412 KING. [VoLt. XIX. 
from the time that they are first formed by the breaking of the 
spireme (Fig. 33) up to the stage when the germinal vesicle 
disintegrates in preparation for the maturation mitosis. At 
the time that the spireme divides longitudinally (Figs. 28-29) 
the chromatin filaments are found to be composed of a series 
of rounded granules from which a few fine fibres project on 
either side. When the spireme breaks into chromosomes the 
number of fine projections increases, evidently at the expense 
of the chromatin granules (Figs. 33, 34, 36). By the time 
that the odcyte has reached the stage of Fig. 39, the appear- 
ance of the chromosomes has changed considerably. The 
axial portion of the thread is now composed of minute, faintly 
staining granules, evidently formed by the breaking up of 
the larger ones, and the fine projections from the sides are 
longer and more numerous than at an earlier period. The 
chromosomes, of which there are undoubtedly twenty-four, 
thus come to have the feathery appearance that characterizes 
them from this time until the beginning of the maturation 
period, and they greatly resemble the filamentous chromo- 
somes found by Rickert (76, 77) in the selachian egg and by 
Born in the egg of Triton. After the stage of Fig.. 39 the 
chromosomes stain very faintly, since the greater part of their 
substance seems to be in the form of fine fibres as it was 
during the synizesis period; they can always be found, how- 
ever, if the egg has been properly preserved and stained. When 
the germinal vesicle is about to disintegrate the chromosomes 
lose their filamentous structure and become greatly condensed, 
appearing as a single series of perfectly round granules (King, 
49; Fig. 8). . 
The arrangement of the chromosomes in the young oocyte 
depends, evidently, on the extent to which sister portions of 
the spireme have separated before the spireme breaks into seg- 
ments. The transverse division of a spireme like that shown 
in Figs. 31 and 32 produces chromosomes that are scattered 
irregularly throughout the nucleus and only occasionally 
paired; while the division of a spireme similar to that shown 
in Fig. 30, gives a paired arrangement of all of the chromo- 
