162 BOTANICAL GAZETTE [SEPTEMBER 
formation of a complete cell plate, the original fibers mayb 
supplemented by the growth of new peripheral fibers. The cases 
in the larch in which the cell plate is not completed after the 
first nuclear division are possibly accounted for by the fact tha! 
the nucleus has begun to prepare for its second division, até 
consequently new fibers necessary for the completion of the cel 
plate are not produced. 
Concurrent with the growth of the cell plate in extentai 
the disappearance of the fibers from a central portion of the 
spindle the nuclei come to lie nearer the cell plate (figs. 4 I} 
This phenomenon has often been observed, but no adequalt | 
explanation for it has been suggested. From the appearance 
the whole cell in the larch it would seem that such a migratie? 
of the nuclei is due to the mechanical pressure of the surround 
ing cytoplasm. While some granular cytoplasm has entered th 
region occupied by the spindle during the early stages, the lates 
stages show very little addition until the cell plate 1s 
complete and all of the spindle fibers have been nearly — | 
The fibers seem to form a barrier against its ingress, rar 
forms a denser layer around the whole spindle (fig. 7) | 
possible, too, that the growth of the cell plate by the a 
previously described has displaced the cytoplasm 7 ’ 
spindle, and that such a displacement results in a greater p Ss 
upon the nuclei. ae 
The history of the carbohydrate material during ie 
of the cell plate could not be followed with certainty. pind 
that it always appears plainly in connection with — 
fibers which are forming the cell plate. In the older po age 
the cell plate, however, where the spindle fibers had © oe) 
disappeared, this substance was often indistinguishable : ae 
those cases where the cell plate was split, a young cell w f 
nearly always be detected. It did not extend, so fat ea 
be seen, the entire length of the cleft, but was only : ie 
portions (fig. 37). A peculiar case was sometimes mens 
larch, where an incomplete cell plate appeared with 2 ee 
ous cell wall formed between the halves of the older P' 
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