Voi,. 7, 1921 
BOTANY: HARRIS AND SINNOTT 
39 
same (external) morphological type is in agreement with those obtained 
by a comparison of seedlings which are externally dimerous and trimerous, 
since the latter frequently have a larger number of primary double bundles 
but a smaller number of intercalary bundles than the former. In both 
types of seedlings variation in the number of intercalary bundles is the 
primary factor in determining variation in the total number of bundles at 
the base of the hypocotyl. 
Turning to the problem of the interrelationship of bundle number at 
different levels in the seedling we find that there is a substantial correla- 
90 
80 
70 
60 
SO 
40 
30 
20 \- 
10 
12 13 14 IS 16 17 18 19 20 21 
= TR/ME7iOU$ 
12 13 14 IS 16 17 18 19 20 21 
DIAGRAM 3 
Percentage frequency distributions of total bundle number in the central region of the 
epicotyl of dimerous and trimerous seedlings of two lines. Abscissae represent 
bundle numbers, ordinates represent percentage frequencies. 
tion between the numbers of the three classes of bundles — primary double 
bundles, intercalary bundles, and total bundles — at the base of the hypo- 
cotyl and the number of bundles in the central region of the hypocotyl. 
In the normal seedlings the coefficients average +0.509 for number of 
primary double bundles and number of hypocotyledonary bundles, +0.629 
for intercalary bundles and hypocotyledonary bundles, and +0.813 for 
total bundles and hypocotyledonary bundles. In the trimerous plants 
these correlations average +0.381, +0.238 and +0.598, respectively. 
The correlations for normal plantlets are practically without exception 
higher than those for abnormal seedlings. 
The correlations between the number of bundles in the hypocotyl 
(both basal region and central region) on the one hand and the number of 
