July, 1923] 
CURTIS — EFFECT OF RINGING A STEM 
369 
movement of nitrogen into the leaves. The small number of samples 
collected at the beginning of the experiment has not allowed for any very 
accurate determinations of the percentages of increase. Yet the evidence 
is fairly clear that the ring has not entirely prevented the upward transfer 
of nitrogen, for the leaves above a ring show an increase per unit of area, 
but this increase is very much less than that in the check leaves. It is 
interesting to note that in the one instance where a narrow strip of phloem 
had grown over the ring, thus bridging the gap, the increase in nitrogen 
Table 3. Effect of ringing on the nitrogen content of peach leaves when the ring is made after 
the leaves have formed and the shoot growth is practically completed 
Tree 
Branch 
Treatment 
Date 
Sampled 
Number of 
Leaves 
Area 
(sq. 
dec.) 
Dry 
Wt. 
(g.) 
Nitrogen 
Total 
(mg.) 
Nitrogen 
per sq. dec. 
In¬ 
crease 
per 
Unit 
Area % 
Nitrogen 
per g. 
mg. 
Rel. 
mg. 
Rel. 
A 
l' 
Check 
7/21 
10 
3.921 
2.888 
71.18 
18.2 
100 
24.6 
100 
A 
I 
Ringed 
7/19 
IO 
4.469 
3-330 
84.42 
18.9 
254 
A 
I 
Ringed 
7/21 
10 
4-592 
2-993 
80.64 
17.6 
26.9 
A 
2 
Ringed 
7/ 21 
9 
3.921 
2433 
66.78 
17.0 
27.4 
Average 
17.8 
98 
26.6 
IOI 
A 
l' 
Check (a) 
8/12 
10 
4-431 
3.207 
II6.76 
26.4 
364 
(b) 
8/12 
10 
4.560 
3.156 
II4.66 
25.I 
36.4 
Average 
25.8 
100 
42% 
364 
100 
A 
I 
^Ringed (a) 
8/12 
10 
4431 
3765 
112.16 
254 
29.8 
(b) 
8/12 
10 
4.669 
3.889 
115.08 
24.6 
29.6 
Average 
*25.0 
*97 
* 4 0% 
297 
*82 
A 
2 
Ringed (a) 
8/12 
10 
4.082 
3746 
82.88 
I9..3 
21.2 
lb) 
8/12 
10 
4.302 
3.906 
82.88 
20.3 
22.1 
Average 
19.8 
77 
H% 
21.7 
60 
A 
2' 
Check (a) 
8/27 
20 
9.011 
6-757 
246.12 
274 
36.4 
(b) 
8/27 
20 
8-753 
6.720 
241.36 
27.6 
35-9 
Average 
27.5 
100 
51% 
36.2 
100 
A 
2 
Ringed (a) 
8/27 
20 
7.637 
8.591 
164.08 
21.5 
19.1 
lb) 
8/27 
20 
7.982 
8-435 
159.60 
19.9 
18.9 
Average 
20.7 
75 
16% 
19.0 
53 
B 
i' 
Check 
7/21 
10 
4.696 
3.065 
96.18 
20.5 
3M 
2' 
Check 
7/21 
10 
4.460 
2.836 
90.30 
20.2 
31.8 
Average 
20.4 
100 
31.6 
100 
B 
I 
Ringed 
7/21 
10 
4.651 
2.875 
81.48 
17-5 
28.3 
3 
Ringed 
7/21 
10 
3-753 
2-393 
63.OO 
I6.7 
26.3 
Average 
I7.I 
84 
274 
86 
B 
3 ' 
Check (a) 
IO /7 
22 
9.7H 
6.939 
280.56 
29.4 
40.8 
(b) 
10/7 
22 
9.391 
7.270 
286.44 
30.5 
394 
Average 
29.9 
100 
46% 
40.1 
100 
B 
3 
Ringed (a) 
IO/7 
22 
7.005 
6.465 
131.04 
18.7 
20.3 
lb) 
IO/7 
22 
7.011 
6.169 
127.68 
18.2 
20.7 
Average 
18.5 
62 
8% 
20.5 
5i 
* A narrow strip of tissue had developed bridging the ring on this branch. 
27 
