536 KNupDsON: CAMBIAL ACTIVITY 
OBSERVATIONS ON THE APPLE 
The methods of investigation in the apple were essentially the 
same as in grape and peach. Only one tree was used. It was 
growing on the campus at the foot of a four-foot road embankment 
The tree was about forty years old, and for several years no 
practical attention had been given it. Cuttings were removed 
from one-year-old branches, from four-year-old branches and from 
one of the main branches having a diameter of 4cm. The detailed 
data are given in TABLE III. 
TABLE III 
AVERAGE DIAMETER INCREASE IN THE APPLE 
| 
One-year-old Four-year-old Ten-year old 
thise of branches branches branches 
cutting ; ey yg a: 7 ORRIN General notes 
Xylem | Phloem | Xylem |Phloem Xylem Phloe 
pentane | ns ‘microns | 
May 8. -Peae te) | = es (0) o |Leaves 2.5X1.5 cm. Pink 
of fruit buds evident. 
He OS AO ot 20 — 123 — |Leaves 2.5X2 cm. Full 
bloom 
no OR MO to ie depo bas ae — jLeaves6.5X3cm. Fruit set 
“ 99..| 250 | 8a 157 133 205 — |Leaves 11X4 cm. Full- 
grown. Fruit 8 mm. di- 
| ameter 
June 15 287 98 | 180 | 123 | 246 | 143 |Fruit 18 mm. diameter 
“ 0 430 143 246 205 | 512 185 |Fruit 23 mm. diameter : 
“29..| 686 | 123 | 4go | 125 | 540 | 164 |Néw buds appearing. Fruit 
36 mm. diamete 
July 19 soa a 94 | 246 | 402 | 164 Fruit 37 mm. diameter 
Aug. 9 379 840 | 205 | 738 | 160 
Nov. 4..) 504 90.2 
In each case cambial activity began before May 15, but it was 
impossible to determine from the sections whether or not phloem 
formation had begun. In all cases xylem formation was completed 
by July 19 and the characteristic thickening of the cell walls was 
also practically completed. By August 9, the date of the last 
observatjons, the cambium was in its resting condition. The 
most rapid increase began just after the leaves had attained full 
size. 
INCIDENTAL OBSERVATIONS IN 1913 
Material for examination was collected in 1913 from the apple, 
peach, pear, plum, and cherry. Two apple trees were examined, 
a Baldwin and a Rhode Island Greening. The trees were about 
