648 
Report of a Discussion on 
Strasburger’s experiments to present sufficient data in themselves to 
solve the problem. I think it will presently be seen that in this 
view Professor Askenasy was mistaken ; meanwhile I may remark 
that Professor Askenasy himself appears to have changed his opinion 
upon this point, as in his second paper 1 (April, 1896) he appears 
before us actively engaged upon experiments similar to, and having 
the same teaching as, some of our earlier ones. 
The leading idea of our theory suggested itself to us at an early stage 
in our investigation. The following difficulties naturally presented 
themselves : — 
(1) Is water containing air in solution and under such tension as 
must obtain in high trees (according to this hypothesis) stable ? 
(2) Will this stability also exist in presence of wetted wood? 
(3) Is the leaf capable of exerting such a lifting force as will suffice 
to raise the column of water in high trees ? 
Of these questions, the first had previously only been quite inade- 
quately considered, observers treating the presence of dissolved gas 
as detrimental to success in experiments on the behaviour of liquids 
in tension ; the second, so far as I am aware, had never been previously 
considered, nor had the third received any attention. These questions 
are obviously inseparably connected with the admissibility of the 
theory, and admit of being answered only by experiment. Their 
consideration occupy a large part of our paper as published, and 
(over and above experimental work relating to the consideration of 
other hypotheses, most of which was excised from our paper) called 
for many months of careful investigation. 
We, on our part, conceived of our theory quite originally, being 
unaware of any suggestion even remotely resembling our explana- 
tion of the cause of the ascent of sap in high trees. In this 
connexion I gladly repeat our expression of indebtedness to Pro- 
fessor Fitz-Gerald for many valuable suggestions in the course of 
our investigations. 
Lest I be misunderstood I will state definitely that in this matter 
I have no cause of complaint whatever against Professor Askenasy. 
It is, indeed, only fair to quote his full acknowledgment. A few 
lines from his second paper will suffice : — ‘ As I have remarked in my 
first paper, Dixon and Joly are the first who have clearly recognized 
1 Beitrage zur Erklarung der Saftsteigens, Heidelberg, 1896. 
