A Genetic Study of Plant Height in Phaseolus Vulgaris.'] 25 
node. Usually, tho not universally, the third internode is longer 
than the second and occasionally, tho rarely, exceeds the first 
internode in length. In normal plants growing under fairly 
uniform conditions, internode length becomes increasingly greater 
from the third internode on until the maximum is reached. 
In plants of determinate growth habit (bush beans), maximum 
internode length for the main axis sometimes occurs at the fourth 
and sometimes not until the seventh or eighth internode, but, 
whatever the number, it is almost universally the terminal 
internode that is longest (Fig. 10). This statement could not 
(A) 
(B) 
(C) 
(D) 
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1 
1 
1 
1 
1 
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1 
1 
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i 
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ll 
1! 
r 
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h 
II 
1 
II 
1 
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1 
1 
1 
1 
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A 
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B 
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A' 
1 
0 2 4 
2 4 
6 
012 J 4 
10 
4 
14 
16 18 20 
10 12 14 
22 24 26 
16 18 20 
Internode numbers.! 
Fig. 11. — Growth curves of the main axis — solid lines — and of the branches — 
broken lines— of (A) a very tall bush bean, Tallbush, 3,420 G), (B) a 
medium tall bush bean, Red Marrow, 3,459 d), (C) a part of very tall pole 
bean, Fillbasket, 311 (4), (D) a very short pole bean, Snowflake, 231 (3). 
