March. 1922J TELLEFSEN — RELATION OF AGE TO SIZE 
in discussing the collection of cuttings. As before, a tree less than 2| inches 
in diameter was considered to be in group A, one 4 to 6 inches in diameter 
in group B, and trees 8 or more inches in diameter were considered to be 
in group C. 
Table 28. Average Areas of Veiyi-islets of Leaves of Trees of Salix nigra, Group B 
Ave. Areas of 
Number of Tree 
Diameter of Tree 
20 Vein-islets 
(Inches) 
(Sq. Mm.) 
2 
4 
.261 
■2 
c 
•3^4 
6 
6 
.297 
7 
6 
.261 
9 
5 
•275 
10 
5 
•305 
18 
4 
•333 
21 
6 
.239 
28 
5 
.261 
33 
5 
•524 
36 
4-5 
.524 
47 
5 
•343 
57 
4 
.282 
59 
4 
.289 
61 
4 
•379 
64 
4 
•393 
65 
4 
.360 
66. 
5 
•379 
67 
5 
.220 
69 
5 
•323 
3281 
Table 29. Average Areas of Vein-islets of Leaves of Trees of Salix nigra, Group C 
Ave. Areas of 
Number of Tree 
Diameter of Tree 
20 Vein-islets 
(Inches) 
(Sq. Mm.) 
I 
8 
.382 
5 
. 8 
.261 
12 
10 
•244 
13 
15 
.275 
14 
•244 
15 
10 
.282 
19 
•• 13 
.289 
20 
12 
•323 
22 
8 
•330 
35 
10 
.500 
Average 
3130 
Table 30. Comparison of Average Areas of Vein-islets of the Leaves of Salix nigra 
Average Area of Vein-islets of Leaves of Trees, Group A 4369 sq. mm. 
Average Area of Vein-islets of Leaves of Trees, Group B 3281 
Average Area of Vein-islets of Leaves of Trees, Group C 3130 
About twenty leaves of average size were picked from each tree. They 
were carefully placed in envelopes each bearing the number of the tree from 
which they were collected. 
