ARTIFICIAL PARTHENOGENESIS IN CUMINGIA 19 



sponding to that of the fertihzed one shown in figure 3. More 

 chromosomes are drawn in figure 53 than in the corresponding 

 figure of the normal egg, owing to the fact that in the latter case 

 the section did not contain the whole of the spindle, but as far 

 as the form and size of the chromosomes go the two are alike. 

 The important difference is that, while the outer pole of the 

 spindle in the fertilized egg Hes in a cytoplasmic bud, there is 

 no sign of any such bud in the parthenogenetic egg. In this, 

 as in the later stages, the whole spindle lies within the circum- 

 ference of the egg. 



The transformation of the anaphase groups of chromosomes 

 into resting nuclei is like the telophase of any division except for 

 the absence of cytoplasmic cleavage. The chromosomes break 

 up into a mass of chromatin at each pole of the spindle, as is 

 shown in figure 54. Here we have also a third mass, half-way 

 between the poles, which was doubtless formed from a few 

 lagging chromosomes. Then follows the formation of numerous 

 small vesicles and the gradual fading of the achromatic figure 

 (fig. 55). The small vesicles fuse and enlarge (fig. 56) till finally 

 two resting nuclei are formed such as are shown in figure 57. 

 Sometimes a third small vesicle is found, half-way between the 

 two large ones. This represents, of course, chromosomes which 

 have not gone to either pole of the spindle (fig. 54) but such a 

 vesicle always fuses sooner or later with one of the large ones. 



The nuclei thus formed enlarge considerably, come to lie close 

 together, and eventually fuse (fig. 58, 59 and 60). The stages 

 resemble very closely the fusion of the pronuclei in a normally 

 fertilized egg, except for the fact that no aster is present in them 

 (cf. figs. 58 to 60 with figs. 10 and 11). The nuclei which rep- 

 resent the first polar body and the secondary oocyte nucleus are 

 about the size of the male and female pronuclei, and the product 

 of their fusion looks much Hke a normal cleavage nucleus. It 

 is, of course, hke the normal cleavage nucleus in being the re- 

 sult of the fusion of two nuclei, each of which contained the 

 haploid number of chromosomes. The egg is fertihzed by the 

 first polar body instead of by the sperm, and contains the full 

 amount of chromatin that was present in the primary oocyte. 



