300 



Harris M. Benedict 



reasonable doubt that the size of the vein islets is governed by some 

 internal characteristic of the plant as a whole. 



The way seems clear, therefore, to investigate the size of the vein islets 

 as a possible indication of the age of the whole plant. 



COMPARISON OF THE SIZE OF VEIN ISLETS IN PLANTS OF DIFFERENT AGES, 



IN VITIS VULPINA 



For the purpose of determining whether the size of the vein islets of 

 Vitis vulpina is dependent on the age of the whole plant, two methods 

 of comparison were used: (1) a comparison of the size of vein islets 

 in the leaves of these paired vines of different ages which were found 

 growing under nearly identical external conditions; (2) a comparison of 

 the size of the vein islets in the leaves borne by cuttings of vines of different 

 ages which were grown under identical conditions in soil, in nutrient 

 solutions, and in distilled water. 



' In addition to Vitis vulpina, Vitis bicolor Le Conte and a number of 

 trees were investigated to a limited extent in regard to a possible relation 

 between venation and age. The data on these latter are presented sub- 

 sequently. 



Size of vein islets of plants grown under field conditions 

 In the folloT\nng tables (from table 6 to table 20) there are presented 

 data on the vein islet measurements for each of ten leaves of each paired 

 vine. In each table the average of the vein islet measurements for each 

 of the paired vines is also given. The areas and weights of each leaf 

 are shown. The age of the vine is indicated by the diameter of the main 

 stem and by the number of annual rings. 



TABLE 6. Area of Vein Islets in Leaves of Vines 1 and 2 



Number of leaf 



Length 



(centimeters) 



Breadth 

 (centimeters) 



Area 



(square 



centimeters) 



Weight 

 (grams) 



Area of 



islets 



(square 



millimeters) 



Vine 1, 7.6 centimeters in diameter, 28 annual rings 



151 2.5 



140 2.1 



207 3.6 



161 3.1 



13 



16 



14 



15 



15 



19 



15 



16 



0.2013 

 0.2112 



0.2157 

 0.2050 



