356 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8, 
in which the differences between the coefficients for the two classes of plants 
are shown. 
The differences in this table are generally negative, thus indicating that 
the correlations are lower in the trimerous than in the dimerous seedlings. 
The exceptions are of some interest. 
-o 
^ ' *0 // 12 13 14 IS 16 n IS 1$ 20 21 22 
FP/COTVL 
Diagram 8. Regression of number of bundles in central region of hypocotyl on 
number of bundles in central region of epicotyl. Empirical means represented by solid 
dots for dimerous seedlings and by circles for trimerous seedlings. 
There are only 4 exceptions among the 15 correlations between the 
numbers of vascular elements in the basal region of the hypocotyl and 
in the central region of the hypocotyl, as shown in the upper section of the 
table. These are without exception insignificant in comparison with their 
probable errors. There are 9 exceptions among the 20 correlations be- 
