‘ Heterotypical Reduction 5 in Somatic Cells. 789 
majority of the nuclei the nucleoli are broken up into two or more bodies. A 
feature peculiar to the bean is seen in such cells as contain nuclei at the late 
spireme stage; surrounding the closely coiled thread is a hyaline area 
of a curious bipolar shape, evidently representing the polar-cap fibres which 
have disappeared under the influence of the poison. These fibres in the 
normal bean are particularly conspicuous, and hence their appearance is 
more noticeable in this plant than in Galtonia. There is throughout the 
tissue a general absence of fibrillar structures, with the result that the 
dividing nuclei present very irregular figures. At the equatorial plate and 
diaster stages the chromosomes are scattered throughout the cell, and 
at the telophase are to be seen going into rest in two masses, still joined 
together by thick strands of chromatin. The chromatin, as in Galtonia , has 
a peculiar swollen appearance and is finely granular, and the chromosomes 
are somewhat shorter and thicker than in the normal root. They also 
show a marked longitudinal split. The division figures are scattered 
throughout the root-tip, although in greater numbers in the internal than in 
the external cell layers. 
2. After 22 hours subsequent growth in sawdust. 
After the lapse of 22 hours the general appearance of the tissue is more 
normal, although cell walls, cytoplasm, and nuclei still show the effects 
of the poison to a certain extent, in swelling, vacuolization, and diffuse 
staining. The chromatin itself also is still granular. The activity of 
division seems to have returned in full force, and innumerable figures of 
spireme, diaster, and telophase are to be seen throughout the breadth 
of the root, and from the extreme tip back to the permanent tissue at 
some distance from it. Figs. 8, 9, 11 show the striking modifications 
which have arisen in many of these division figures ; and also a second 
feature characteristic of the bean, namely the frequent occurrence of multi¬ 
polar divisions. Most of the latter seem to be tripolar ; they are, however, 
extremely irregular in character. The inequality in size of the chromosome 
masses at the three poles, the direction of the strands of chromatin which in 
some cases join these masses together, and also the existence of such pecu¬ 
liar figures as that shown in Fig. 8, indicate indeed that the tripolar arrange¬ 
ment must have arisen through the breaking up of the chromatin into 
unequal groups at the stage of the equatorial plate. These tripolar divisions 
have in some cases been complete, and are separated at the telophase 
by well-defined cell walls; in other cases the latter are only partially 
formed, and strands of chromatin persist here and there between the 
groups of chromosomes. Evidently resulting from these multipolar divisions 
are numerous groups of cells, generally three in number and of peculiar 
shapes. In some of these groups the cells are completely separated from 
each other, but in others imperfect dividing walls are seen, and the nuclei 
3 H 
