794 Kemp.—On the Question of the Occurrence of 
difficult to distinguish clearly the various details ; with the aid of transverse 
and longitudinal sections, however, the following features can be made out. 
The cell walls throughout the breadth of the root are swollen and distorted, 
and the cytoplasm, particularly that of the periblem, is greatly vacuolated. 
Considerable activity is still visible, although the scarcity of nuclei in 
spireme, even in the inner cell rows, shows that it has suffered an arrest. 
The majority of the division figures occur in the densely packed cells lying 
immediately inside the endodermis. No achromatic fibres remain, and 
consequently these figures show all degrees of irregularity, the chromosomes 
at the diaster and equatorial plate stages being either crushed together 
or scattered through the cell. Here and there they are seen to be of the 
peculiar thick X-like shape which characterizes those of reproductive tissue 
(Fig. 23). The resting nuclei are granular and diffusely stained, and have 
an ill-defined membrane ; but the nucleoli contained in them have taken the 
stain intensely and are in great activity, broken up into several bodies, or 
fragmented into numerous small particles which are scattered through the 
cytoplasm (cf. Fig. 1). The droplets often to be seen in the nucleoli of normal 
roots are so pronounced as to form a conspicuous vacuolization. A peculiar 
feature is seen here and there throughout the root-tip, but occurring most fre¬ 
quently in the plerome, in cells with striking deeply stained globules of what 
appears to be nucleolar material. These globules seem to have been extruded 
from the nucleus, and are generally aggregated in one corner of the cell. The 
chromatin is granular and swollen in the spireme figures as well as in the 
diasters, and in telophase shows very imperfect separation of the two 
chromosome groups. Round such spiremes as are massed together pre¬ 
paratory to breaking up into individual chromosomes is visible the hyaline 
space so noticeable in the bean, showing where dissolution of the polar-cap 
fibres has taken place. A few binuclear cells are to be seen containing two 
nuclei of a distorted shape lying close together in the cytoplasm. 
(2) After 22 hours subsequent growth in sawdust. 
A period of 22 hours was allowed to elapse before the next fixation, in 
order that the tissue as a whole might have recovered sufficiently to offer 
figures suitable for drawing. It should be remarked, however, that in 
a fixation made after a lapse of 3 hours only, in a parallel experiment, 
the abnormalities observed were of the same nature as those to be described 
below, but the general condition of the root was bad. At the end of 22 hours 
of subsequent growth the tissue presents a clearer appearance, but there is 
still much swelling of the cell walls and vacuolization of the cytoplasm, and 
the outer cell rows are diffusely stained. The activity of division is very 
considerable, however, and many cells in mitosis are visible, in greatest 
numbers in meristem and plerome. The achromatic fibres are very imper¬ 
fect, with the result that the above figures show much irregularity, and 
