712 
Fritsch and Haines .— The Moisture-relations 
the contents of the plasmolysed cells all being unstained after half an hour, 
whilst the majority of the unaffected cells were stained. In later stages of 
such experiments, however, the few unaffected cells are not stained, whilst a 
certain number of the strongly plasmolysed ones are. 
Some of the drought material of Experiment XVI (cf. Table V) was 
subjected to the same treatment. The contents of all the dead cells and of 
the non-granular ones were immediately deeply stained, whilst the numerous 
cells with large irregular granules (cf. below) required but little longer to 
stain. The protoplasts of the few perfectly healthy green cells with fine 
granules, on the other hand, remained unstained, although it was very 
noticeable that in these last the wall became distinctly coloured, much more 
so than in the other cells or in the original fresh material. Similar results 
were obtained with the material that had been in a sealed slide for five days 
(cf. Table IX, Experiment XVI), the protoplasts of the majority of the cells 
being immediately stained, whilst the few healthy green cells with fine peri¬ 
pheral granules remained unstained. 
Taule XV. 
Percentages of cells 1 stained with eosin (treatment as described in text) in 
Zygogoninm during drought and subsequent recovery. 
(Experiment XXXI, habitat III.) 
Original Days of drought, 
material. ■ -- 
12345 
Series 1 
I I'O 
83-7 
99 * 1 
— 
— 
— 
>> 2 
2-5 
5-4 
5-4 
• 
CO 
99‘2 
IOO'O 
> > 3 
o-o 
15-6 
94-2 
997 
— 
— 
Days after soaking. 
2 3 5 
72*5 — 46^6 
— 9 6 '4 97 ’ 1 
83-2 — — 
There can hardly be any doubt that there is an appreciable alteration 
in the degree of permeability to eosin on the part of the cells of Zygogonium 
during a period of drought. 2 This has been established by keeping material 
over 34-5 per cent, sulphuric acid in a desiccator, in the dark and at a con¬ 
stant temperature of 18 0 C., and making daily estimations of the numbers of 
stained and unstained cells. At each estimation some of the filaments, well 
teased apart, were placed for half an hour in a watch-glass in 0-2 per cent, 
eosin in tap-water, and the material was then mounted in ordinary water. 
The results are reproduced for three separate series in Table XV. A marked 
feature of all three series is the suddenness with which the change in per- 
1 2,000 or more cells were counted at each estimation in this experiment, no dead ones being 
taken into account. 
2 I he only other explanation that could be advanced for the phenomena about to be described 
is that the increased tendency to take up the stain is due to a change in the reaction, and therefore in 
the electrical condition of the protoplasmic substance, rather than to an increased permeability. Such 
an explanation, whilst possibly applying in the case of Hormidium (cf. p. 713), is not established for 
Zygogonium by the available data. 
