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1900] THE CELL PLATE IN HIGHER PLANTS 97 
acts as a center for spindle formation. While the recent con- 
tributions on the subject of spindle formation in higher plants 
vary greatly in detail they all agree in one particular, viz., that 
the first indications of a spindle are to be found in connection 
with the nucleus and that the subsequent prophases take place 
while the fibers remain in this connection. These facts may be 
explained by the hypothesis that the nucleus is the center for 
the formation and activity of the kinoplasm. 
The further history of the equatorial zone in the onion pre- 
sents a striking difference from its history inthe larch. Whereas 
in the latter it disappears with the rearrangement and change 
in the connecting fibers prior to the formation of the cell plate, 
in the former it soon becomes filled with a substance that stains 
strongly with the orange of the triple stain. The spindle fibers 
retain their violet color in the same regions, showing that the 
orange stain is taken by a substance foreign to the fibers (figs. 
‘4,15, 28). In appearance this substance is entirely homo- 
geneous. I could detect no appearance of granules or any other 
definite structural elements in it. It would seem to be a sub- 
Stance in solution in the living cell. It is a significant fact that 
the cell walls showed the orange stain in those preparations in 
which this orange stained substance is most evident in the spindle. 
In many Preparations in which there was a slight excess of 
Violet, the cell walls were stained blue and the substance in the 
€quatorial zone could scarcely be distinguished from the sur- 
rounding blue stained protoplasm. By the use of other stains 
it was often difficult to color or differentiate this substance. In 
one preparation, stained with eosin and methyl green, in which 
the methyl green was in excess, all parts of the cell were stained 
Steen except the equatorial zone and the cell walls, both of 
which showed a slight tinge of eosin. In all of the stains used 
when both the cell wall and the interfilar substance were stained, 
nets color was the same. There were some cases, however, in 
Which the walls Were stained while the equatorial zone remained 
c . : ; . ; 
Olorless, ¢. §., slides stained in ruthenium red or iron haema- 
toxylin, 
