534 KNUDSON: CAMBIAL ACTIVITY 
internodes. The material was fixed in Gilson’s solution, imbedded 
in celloidin, and later sectioned and stained. On the same days 
that material was collected, observations were taken on the ex- 
ternal manifestations of growth in order that the formation of 
xylem and phloem could be correlated with the growth of leaves, 
elongation of new shoot, and development of fruit. 
In Taste I are given the data on the growth-measurements in 
the grape. 
TABLE I 
DIAMETER INCREASE OF PHLOEM AND XYLEM IN ONE-YEAR-OLD SHOOTS OF THE GRAPE 
Num- Diameter | Increase | Increase 
ber of Date of branch, | of Laven of phloem, Leaf, fruit, and shoot development 
cutting mm, ms | icrons 
| 
4 | May 8 3-5 ee] o  |Buds swelling 
12 e 4.75 cy) | o |Largest leaf 2 mm. wide 
25 ay 6 oO 0 shoot 30 cm. long. Largest 
be . wide. Fruit-bud 
| cluster 3 cm. lon 
46 Oats ee 102 61 |Leaf 16X16 cm. New shoot 60 
| cm. long. Fruit-bud cluster 
6-8 cm. long, not gs sai 
44 June 9 4.75 o | 0 Lauber leaves 18 X18 New 
shoot 86 cm. Breibod clus- 
o | “fh cm. long; some open 
94 15 5 143 | 73 |Leaf 20X19 cm. New shoot 96 
Tendril developing 
illary ips 12 cm. long, with 
leaves c oa ruit 
set. Only occasional stamens 
= to be se 
#0 20 aie 102 71 |Leaf 20 cm. broad. New shoot 
oe Too cm. pod size of peas 
144 29 6.5 486 | 222 |Leaf20X20cm. New shoot 155 
= lew ish of. — (largest) 
Dreregt 
168 | July 19 1,000 {| 445 New dhbct 195c¢ 
185 | Aug. 9 980 | 405 early ie ein: 16 mm. 
diameter 
fot Oe Fs 729 | 405 
Diameter increase began simultaneously in both phloem and 
xylem. The cambial activity began between May 23 and May 29, 
at which time the leaves were almost completely developed. 
Cambial activity ceased before August 9, for at this time the new 
xylem and the new phloem were completely differentiated and the 
cambium was in the resting condition. Between July 19 and 
August 19 a periderm layer was produced, cutting off the old 
phloem from the new. At the base of the new shoot, at about the 
same time, a periderm layer developed just outside the phloem, 
cutting off the entire cortex. 
