THE OVUM OF THE NINE-BANDED ARMADILLO. IIQ 



avidity, the latter being easily recognizable from the former by 

 its greater size and vesicular character. 



In follicular stages 8 and 9 the nucleus assumes the character 

 shown in Figs. 260, and b, two sections through the same nucleus. 

 Here the entire chromatin complex has undergone further con- 

 densation until each element is in the form of a double chromo- 

 some more or less clearly defined. There is a strong tendency, 

 often much more clearly manifest than the illustration would 

 indicate, for the larger chromatin elements to aggregate into a 

 dense central mass and for the smaller elements, which are 

 frequently single spherical bodies, to lie in contact with the 

 nuclear membrane. A few of these small peripheral elements are 

 noted to be connected by linin threads with the large chromo- 

 somes forming the central group. It is not possible to enumerate 

 the chromosomes at this time, but a number of fairly accurate 

 approximations have been made which would indicate that there 

 are about sixteen large chromosomes besides a varying number of 

 small peripheral elements. These bodies may be supernumerary 

 chromosomes which subsequently either attach themselves to the 

 large elements or are thrown out into the cytoplasm on the rupture 

 or dissolution of the nuclear membrane. There are seldom any 

 evidences of small chromosomes in the spindles during the actual 

 maturation process, but partially formed spindles, as that shown 

 in Fig. 29, show certain small elements attached to spindle fibers 

 which may be homologized with the small peripheral chromatin 

 elemencs of the stage of nuclear development under consideration. 

 The plasmosome is no longer to be identified with certainty. 

 In Fig. 26b is seen a large body of diploid form which stains less 

 deeply than do ^he other chromosomes. This may be a stage in 

 the transformation of the plasmosome into a chromosome, but 

 of this I cannot be certain. In none of the nuclei examined 

 have I seen indications of the dissolution of the plasmosome and 

 am inclined to the view that it is the equivalent of a hetero- 

 chromosome. Another point which is obvious in the figures is 

 the increasing irregularity of the nuclear membrane. It is 

 evidently becoming very thin and is losing its turgor, as the 

 wrinkles in its surface indicate. This could hardly be due to 

 shrinkage in fixation, for the nuclei of earlier stages retain their 



