3i6 
M. R. ENSIGN 
Table 2. Showing uniformity of vein-islet area in different regions of the same leaf {Citrus 
grandis) 
Leaf No. 
Number of v ein- 
of Leaf 
plets in 4 Sq. Mm. 
Surface 
Size of Vein-is 
lets (Sq. Mm.) 
Midrib 
Periphery 
Midrib 
Periphery 
I 
12 
12.5 
.3333 
•3250 
13 
13 
•3123 
•3123 
3 
13 
1 1 
•3123 
.3666 
A 
10 
1 1 
.4000 
5 
12 
13 
•3333 
.3123 
6 
14 
16 
.2894 
.2500 
7 
12 
13 
•3333 
.3123 
8 
13 
13 
•3123 
.3123 
9 
8 
8 
.5000 
.5000 
10 
II 
II 
.3666 
.3666 
Average 
II. 8 
12. 1 
•3492 
•3423 
Average 50 additional leaves 
10.5 
10.6 
.3809 
•3775 
Mean average 60 leaves 
10.7 
10.9 
•3756 
•3714 
Influence of an Insufficient Food Supply upon the Size of 
Vein-islets 
To some of the pots in which the Citrus seedhngs were grown, no fertihzer 
was applied. The soil was sandy and very poor in humus content. These 
plants were noticeably below the normal size of the other two-year-old 
seedlings. They were also chlorotic, and on the whole gave a very sickly, 
stunted appearance. During the course of the summer, some of these 
plants sent their roots through the drain hole in the pot and established 
themselves in the soil upon which the pots were placed. These plants at 
once responded to the effects of an adequate food supply and grew rapidly. 
The new leaves had a perfectly normal color and size, and the old leaves 
regained in part a normal color. 
Mature leaves were taken from these stunted plants and the venation 
was studied. The results are given ini table 3, where the size of the vein- 
Table 3. Influence of insufficient food supply upon size of vein-islets of leaves of Citrus 
grandis 
Plant Number (2 Leaves per Plant) 
Number of Vein-islets in 4 Sq. Mm. 
Size of Vein-is 
ets (Sq. Mm.) 
Chlorotic 
Healthy 
Chlorotic 
Healthy 
12 
10 
.3333 
.4000 
2 
13 
10.5 
.3123 
.3800 
3 
13 
10.2 
•3123 
•3956 
4 
10 
ii^5 
.4000 
•3570 
5 
12 
ii^5 
•3333 
•3333 
6 
14 
12 
.2989 
•3333 
7 
12 
12 
•3333 
•3752 
8.- 
8 
10.8 
.5000 
.3666 
9 
II 
II 
.3666 
.3800 
10 
10 
10.5 
.4000 
•3405 
Average for 10 plants 
II-5 
11.00 
•3590 
.3661 
