July, 1921] 
THE SEEDLING OF PHASEOLUS VULGARIS 
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average +.509 for primary double bundles and hypocotyledonary bundles, 
+ .629 for intercalary bundles and hypocotyledonary bundles, and +-8 13 
for total bundles and hypocotyledonary bundles. In the trimerous plants 
these correlations average +.381, +.238, and +.598, respectively. 
The correlations for normal plants are generally higher than those for 
abnormal plants. 
2. The correlation between each of the three classes of bundles at the 
base of the hypocotyl and the number of bundles in the central region of 
the epicotyl is low. The coefficients are sometimes positive and sometimes 
negative in sign. On the basis of the data available it is impossible to 
assert that there is any correlation at all between the numbers of bundles 
in these two regions. 
3. The correlation between the numbers of bundles in the central region 
of the hypocotyl and in the central region of the epicotyl is likewise very 
low. The coefficients are generally not significant in comparison with 
their probable errors. If there be any correlation at all between the numbers 
of bundles in these two regions it is very slight indeed. 
These results for correlation fully substantiate the conclusions drawn 
in an earlier paper that there is a complete reorganization of the vascular 
system at the cotyledonary node. 
4. The correlation between the number of bundles (either hypocoty- 
ledonary or epicotyledonary) in siblings is, if it exists at all, very low. The 
differentiation of the parent plants through either genetic or environmental 
factors cannot, therefore, be considered to be the source of the variation 
and correlation in bundle number demonstrated in this and in our preceding 
paper. 
Conclusions 
These results, and others for which the reader must turn back to the 
body of the paper, justify the emphasis at this point of the following general 
conclusions : 
a. The vascular structures of the seedling are not constant but are 
decidedly variable within the species. They show different degrees of 
variability within the individual organism. 
h. Seedlings differing in external form are profoundly differentiated 
in their internal anatomy. This differentiation is evident both in mean 
number of bundles and in the degree of variability in bundle number. In 
short, the external form and the internal structure of the seedling are highly 
but not perfectly correlated. 
c. The different anatomical characters of the seedling are interrelated 
with varying degrees of intensity. Between some there is a very strong 
correlation, but between others practically none at all. 
The quantitative measurement and interpretation of such relationships, 
by means of the biometric methods hitherto little applied in the field of 
vascular morphology, will make possible material advance in the investiga- 
tion of the fundamental problems of morphogenesis. 
