitch says that the diploid number is restored by a division of 

 the chromosomes unaccompanied by cytoplasmic cleavage. 

 According to Meves ('07), no such regulation takes place, and 

 the drone has the haploid number of chromosomes throughout 

 its development. In spermatogenesis, Meves says, there is no 



