Nov., 1921] ENSIGN — ^ VEIN-ISLETS AS AN AGE DETERMINANT 
437 
A number of determinations made from the cleared leaves of white oak 
(Quercus alba) and of Platanus occidentalis revealed no correlation between 
the size of vein-islets and their relative ages. 
The barberry leaves studied were from plants of known age. The 
department of landscape gardening^ at Cornell University had several 
hundred one-year-old seedlings in cultivation. In several places on the 
campus, barberry plants were known to have been growing from six to 
twelve years, and were probably several years old when first planted. 
Leaves from these plants of different ages were cleared, stained, and studied 
as to venation. A summary of these determinations is presented in tables 
5 and 6. 
Table 5. Relation of Size of Vein-islets to Age in Berheris vulgaris L. 
Known Age of Plants 
I year 
6 years -|- 
.2405 
.2378 
Table 6. Relation of Size of Vein-islets to Age in Berheris TJiunhergii DC. 
Known Age of Plants 
2 years 
12 years -f 
Average Area of Vein-islets of 18 Leaves (sq. mm.) 
.2163 .2196 
The conclusions that may be drawn from these results are subject to 
two interpretations, (i) The age differences may not be sufficiently great 
to influence very materially the size of the vein-islets. Yet Benedict 
records instances in which individuals of Vifis vulpina with an age difference 
of not more than three to five years show a positive correlation. (2) It 
may be that this particular perennial does not register its relative age in 
its more or less complex nervature. Figures i and 2, Plate XXIII, show 
the nature of venation of Berheris vulgaris. 
The work up to this point was done while at Cornell in 1916-17. The 
data presented below were obtained from leaves of Vitis vulpina which 
were gathered from various places near Ithaca, New York. They were 
preserved in 85 percent alcohol in test tubes until December, 191 8, and 
were in very good condition. Because of the fact, however, that most of 
the chlorophyll had been extracted, a comparison between the sizes of 
vein-islets in cleared and uncleared material was not possible. 
The plants from which these leaves were taken were selected and marked 
in the same manner as that described by Benedict (i). The greatest care 
was taken to secure leaves for comparison that were growing under as nearly 
similar environmental conditions as possible. Data from cleared and 
stained leaves only are given in tables 7-12. The results show quite wide 
variations as to size of vein-islets in the leaves from different vines. The 
significant fact to be noted, however, is that there is no definite correlation 
2 Courtesy of Professor Hunn. 
