934 M. M. Mercaur 
longitudinal direction, yet they are always connected by transverse 
fibrils (Fig. 50). The general form of the group of fibres is spindle- 
shaped, it being thickest at the equator of the nucleus, where it 
bulges out almost or quite to the nuclear membrane. As the chief 
chromatic fibres converge toward the two poles of the nucleus they 
frequently, one can say usually, bend inward toward the axis of 
the nucleus, presenting a peculiar and very characteristic appearance 
of a spindle with acuminate ends. 
Centrosomes. 
There are no centrosomes visible either inside or outside the 
nucleus.!) The thick chromatic fibres extend to and are in contact 
with the nuclear membrane at the poles of the nucleus (Figs. 51, 55. 
Pl. XVIII). Usually these fibres are somewhat swollen at or near 
their ends, forming granules of quite noticeable size (Figs. 51, 57, 
Pl. XVII}. There are no special aggregations of achromatic material, 
either granular or fibrous, at the poles of the nucleus. None of the 
structures found can be interpreted as a centrosome. 
Equatorial plate stage. 
These is no well defined equatorial plate stage in the mitosis. 
The chromatin masses make an irregular group scattered through 
the whole equatorial third of the nucleus (Figs. 45—48, Pl. XVIII). 
There is at this time no indication of any longitudinal splitting of 
the chromosome masses. If it occurs at all, it has occurred previous 
to this stage. 
Anaphases. 
This very irregular and imperfect equatorial plate stage soon 
passes into an early anaphase condition in which one sees the 
chromatin masses arranged in two transverse rows (Figs. 49—52, 
Pl. XVIII). These masses are still united one to another by the 
longitudinal fibrils and one often finds this connection so definite as 
to suggest that the masses so united in pairs are products of a 
transverse division of the chromatin masses of an earlier stage. 
Probably some have recently divided, but others divide at a con- 
siderably earlier stage, before the spindle is formed. Some of the 
1) Of. Prrrznzer (1886), Ténnices (1899), Liczr & Dusosce (1904b) and 
NERESHEIMER (1907). 
