440 
Vines. — The Suction-force of 
following record from the bare herbaceous stem, about 2 ft. 
long : — 
June 17, 3.50 p.m. 
4 
5 >> 
Indicator = o in. 
__ i 
>3 — 2 33 
— tI 
33 x 2 S3 
33 = 2 33 
June 18, 9 a.m. 
10 „ 
11 „ 
Noon 
2 p.m. 
Indicator = 7f in. 
33 = 7 l 33 
33 = 7 33 
33 == 7 33 
33 = 7 33 
whence it appears that, in the Beech and the Sunflower at 
any rate, air cannot penetrate centripetally into the vascular 
tissues of the plant by means of open wounds at the surface. 
This I found to be true also of the Yew. 
But to return to the question of the relation between leaf- 
area and suction-force. From the foregoing figures it would 
appear that the suction-force of a shoot is not immediately 
dependent upon the leaf-area ; and in fact the case of Heli- 
anthus indicates that an herbaceous stem deprived of its leaves 
can develope almost as high a suction-force as when the 
leaves are present. Nor does it appear that the maximum 
tension is always attained more rapidly with a larger than 
with a smaller number of leaves. Considering the foregoing 
data from this point of view we get the following results 
No. of leaves. 
Max. tension. 
Time 
required. 
1150 
2 1 2 in. 
35 minutes 
820 
20 „ 
55 
>> 
Beech. 
j 
550 
M 
00 
N>l« 
i °5 
79 
Shoot A. 
355 
20 „ 
55 
99 
2 45 
I8J „ 
no 
99 
k leafless stem 
4 l 33 
160 
99 
I 
320 
I 3 | 3, 
210 
99 
Shoot B. { 
239 
33 
39 ° 
99 
43 
52 33 
70 
99 
I 
755 
T 52 33 
90 
99 
Shoot C. J 
355 
1 H „ 
40 
99 
143 
I 52 33 
45 
99 
1 
61 
I6J „ 
220 
99 
Shoot D. j 
594 
23 33 
270 
99 
344 
33 
37 ° 
99 
Results of a similar kind were afforded by the Yew. 
A branch (4 ft. long ; diam. cut surface = \ in.) gave (July 3-4) 
