Wolfe. — Cy to logical S Indies on Nemalion . 623 
of these phenomena as described in Nemalion , Phaseolus , and many other 
plants. 
Such nucleoli have been variously characterized as false nucleoli, 
chromatin nucleoli, or karyosomes, in contradistinction from the true 
nucleoli, or plasmosomes, which appear to contain no chromatin, and are 
supposed by some to be cast out of the nucleus at mitosis. Since, however, 
they disappear immediately before the formation of the achromatic spindle, 
they are held by other observers to be concerned in its formation. In 
general, the former have been supposed to be confined to lower plants, 
while the so-called plasmosomes were believed to be characteristic of 
vascular plants. Evidence is accumulating, however, which appears to 
indicate that even in the Phanerogams the body hitherto distinguished as 
the plasmosome is also concerned in the formation of the chromosomes, 
and suggests that further research in this direction is likely to show that 
similar conditions are, at least, of very general occurrence throughout the 
plant kingdom. The data at present available would thus seem to indicate 
that the differences existing between the various structures which in the 
nuclei of plants have been termed nucleoli are not such as would justify 
their separation under two distinct categories ; and that, although forms 
may exist which contain little or no chromatin, every gradation may be 
observed through a gradual increase of the chromatin content, to such 
conditions as are illustrated by Nemalion or Sphaeroplea , in which the 
nucleolus represents the entire chromatin content ; and therefore the 
writer would agree with Wager in the conclusion (p. 50, 1 . c.) that 
‘the nucleolus is intimately bound up with the formation of the chro- 
mosomes, and Strasburgeffs contention that it is only concerned in spindle 
or kinoplasmic formatin does not hold good, although it is not impossible 
that a portion of it — the plastin or pyrenin of Zacharias and Schwarz— 
may be used up in this way.’ 
Reduction . 
As has already been mentioned in the introduction, the primary object 
for which the present investigation was undertaken was to determine 
whether in the plant under consideration a differentiation into gametophyte 
and sporophyte could be proved, and, if so, to what extent the limits of 
these generations could be fixed by such cytological evidence as might be 
obtained. As will be seen by the following account, we may assume the 
existence of such an alternation, and hence with propriety characterize 
the period comprising the earlier divisions of the gonimoblasts as the 
sporophyte, and as the gametophyte that beginning with spore-formation 
and ending with the differentiation of the sexual elements. 
As previously stated in the description of the behaviour of the nucleo- 
lus, the number of chromatic masses appearing upon the nuclear wall in 
