634 
Report of a Discussion on 
ii cm.; Betula , 12 cm.; Quercus, 57 cm.; Robinia, 69 cm. These 
facts seem impossible to reconcile with Schwendener’s views. 
Action of the Poisonous Fluids in Strasburger s Experiments. — The 
question whether the living elements are killed in Strasburger s 
experiments is of primary importance in the problem. 
Schwendener does not criticize it at length ; he seems to assume 1 — 
as far as I can understand — that since the death of the tissues extends 
gradually from the cut end upwards, there are living cells in the upper 
part which may still be effective. He also doubts ‘ whether the cells 
were always killed at once/ The first objection of Schwendener’s 
may or may not be sound, but in any case it does not (as Strasburger 
points out) account for the experiment 2 in which an oak stem was 
poisoned by picric acid, and three days afterwards was placed in 
fuchsin-picric. The second reagent had to travel in tissues already 
killed with picric acid, yet a height of 22 m. was reached. 
The question whether the reagents kill the cells in Strasburger’s 
experiments does not lend itself to discussion. It is difficult to see 
how they should escape, and we have Strasburger’s direct statement 
that the living tissues were visibly killed. It must not be forgotten 
that in some of his experiments the death of the tissues was produced 
by prolonged boiling, not by poisons 3 . Thus the lower 12 m. of 
a Wistaria stem were killed in this way, yet liquid was sucked up 
to a height of 108 cm. In the Histolog. Beitr. v. p. 64, he has repeated 
his air-pump experiment, using a boiled Yew branch, and found that 
eosin was sucked up from a vessel in which almost complete vacuum 
was established, so that the action of living elements and of atmospheric 
pressure was excluded. 
On the whole, the balance of evidence is, in my judgment, against 
the belief that the living elements are necessary for the rise of water. 
In other words, I think we should be justified, from Strasburger’s 
work, in seeking the cause of ascent in the action of purely physical 
laws. 
Strasburger s general argument from the structure of wood. — It seems 
sometimes to be forgotten that, apart from the physiological or experi- 
mental evidence, there is another line of argument founded on the 
structure of wood. Strasburger’s unrivalled knowledge allows him to 
1 Zur Kritik, loc. cit., 1892, p. 935. 
3 Leitungsbahnen, p. 646. 
2 Hist. Beitr. v. p. 12. 
