52 FARR: QUADRIPARTITION IN SISYRINCHIUM 
is accomplished by equatorial plates on the spindles. Quadri- 
partition by cell-plates has never been satisfactorially described 
and figured in any of the higher plants in connection with a 
study employing modern methods of microtechnique; it is there- 
fore much to be desired that the authors present these instances 
in detail as soon as possible. 
Florin (7) in 1918 found that quadripartition occurs in the 
spore-formation of one of the acrogynous Jungermanniales but 
does not give the details of the process as to whether it is by 
furrowing or cell-plates. In 1919, Miss Digby (3) published 
an extensive chromosomal study of Osmunda in which she refers 
to the formation of cell-plates after the first reduction division. 
These apparently persist through the second mitosis without 
forming completed partitions, and then other cell-plates are 
formed at right angles to these. The figures of these stages 
are drawn from material of O. palustris var. aurea although the 
description seems to apply to all four of the types studied, 
including O. regalis. Smith (20) in 1900 described and figured 
these stages of the latter species. He concluded that the cell- 
plate of the first division was ephemeral and that the division 
was finally accomplished by the simultaneous formation of six. 
cell-plates on the six spindles respectively, thus accomplishing 
quadripartition by cell-plates. During 1920 Yamaha (27) pub- 
lished a study of cell-plate formation in the archesporial and 
spore-mother-cells of Psilotum triquetrum. He found that the 
nearly complete cell-plate which is formed after the first meiotic 
division breaks up into a granular mass, which persists until 
the close of the second nuclear division. At this time it becomes 
transformed into connecting fibers upon which a cell-plate is laid 
down between the non-sister nuclei, while other cell-plates are 
being formed on the connecting fibers between the sister nuclei 
of the second division. In this way a quadripartition of the 
cell is accomplished by cell-plates. Yamaha concludes that the 
cell-plate has a duplex nature from the first, and that it does not 
split after formation as Timberlake believed. It is to be noted 
that in quadripartition by furrowing the partition is duplex from 
the first. Yamaha suggests that the invagination of the plasma- 
membrane may play some part in the later stages in these cells 
of Psilotum. It therefore seems to me that on account of this 
duplex nature of the partition and in the light of the recent work 
on quadriparition by furrowing that further work on cell-div- 
ision of Psilotum would be warranted. 
