in Plant Cytology. 189 
period, it persists for a considerable time as a spherical blad- 
der, surrounded by a delicate protoplasmic sheath, and con- 
nected by refractive threads with the nucleolus internally, and 
by the radiating strands externally, while definite pores in it 
permit the outflow of the nucleoplasm. In other plants most 
observers describe its gradual absorption during the middle, 
or later prophase stages. This is clearly seen in dividing 
bean, corn and banana cells. The aggregating constituents 
of it, which have been stained by iron-hematoxylin and 
Bordeau red, indicate a linin and chromatin combination. In 
daughter cells which are passing from the anaphase to the 
telophase state, the nuclear membrane differentiates first round 
the outer ends of the poles, and gradually grows round the 
nuclear substance. This differentiation is contemporaneous 
with redistribution of the linin and chromatic substance, and 
reformation of the nucleolus. The recent statements by 
Wisselingh that the nuclear membrane, network, and nucleo- 
lus undergo varying degrees of corrosion, suggest specific 
physical or chemical differences, the exact value of which we 
cannot as yet estimate. 
NucLEAR SuBSTANCE.—If we exclude the nucleolus, the 
nuclear substance with its membrane make up the bulk of the 
nucleus. Many histologists now distinguish three components 
in it, the nucleoplasm, the network or linin substance, and the 
deeply-stained granules or chromatin. Appealing again to 
dividing cells, the role of events consists in the aggregation 
of refractive substance of the nuclear membrane and still 
earlier of the network, and, as is being more and more fully 
recognized, with distribution in most cells of the nucleolar 
substance. When preparations are even slightly over-stained 
the aggregating substance is uniformly dense, but a proper 
degree of staining reveals that the aggregating loops or 
threads are made up of more deeply-stained bodies, the chro- 
matin granules, as described by Debski and others, which are 
