442 Vines . — The Suction-force of 
accumulation of gas. It was then dismounted, and placed with 
its cut end in the copper-solution for forty-eight hours (till June 
29). On this date the leaves were discoloured and shrivelled : 
the shoot was then placed in connexion with the apparatus, 
and after a prolonged experiment (9.50 a. m. -4.45 p.m.) a 
maximum tension of 45 in. was registered. In a subsequent 
experiment (July 2-3) with the same branch, after all the 
leaves had been removed, the maximum tension observed 
was qj in. Again, a vigorous shoot (D) of Helianthus gave 
(July 19-20) a maximum tension of 9 J in. : it was then 
injected for twenty-four hours with copper sulphate solution, 
when it became discoloured and flaccid and gave a maximum 
tension of 5 in. Hence it appears that the suction-force of 
a dead shoot is very much less than that of a living one ; 
and more especially that dead leaves contribute but little to 
the development of suction-force in a shoot, a result which is 
confirmatory of conclusions recently arrived at by Dixon 1 . 
When, however, the suction-force of living and dead leafless 
branches is compared, the difference is less considerable ; in 
one case the difference was in favour of the presumably dead 
branch. The following are illustrative experiments : — 
Taxus (Shoot B ). 
a. Bare branch after injection with water (24 hours) : — 
July 7, 9.30 a.m.-July 8, 9.30 a.m— Max. tension=i6| in. 
b. Same branch after standing in and injection with CuS 0 4 solution (80 hours): — 
July 11, 7.45 p.m.-July 15, 10 a.m. — Max. tension = 19 in. 
Taxus (Shoot C). 
a. Bare branch after injection with water (16 hours) : — 
July 28, 9.15 a.m. -3 p.m. — Max. tension = 9 in. 
b. Same branch after injection with CuS 0 4 (16 hours) : — 
July 29, 9.30 a.m.-4-3o p.m. — Max. tension — 7f in. 
Helianthus (Shoot C). 
a. Leafy shoot injected with water (1 2 hours) : — 
July 18, 9.30 a.m.--6.30 p.m. — Max. tension = 8J in. 
b. Same shoot, deprive'd of leaves, injected with water (14 hours) : — 
July 19, 11 a.rm-7.30 p.m. — Max. tension = in. 
1 Note on the role of Osmosis in Transpiration ; Proc. Roy. Irish Acad., Ill, 
No. 5, 1896, p. 767. 
