14 
I made four sets of experiments, with essentially the same results; here 
it will suffice to give one of these. 
This set was begun on January 11 and weighing commenced on Jan- 
uary 13; but this beginning was made abortive by a rain which flooded 
the whole site. A new start was made on January 17. The weights 
given here are in centigrams, and are the average absorption for each day 
comprised in the interval ending at the date at the top of the column: 
Root No. Jan, 20. Jan. 23. Jan.27. | Jan.31. Feb.3. | Feb. 10. | Mar. 1, 
| | | | | 
| | | 
I | 6 | 6 6 7 7 3 "| 
r 15 6 15 19 | 19 14| 12 
I | 19 | 8 a6 11 14 bo2 | 28 
IV 8 8 2 3 9 8 7 
V “16 18 28 35 | 43 43 | (3) 
VI 7 11 10 | b3 3 3 6 
Vil 248 47 52 | 58 | 40 439 | 39 
Vill 6 7 8 9 15 7 8 
IX 3 2 6 6 5 » ( hoeaecateniae 
Be 41 33] $39 | 39 49 3617 
| | 1 
aPneumathodes appeared. 
> apparently dead of ying. 
‘Cap sloughed (absorption greater than figures show), 
The root V was injured February 10, and was then cut with a sharp 
knife without exposing the surface to the air, and the cut surface was 
then immersed just as the uninjured tip had previously been; the total 
subsequent absorption was only 63 centigrams. I had already satisfied 
myself that practically no water can be absorbed by cut leaves, and the 
same disadvantage from the experimenter’s standpoint is presented by the 
roots. It is of interest to note that while an open wound is very promptly 
plugged, dead tips maintain their full absorbing activity for a considerable 
length of time. 
From these results I do not believe accurate conclusions can be drawn 
as to the total absorption by an entire tree. The very great diversity in 
the rapidity of absorption by the roots is but one of the reasons for this. 
From a considerable number of measurements on different roots I can 
say that, as a general average, the end of a main root, which, on anatom- 
ical grounds, appears to be in a condition to absorb water, has about one- 
sixth of the total surface possessed by all the root tips tributary to it. 
If absorption were proportional to the exposure of living epidermis, then 
the most rapid rate exhibited by any of these roots would indicate a total 
daily absorption by a large tree of only about 24 liters. But there is no 
such correlation between living epidermis and absorption, as is shown 
by the behavior of dead roots and by the two mentioned in the preceding 
table, the growth of which was temporarily most conspicuously rapid. 
The immediate result of the rapid growth was a long zone of young tissue, — 
but in one of these cases the ensuing absorption was remarkably slow. 
eT ee 
