104 
OTIS F. CURTIS 
Table 3, Pyrus malus {Northern Spy). Rings made 15 cm. from tip in present year's 
growth. Measurements from last hud scale scar to tip. June 11 to June jo, 
IQ18. All growth was practically completed by June jo 
I 
Not Ringed. Leaves 
Rir 
ged. Leaves 
3 
Not Ringed. Leaves 
4 
Ringed. Leaves 
Remaining 
Remaining 
Removed 
Removed 
Length 
Length 
Gain in 
Length 
Length 
Gain in 
Length 
Length 
Gain in 
Length 
Length 
Gain in 
in Cm. 
in Cm, 
Cm. 
in Cm. 
in Cm. 
Cm. 
in Cm. 
in Cm. 
Cm. 
in Cm. 
in Cm. 
Cm. 
June II 
June 30 
June II 
June 30 
June II 
June 30 
June II 
June 30 
a. . . . 
26.2 
30-5 
4-3 
24-5 
30.0 
5-5 
23.0 
25-5 
2.5 
23.3 
23.0 
0.0 
b.... 
26.0 
29.5 
3-5 
17-5 
22.0 
4-5 
24.8 
28.0 
3-2 
21.5 
21.0 
0.0 
c . . . . 
26.5 
32.5 
6.0 
23-5 
Broken 
19-5 
,23-5 
4-5 
24-5 
25.0 
0.5 
d.... 
25.0 
29-5 
4.5 
20.0 
24-5 
4-5 
23-3 
28.0 
4-7 
22.5 
23.0 
0.5 
e. . . . 
20.7 
22.0 
1-3 
26.5 
32.5 
6.0 
24.0 
24.5 
0.5 
22.4 
24.5 
O.I 
/.... 
33-0 
7-3 
23.0 
29.0 
6.0 
22.2 
27.0 
4.8 
24.6 
25.0 
0.4 
Ave. 
4.48 
1 
5-3 
3-37 
0.25 
It is to be noted in this case that the ringed twigs which retained their 
leaves made a growth greater than did similar twigs not ringed. This 
difference is not striking, but in only one pair (/) is there greater growth of 
the stem not ringed. It would seem that food manufactured by the leaves 
was beginning to be removed downward and that the ring had checked 
this removal, thus increasing the supply for continued apical growth. The 
final cessation of growth of all twigs is evidently brought about by conditions 
correlated with the rest period which will not be discussed here. The 
almost complete lack of growth of the ringed twigs that had been deprived 
of their leaves coincides with the similar results obtained with Philadelphus. 
Evidently ringing has entirely prevented the upward translocation of some 
material or materials necessary for growth. 
Further experiments of the same nature were tried with Ligustrum 
ovalifolium Hassk. Sone of the results obtained are presented in table 4. 
Other experiments showed results practically identical with these, so it is 
hardly necessary to present all of them. 
From these experiments it seems very clear that the ringing has pre- 
vented the upward movement of some substance or substances necessary 
for growth. When leaves are present above a ring, these produce enough of 
this substance to allow for continued growth. Evidently the check in 
growth is not due to lack of water resulting from injury to the xylem, for 
those stems that were ringed but retained their leaves always made fair 
growth, which occasionally even exceeded that of the checks. Under 
certain conditions, however, ringing does seem to be followed by withering 
of the parts above the ring. This occurs especially when the ring is fairly 
near the young tip but only when no leaves are left above the ring. Hanstein 
(i860) obtained similar results and concluded that lack of water cannot be 
the cause of the withering, for when leaves remain above the ring, certainly 
more, water is necessary but growth continues, while the shorter the part 
above the ring the less water it will need but the quicker is its death, even 
in a moist atmosphere. 
