292 
OTIS F. CURTIS 
stems which retain their leaves is nearly as great as that of the normal 
stems. Even the results of the 1918 experiment with Philadelphus are not 
in opposition to the hypothesis that a large part of the food used for con- 
tinued growth of a stem is produced by the leaves of that stem, for, as indi- 
cated in table 5 and also in the more detailed tables i and 2 of the previous 
paper, only about one third of the current year's growth was above the ring 
in the 191 8 experiment and this part carried only the younger leaves, while 
in the 191 9 experiment the entire new shoot with all its leaves was above 
the ring. The fact that the stems which were defoliated for a distance of 
from 15 to 20 centimeters from the tips in 191 8 (group 3) showed such good 
Table 5. Experiment to determine how much food used in shoot growth may he produced 
hy the leaves of that shoot. 
Not Ringed, 
Leaves Remain- 
ing 
2 
Ringed, Leaves 
Remaining 
3 
Not Ringed, 
Leaves Removed 
4 
Ringed, Leaves 
Removed 
Original 
Length 
of Shoot 
Gain in 
Cm. 
Original 
Length 
Above 
Ring, 
Cm. 
Gain in 
Lm. 
Original 
Length 
of Part 
Defoli- 
ated 
Gain in 
Cm. 
Original 
Length 
Above 
Ring 
Gain in 
Cm. 
Apple. June 11 to June 30. 
Ave. of 6 stems 
25.0 
4.48 
15.0 
5-3 
15.0 
3-37 
15.0 
0.25 
Ligustrum ovalifolium. June 18 to 
July 3- 
13.61 
21.7 
14.61 
22.0 
7.41 
21.7 
0.71 
Ligustrum ovalifolium. June 19 to 
July 3. 
Ave. of 6 stems 
12.41 
20.8 
10.58 
20.9 
5.75 
21. 1 
0.23 
Ligustrum ovalifolium. July 6 to 
July 22. 
Ave. of 6 stems 
12.23 
II.8 
7.2 
10.9 
7.62 
II.8 
0.28 
Ligustrum ovalifolium. July 11 to 
July 22. 
Ave. of 25 stems 
9-94 
17.8 
8.19 
Philadelphus pubescens. May 30 
to June 8, 1918. Rings in 
new growth. 
Ave. of 5 stems 
54-6 
34-1 
17.0 
11.75 
17.0 
27.0 
17.0 
0.5 
Philadelphus pubescens. May 30 
to June 4, 1919. Rings in old 
wood below base of new growth 
18.8 
16.36 
21. 1 
12.96 
17.4 
7.96 
18.5 
1. 16 
Philadelphus pubescens. June 3 to 
June 6, 1919. Rings in old 
wood below base of new 
growth. 
Ave. of 8 stems 
37-6 
9.38 
38.4 
7.13 
40.0 
3-56 
30.8 
1.44 
growth, while the shoots of the 191 9 experiment (group 3) showed such 
poor growth gives additional proof that the leaves of the new shoot supply a 
large part of the food used in growth after a few leaves have once opened. 
In 191 8 that food was available which was produced by the many leaves on 
the lower non-defoliated part of the stem, while in 191 9 only stored food 
was available as the entire new shoot was defoliated. 
