546 
HERBERT C. HANSON 
Table 3 
Green Weight, Dry Weight and Water Content of Leaves from the Center and South Peri- 
phery of Isolated Trees, and from the Base and Apex of Forest Trees 
Green Weight 
Dry Weight 
Water Con 
tent 
Position 
of Tree 
Crams 
Grams 
Crams 
<7 of 
% of 
per Sq. 
% 
per Sq. 
% 
per Sq. 
Gieen 

Dcm. 
Dcm. 
Dcm. 
Wt. 
Wt^ 
Acer saccharum (isolated). . . . 
Center. . 
0.835 
46 
0.354 
38 
0.481 
74-6 
135-9 
So. Per.. 
1.760 
100 
0.937 
100 
0.823 
52.1 
87.9 
Acer saccharum (forest) 
Base. . . . 
0.878 
47 
0.361 
35 
0.517 
58.8 
143.2 
Apex . . . 
1.882 
100 
1.029 
100 
0.853 
45-4 
82.9 
Tilia americana (isolated) . . . 
Center. . 
1.078 
58 
0.038 
51 
0.698 
64.8 
183.7 
So. Per.. 
1. 861 
100 
0.745 
100 
1. 116 
59-9 
149.8 
* Tilia americana (forest). . . . 
Base. . . . 
0.745 
29 
0.223 
20 
0.522 
70.1 
234.1 
Apex . . . 
2.589 
100 
1. 114 
100 
1-475 
56.9 
132.4 
Quercus alba (forest) 
Base. . . . 
1-354 
74 
0.817 
70 
0.537 
39.7 
65-7 
Apex . . . 
1.825 
100 
I-I73 
100 
0.652 
35-7 
55.6 
* Quercus alba (forest) 
Base. . . . 
1.276 
58 
0.467 
47 
0.809 
63-4 
173.2 
Apex . . . 
2.186 
100 
0.997 
100 
1. 189 
54-4 
119. 2 
Quercus rubra (forest) 
Base. . . . 
1.458 
63 
0.699 
58 
0.759 
52.1 
108.5 
Apex . . . 
2.331 
100 
1. 190 
100 
1. 141 
48.9 
95.9 
Quercus macrocarpa 
Center. . 
1.469 
66 
0.579 
46 
0.890 
60.7 
153-8 
(isolated) 
So. Per.. 
2.227 
100 
1.272 
100 
0.955 
42.9 
75-1 
Ulmus americana (isolated) . . 
Center. . 
0.906 
71 
0.309 
55 
0.597 
65-9 
193.2 
So. Per.. 
1.274 
100 
0.560 
100 
0.714 
56.0 
127.5 
Fraxinus pennsylvanica 
Center. . 
1.428 
59 
0.467 
29 
0.961 
67.3 
205.8 
(isolated) 
So. Per.. 
2.440 
100 
1.639 
100 
0.801 
32.8 
48.8 
Acer saccharinum (isolated). . 
Center. . 
0.723 
60 
0.229 
42 
0.494 
68.3 
215.9 
So. Per.. 
1.211 
100 
0.546 
100 
0.665 
54-9 
121. 8 
* Second growth leaves of the season. 
1. 1 14 g., A. saccharum 1.029 g., Ulmus americana 0.560 g., A. sac- 
charinum 0.546 g. The relation of this sequence to tolerance is note- 
worthy. The green weights of the leaves from the same position do 
not show so much relationship, but Fraxinus, Q. rubra and Q. macro- 
carpa weighed most, while Ulmus and A. saccharinum weighed least. 
Two crops of leaves were produced by many trees during the 
growing season of 1915. The first crop appeared under cold and 
humid conditions. The second crop developed about June 25 when 
the warmer and drier summer weather had arrived. In the latter 
part of August the first crop of leaves showed a much lower water 
content than the second crop. The total green weight of the base 
leaves of the second crop was less and of the apex leaves greater than 
that of the first crop. The explanation of this probably is that the 
new base leaves were developed under lower light intensity caused by 
the shade of the first leaves; while the new apex leaves appeared when 
