j6 Blackman and Paine.—Studies in the 
These experiments suggest that the sudden cooling in itself affects the 
permeability of the tissues, but the experiments were not carried far enough 
to enable this point to be decided. The difficulty of obtaining material of 
sliced pulvini which would give quantitatively comparable results was a bar 
to more accurate work. 
Table II. 
Effect of Contraction ou the Rate of Exosmosis from the Pulvinus 
of Mimosa pudica. 
October 14, 1915. Pulvinus with sides sliced away almost to the 
vascular bundle. Temperature 39-4° C. Illuminated by Nernst lamp. 
Stimulated by touching with platinum wire. A and A' give the angles 
which the pulvinus makes with the petiole before and after stimulation. 
Time. 
Mins. 
A. 
A\ 
Gemhos. 
Rate of 
Exosmosis. 
Time. 
Mins. 
A. 
A 1 . 
Gemhos. 
Rate of 
Exosmosis. 
0 
Leaf cut 
169° 
I 5°° 
Stimulated 
11 
170° 
— 
27*8 
—- 
3i 
155° 
— 
38-0 
0.7 
12 
170° 
—■ 
28.7 
o-9 
32 
160 0 
— 
38*4 
°*4 
13 
170° 
— 
2 9'5 
c-8 
33 
164° 
— 
38-8 
0-4 
14 
170° 
— 
30-2 
07 
34 
166° 
— 
39*i 
o*3 
15 
170° 
— 
30*7 
°*5 
35 
167° 
— 
39*4 
o*3 
170° 
161 0 
Stimulated 
167° 
147° 
Stimulated 
16 
164° 
— 
31*3 
o-6 
36 
155° 
40-2 
o-8 
17 
168° 
— 
31*9 
o*6 
37 
160 0 
— 
406 
o-4 
18 
i 7 o° 
— 
32*4 
°*5 
38 
163° 
— 
41*0 
0-4 
l 9 
170 
— 
32-8 
o*4 
39 
165° 
— 
4‘*3 
o-3 
20 
170° 
— 
33*3 
o*5 
40 
166° 
— 
41-6 
o-3 
170° 
152 2 
Stimulated 
166 0 
149° 
Stimulated 
21 
L57 
337 
0-4 
4i 
154° 
— 
42-4 
o-8 
22 
—- 
— 
34* 2 
°*5 
42 
l ¥l 
— 
427 
o-3 
23 
168 0 
— 
34*5 
o*3 
43 
l6 2° 
— 
43*1 
o-4 
24 
j 7°: 
— 
34*9 
o*4 
44 
163° 
— 
43*4 
o*3 
25 
170° 
— 
35-2 
o*3 
45 
t6 4 ° 
— 
43*6 
0*2 
170° 
150° 
Stimulated 
164° 
146° 
Stimulated 
26 
157° 
35*8 
o-6 
46 
I 5°° 
— 
44*3 
o*7 
27 
163° 
— 
36*1 
o-3 
47 
155° 
— 
44*7 
0-4 
28 
— 
— 
36-7 
o*6 
48 
159 
■— 
45*i 
°*4 
29 
168 0 
— 
37'° 
o-3 
49 
162° 
— 
45*4 
°’3 
30 
169° 
— 
37-3 
o-3 
50 
163° 
— 
45-7 
°*3 
That cooling itself is not responsible for the slight increase of exosmosis 
of electrolytes associated with contraction is shown by the results given in 
Table II, where stimulation was brought about by touching the pulvinus 
with a loop of platinum wire which hung beside the pulvinus in the water 
of the conductivity cell. The pulvinus was thus kept at constant temperature; 
but the increase of exosmosis is well marked, especially in the second half 
of the table. The readings were taken every minute in this experiment, 
thus their accuracy is not very high. It is possible, though not probable, 
that part of the increase may be due to mechanical injury produced by con¬ 
tact of the wire with the tissues. The fact that most of the increase appears 
in the first minute after stimulation suggests that cell injury is not responsible 
