632 Report of a Discussion on 
We may pass over the cloud which arose to witness for and against 
these theories, and proceed at once to Strasburger’s great work 1 , 
in which, with wonderful courage and with the industry of genius, he 
set himself to work out the problem de novo , both anatomically and 
physiologically. In my opinion it is difficult to praise too highly this 
great effort of Strasburger’s. 
Strasburger’s general conclusion is now well known. He convinced 
himself that liquid can be raised to heights greater than that of the 
barometric column, in cut stems, in which the living elements have been 
killed. Therefore, the cause of the rise could not be (1) barometric 
pressure, (2) nor root pressure, (3) nor could it be due to the action 
of the living elements of the wood. His conclusions may be stated as 
follows : — 
( a ) The ascent of water is not dependent on living elements, but 
is a purely physical phenomenon. 
(b) None of the physical explanations hitherto made are sufficient 
to account for the facts. 
Strasburger has been most unjustly depreciated, because his book 
ends in this confession of ignorance. I do not share such a view. 
I think to establish such distinct, though negative, conclusions would 
be, in this most nebulous of subjects, an advance of great value. 
Whether he has established these conclusions must of course be a matter 
of opinion. To discuss them both would be to go over 500 pages 
of Strasburger’s book, and will not here be attempted. Conclusion 
( a ) that the ascent is not dependent on living elements must, however 
briefly, be discussed, because it is here that the roads divide. If we 
agree with Strasburger, we know that we must seek along the physical 
line ; if we differ from him, we are bound to seek for the missing 
evidence of the action of the living elements. 
Schwendener s Criticism . — Perhaps the best plan will be to consider 
the most serious criticism that has been published of Strasburger’s 
work, namely, Schwendener’s paper ‘ Zur Kritik ’ &c. 2 
Schwendener objects that although a continuous column of water 
cannot be raised by air pressure to a greater height than that of the 
barometric column, yet when broken into a number of columns, as in 
the case of a Jamin chain, that a column considerably over 10 m., even 
as much as 13 or 14 m., of water can be suspended. This, though 
1 Leitungsbahnen, 1891. 
2 K. Preuss. Akad. 1892, p. 91 1. 
