796 Kemp.—On the Question of the Occurrence of 
or three. At the extreme tip of the root they are fewer in number than at 
the preceding fixation. Far back from the growing point, in the permanent 
tissue, occur much elongated cells, with two nuclei dropping against the 
wall and relapsing into inactivity. In this part of the root also are visible 
long cells, of which the nucleus is broken up into small round bodies, feebly 
stained, and evidently in process of disintegration. Degenerated masses of 
chromatin and shrivelled cell walls are to be seen here and there wedged in 
between groups of cells which are themselves frequently of peculiar shape ; 
these probably represent the disintegration of one member of a tripolar, or 
a part of a tetraploid mitosis. Fragmentation of the nucleoli is very 
noticeable. ‘ Heterotypical ’ figures are still conspicuous in many cells, but 
in others this character appears to be diminishing, and intermediate forms 
between it and the normal occur here and there. 
(4) After 60 hours subsequent growth. 
At the end of 60 hours of subsequent growth, the features presented 
by the roots are essentially the same as those described at the preceding 
fixation. Certain points of difference which require note, however, are the 
following. Although the condition of the tissue as a whole seems to have 
improved, the nuclei staining sharply, and cell walls and cytoplasm appear¬ 
ing more normal, and although many nuclei in spireme are visible, yet 
at the same time the percentage of disintegration figures has considerably 
increased, and the nucleoli also are for the most part broken up into number¬ 
less small bodies and scattered through the entire cell. These figures 
suggest the inference that the tetraploid cells are going to the wall with 
some rapidity. Another point of importance is found in the appearance of 
the * heterotypical ’ chromosomes. The gradual transition, observed at 
the preceding fixation, from the marked ‘ heterotypical ’ character of these 
to one more nearly resembling that of normal chromosomes is increasingly 
evident. Numerous cells are to be seen, best shown in transverse section, 
in which the chromosomes, although amounting to twenty-eight in number, 
are yet approximately normal in shape (Fig. 25). 
As remarked above, in the hope of inducing modifications of the 
‘ heterotypical ’ figures, by which it might be possible to detect their real 
nature, a considerable variety of experiments were carried out upon pea- 
roots. Different strengths of solution of the chloral hydrate were used, and 
longer or shorter periods of immersion. The latter varied between \ hr., 
1 hr., ij hrs., 2hrs., and two percentages of chloral hydrate were tested 
besides that in the above experiments, namely 1 % and 0-5 %. It was found 
that the effect of the poison upon the tissue as a whole varied in degree 
only, not in nature. With the 1 % solution the action was very violent, and 
great distortion of the nuclei and shrinkage of the cytoplasm resulted. 
