127 
Acer negundo , L. y and Staphylea trifolia , Z. 
means the case. The members of the bivalents take the form of short 
lumps. The rods which are fastened to the spindle fibres at one end may 
lie parallel with the spindle axis or at right angles to it. A glance at 
Fig. 39 will show how, in polar view, one member of a bivalent may obscure 
or partly conceal a neighbouring bivalent, and if, as almost always happens, 
the two halves of a bivalent do not lie closely applied to each other, each 
half may appear as a whole chromosome. Likewise the close arrangement 
of the segments as they pass to the poles is also an element to interfere 
with strict accuracy in counting. A comparison of Figs. 35 and 37 with 
Fig. 39 shows that a very marked condensation has taken place in the 
chromosomes. At the spindle stage the difference in size among chromo- 
somes is less than at previous stages. 
A phenomenon worthy of note at the stages in question is seen in the 
zone of larger granules formed about the nucleus, and which later surrounds 
the spindle (Figs. 35, 39, and 40). At the stage of the loose, hollow spireme 
the cytoplasm is uniformly granular, with very small nucleolar-like bodies 
scattered throughout the cell, and later, as the chromosomes approach the 
poles, the cytoplasm presents again a more uniform appearance in regard 
to the distribution of granules upon its network. To these granules may 
be applied Strasburger’s term ‘ trophoplasm ’, but in so doing the writer does 
not intend to convey the idea that trophoplasm is necessarily alveolar in 
structure. In pollen mother-cells these granules do not represent alveolae 
at all. They are merely amorphous particles held within the cytoplasmic 
network. In Fig. 33 we have this somewhat uniformly appearing cyto- 
plasmic network with the granules more evenly distributed, while in Figs. 35 
and 39 there is present the same character of network, but the granules are 
more numerous in circumscribed areas. It may be true that more of these 
granules are present, but whether the granular matter has increased in 
quantity, or has merely become collected into the region in question from 
other parts of the cell, may be left an open question. In the spindle stage 
there appear also groups of globules in the cytoplasm lying in a plane with 
the nuclear plate (Figs. 39 and 40). These globules are not extra-nuclear 
nucleoli, but oil-drops which turn black with osmic acid, and from which 
the dark colour may be readily removed by hydrogen peroxide. The 
peculiarity about these globules is the position they occupy in the cell. 
Later they may disappear entirely (Fig. 41). 
The large nucleolus which is present at the stage of complete segmen- 
tation of the spireme into the chromosomes (Figs. 35, 38) has disappeared 
by the time the spindle is mature, and at this stage and during the anaphase 
the amount of nucleolar material demonstrable as extra-nuclear nucleoli is 
very meagre. It is perfectly clear that the nucleolar matter is not taken up 
by the chromosomes, because the latter undergo a very considerable diminu- 
tion of size, presumably by a process of condensation, during the disappear- 
