22 1 
X-rays on Plant Cells. 
It will be seen that considerable changes took place in the circulatory 
rates of the controls during the time of the experiments, but in every case 
the irradiated specimen ultimately showed a depression in rate compared 
with its control. Precisely analogous results will be shown later in a section 
dealing with the action of radium on the same material. The effects do not 
agree with the observation of Lopriore that circulation became normal after 
cessation of treatment. 
Circulatory Rate and Influence of X-Rays. 
Coolidge tube. Heating current 3-5 amps. 
Cover-slips 0-035 cm - thickness. 
Specimens mounted in tap water. 
Slide placed at aperture of box enclosing the tube, darkened except for glow of the bulb. 
Date 
Time 
Control. 
Specimen. 
Time 
Control. 
Spe> 
:imen. 
of 
of 
Milli- 
No. of 
Average 
No. of Average 
between 
No. of 
A verage 
No. of 
Average 
ex¬ 
ex¬ 
ammeter 
read¬ 
time 
read¬ 
time 
observa¬ 
read¬ 
time 
read¬ 
time 
posure. 
posure. 
reading. 
ings. 
20 div. 
ings. 
20 div. 
tions. 
ings. 
20 div. 
ings. 
20 div. 
1922. 
min. 
milliamp. 
secs. 
secs. 
hrs. 
secs. 
secs. 
r eb. 1 
10 
1 
16 
19-1 
1 6 
20-1 
24 
16 
18.1 
16 
2 7-3 
r eb. 15 
0 
o-6 
16 
22-1 
16 
i8-i 
24 
16 
25.1 
16 
26-9 
dar. 1 
0 
o-6 
16 
I 8.1 
16 
x 3*9 
24 
16 
16.4 
16 
217 
*Iar. 23 
5 
0-2 
16 
I9.9 
16 
x 7 
24 
16 
16-3 
16 
16-9 
As treatment was extended beyond the time needed to accelerate the 
circulation other changes occurred. The protoplasm began to leave the cell 
wall, very gradually at first. In the early stages of this change the proto¬ 
plasmic surfaces were parts of smooth curves and the clear appearance was 
retained. 
To test whether this shrinkage was of reversible nature treatment was 
stopped in some cases and camera lucida drawings made of representative 
cells. The material was then transferred to a fresh supply of tap water and 
drawings made at intervals with the same focusing arrangements. The 
area of the protoplasm in these cells was estimated with a planimeter. Not 
only was there no return to the normal condition, but shrinkage was found 
to be progressive more than an hour after treatment. 
In specimens in which the shrinkage stage had been reached it was 
noticed that the pink colour possessed by some of the cells was beginning 
to fade. A possible explanation of both shrinkage and loss of colour was 
to assume the permeability had been modified and that solutions were 
escaping from the cell, so lessening the sap pressure. 
To test the truth of this assumption experiments were made upon 
pieces of epidermis torn from the under surface of the leaves of the plants. 
One strip from each leaf was exposed and the other kept in tap water as 
a control. 
Immediately after exposure to the Coolidge tube the specimens were 
