Nov., 1921] ENSIGN VEIN-ISLETS AS AN AGE DETERMINANT 439 
Table ii. Relation of Size of Vein-islets to Age in Leaves of Vitis vulpina L., Vines Q and 10 
Number 
of 
Leaves 
Vine I cm. Diameter 
(5 Annual Rings) 
Vine 4 cm. Diameter 
(15 Annual Rings) 
No. Vein-islets 
in Unit Area 
(2.25 sq. mm.) 
Area 
Vein-islets 
(sq. mm.) 
No. Vein-islets 
in Unit Area 
(2.25 sq. mm.) 
Area 
Vein-islets 
(sq. mm.) 
12 
21.8 
.1042 
25.2 
.0898 
Table 12. Relation of Size of Vein-islets to Age in Leaves of Vitis vulpina L., Vines 11 and 12 
Number 
of 
Leaves 
Vine I cm. Diameter 
(5 Annual Rings) 
Vine 6.4 cm. Diameter 
(18 Annual Rings) 
No. Vein-islets 
in Unit Area 
(2.25 sq. cm.) 
Area 
Vein-islets 
(sq. mm.) 
No. Vein-islets 
in Unit Area 
(2.25 sq. mm.) 
Area 
Vein-islets 
(sq. mm.) 
12 
17 
.1342 
18.9 
.1192 
between vein-islet area and age differences. The greatest variation was 
found in the leaves from vines 9 and 10 (table 10), where the average area 
of vein-islets showed a difference of 0.0144 sq. mm. The age difference 
here was ten years according to the number of annual rings. In contrast 
to these figures, the data in table 8 are interesting. In this case there is 
an age difference of nineteen years but a difference of but 0.0065 sq. mm. 
in the average area of vein-islets, the smaller islets being found in the 
younger plant. For a similar age difference Benedict records a difference 
in vein-islet area of 0.2553 sq. mm. 
It is interesting to make some other comparisons between the sizes of 
vein-islets as found by Benedict and those obtained by the writer from 
leaves of the same species, Vitis vulpina (table 13). Of course this com- 
Table 13. Comparison of Vein-islet Areas Obtained from Individuals of Varying Age hut of 
the Same Species ( Vitis vulpina L.) 
Benedict 
The Writer 
Number Annual 
Vein-islet 
Number Annual 
Vein-islet 
Rings 
Area (sq. mm.) 
Rings 
Area (sq. mm.) 
5 
0.4845 
5 
0.1421 
6 
0.3983 
6 
0.1740 
6 
0.3684 
6 
0.1205 
6 
0.3983 
5 
0.1042 
II 
0.3690 
12 
0.1054 
16 
0.2966 
15 
0.0898 
17 
0.3310 
17 
0.1389 
16 
0.2966 
17 
0.1389 
17 
0.3160 
18 
0.1192 
25 
0.2503 
25 
0.1270 
Average 
0.3509 
0.1260 
