76 J. H. Priestley and Dorothy Armstead 
Table III values are given for the change in sugar content in two 
successive fractions of liquid drawn through the same stem, and in 
the cases numbered 3, 4 and 5 this equilibrium condition is approxi¬ 
mately reached. 
Table III 
Stems of Acer pseudoplatanus L. irrigated, liquid collected in two 
successive fractions A and B 
Cane 
sugar Absolute Gain or loss 
Dura 
ition 
Volume 
Volume 
after 
amount 
A 
Irrigating 
irri¬ 
liquid 
liquid 
irri¬ 
cane 
Absolute 
Condition 
solution 
gation 
through 
lost 
gation 
sugar 
0 / 
/o 
amount 
hrs. 
c.c. 
c.c. 
0/ 
/o 
gm. 
gm. 
1. In bud 
Distilled 
| A 
2 
62 
10 
0-12* 
0-07 
+ 0-12* 
+0-07* 
water 
1 B 
48 
— 
0-025 
O'OOI 
+ 0-025 
+0-001 
2. In bud 
0-17 % cane 
| A 
2$ 
25 
25 
0*12 
0-03 
—0-05 
—0-013 
sugar 
1b 
1* 
20 
~ 8 
0-095 
0*019 
-0-075 
—0-015 
3. In bud 
o* 17 % cane 
(A 
4 & 
3 
14 
0-15 
0-005 
— 0-02 
—0-0006 
sugar 
]B 
i6| 
3 
— 
0-15 
0-005 
— 0'02 
—0-0006 
4. Leaves 
o* 17 % cane 
JA 
2* 
73 
4 
0'24 
0-18 
+0-07 
+0-05 
just out 
sugar 
IB 
2i 
22 
— 
0-12 
0-03 
—0-05 
—o-oi 
5. Leaves 
o* 16 % cane 
[A 
2* 
12 
8 
0*20 
0-024 
+0-04 
+0-005 
just out 
sugar 
(B 
2* 
15 
— 
O'll 
0'02 
—0-05 
—0-008 
* In this one case a slight trace of hexose sugars was detected in the liquid. 
This conception could be utilised to analyse the differences in sap 
between trees in different developmental stages, for instance, trees 
in bud, with buds bursting, in leaf, etc. Dixon and Atkins (i) ( loc . 
cit. p. 195) have found that the sap ascending in the xylem is most 
concentrated just as the leaf buds are bursting. The experiments 
recorded in Table III also support this conclusion, thus numbers 4 
and 5, where the leaves are just opening, are the only stems giving 
out sugar into the sugar solution passed through them. 
Curtis (8) has recently described some experiments in which he 
has ringed the phloem at two levels on the same stem and studied 
the subsequent fate of the starch reserves between these two rings. 
He regards this observation as strong evidence for his view, elabo¬ 
rated in this and in a subsequent paper ( 9 ), that the xylem stream is 
not responsible for any appreciable transfer of carbohydrates from 
root to stem or from one region of the stem to another. Evidence 
obtained in this manner, however, could not destroy the cogency of 
such evidence as that summarised by Atkin or that presented above, 
which deals with the analysis of sap moving in the xylem strands. 
It is also clear that the non-removal of starch from the region 
between the two rings in Curtis’ experiments might be due to the 
fact that the sap traversing the xylem between the two rings was in 
