‘Heterotypical Reduction ’ in Somatic Cells. 783 
presents a peculiar appearance, being granular and somewhat swollen. 
Although the nuclei at the spireme stage are almost confined to the internal 
cell-rows, division figures are found here and there throughout the entire 
root-tip, in external cells, periblem, and plerome, and also at a considerable 
distance from the growing point. It is important to bear the latter detail in 
mind in considering, at the later stages of fixation, the binuclear and tetra- 
ploid cells which result from the above division figures. The fact of finding 
such cells far back in the permanent tissue does not necessarily indicate 
that they have passed over to that position from the meristem. 
3. After five hours subsequent growth over water. 
Roots fixed at this period still present as a whole a somewhat patho¬ 
logical appearance, and show a considerable degree of inactivity, the 
majority of the nuclei being in rest. At the same time these resting nuclei 
stain more sharply than did those seen at the earlier fixations, they are also 
becoming more coarsely granular and their membranes are better defined. 
Most of the stain, however, is still taken up by the nucleolus. The latter 
is very striking, being broken up into two or three deeply staining bodies, 
which often lie apart in the nucleus and appear in some cases to be thrust 
out into the cytoplasm. The external cell layers still show the fine frag¬ 
mentation of chromatin throughout the cytoplasm noted at the earlier 
fixation, but the cytoplasm itself is now less vacuolated. Although a slight 
return of fibrillation is visible in some cells, the majority of the division 
figures are very irregular, and contain no clear fibrillar or cell-plate 
structures; or at most only a faint fibrillation between the irregular masses 
of chromosomes which constitute the diaster. The equatorial plates consist 
of scattered chromosomes with widely split halves. The chromatin, particu¬ 
larly that of the telophases and diasters, is very granular, and appears 
swollen. Large numbers of cells are to be seen containing two small nuclei 
lying somewhat close together, in some cases with flattened contiguous 
sides as in those observed earlier, but in others with a rounded outline. 
4. After twenty-two hours subsequent grozvth. 
At the end of twenty-two hours’ growth the roots show a considerable 
return of their staining properties. The cell walls are clearly defined, and 
the cytoplasm even, and free from the scattered bodies described above. 
The nuclei stain sharply, and the membrane of those in rest is conspicuous. 
Division has been resumed to a considerable degree, and is taking place 
rapidly throughout the root-tip. Many nuclei are to be seen in spireme, 
in diaster, and in telophase. Few, if any, of the division figures, however, 
are normal in character, the achromatic fibrillar structures being very scanty, 
and the majority of the diasters showing imperfectly separated chromo¬ 
some-groups adhering to each other by strands of chromatin (Figs. 2 and 7). 
