322 
M. R. ENSIGN 
plant yielding the seed is not known, it is possible that the difference between 
parent and seedling is not great enough to be measurable by this test. (2) 
The venation character may not be an indication of age differences in this 
species. 
Table 6. Size of vein-islets in leaves from polyemhryonic seedlings of Citrus grandis 
Leaf No. 
Number of Vein-islets 
in 4 Sq. Mm. 
Plant A 
Plant B 
Size of Vein-islets 
(Sq. Mm.) 
Plant A 
Plant £ 
Ave. 1st pair plants. 
Ave. 2d pair plants , 
Ave. 3d pair plants 
Ave. 4th pair plants 
Ave, 5th pair plants . 
10 
10.5 
10.8 
10 
II-5 
10.56 
137 
14 
13-5 
II. 7 
11.5 
12.88 
13 
13.7 
10 
II-5 
12.05 
10 
8.8 
10.2 
II 
10 
10.2 
10.2 
9.8 
II 
II 
10.8 
10.56 
9.2 
10.2 
II 
II 
10.04 
10.5 
14 
12 
13-7 
II 
12.24 
13 
15.8 
14 
13 
10 
13.16 
10.2 
10.7 
9.8 
10 
II 
10.34 
10 
10 
11.8 
II 
10.2 
10.60 
4000 
3800 
3750 
4000 
3499 
3809 
3040 
2894 
2955 
3500 
3499 
3177 
3123 
2999 
4000 
3499 
•3405 
.4000 
.4605 
.3920 
.3666 
.4000 
.4038 
.3920 
.4270 
.3666 
.3666 
•3741 
.3852 
•4431 
.3920 
.3666 
.3666 
.4605 
•4057 
.3820 
.2894 
•3333 
•3050 
.3666 
.3352 
•3123 
•2558 
.2894 
.4000 
.4000 
.3315 
.3820 
•3750 
.4160 
.4000 
.3666 
.3879 
.4000 
.4000 
.3400 
.3666 
.3920 
•3797 
Mean ave. for 25 leaves — 5 pairs of plants . 
11.29 
II. 15 
■3655 
.3680 
Mean ave. for 100 leaves— 25 pairs of plants. . 
II.O 
.3624 
.3666 
The reasons that may be advanced in favor of these suggestions are: 
I. The grapefruit was not grown in Florida on an extensive commercial 
scale prior to the big freeze of 1894.^ At most, then, the bearing trees are 
probably not more than twenty-five years old. Hence the gametic seedlings, 
which are assumed to be rejuvenated, may not be far enough removed in 
age from the apogamous seedlings, which are senile to the same degree as 
the parent, to show a measurable difference in the size of vein-islets. 
3 Bailey, L. H., Encyc. Hort. 2: 782. 
