A GeneticlStudy of Plant Height in Phaseolus Vulgaris. 39 
Evidently the tall bush bean not only possessed potentially the 
character of long internodes but was able to impress that charac- 
ter upon its Fi progeny when crossed with a pole bean, whereby 
the partially inhibitory action of determinate growth was re- 
moved. 
It is plain from this that we cannot compare the average 
length of the few internodes of bush beans with that of the 
many internodes of pole beans. In order, therefore, that pole 
and bush beans may be directly compared, it is necessary to limit 
consideration to a definite number of internodes common to both 
tjrpes. All of the bush-bean races and crosses included in this 
study had a mean number of internodes between five and six. 
Since, if the comparison were between the first six internodes, 
a considerable number of bush plants would have to be discarded, 
only the first five internodes are here considered. For this com- 
parison all internodes above the fifth in both pole and bush plants 
have been disregarded and all bush plants with less than five 
internodes have been discarded. 
Even when consideration is limited thus to a definite small 
number of internodes, direct comparisons are not entirely trust- 
worthy. For instance, July is a pole bean of vigorous growth and 
therefore of relatively long internodes, while Snowflake is a 
slow growing pole bean and consequently has comparatively 
short internodes, but the mean length of the first three internodes 
of Snowfiake is greater than that of the corresponding internodes 
of July. Thus for 78 plants of Snowflake and 83 plants of July, 
grown side by side in the garden in 1912, the mean lengths in 
millimeters of the individual internodes from 1 to 15 inclusive 
were: 
Internode No . . . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 
July 19 14 23 41 56 78 115 122 120 120 134 140 139 138 135 
Snowflake 26 17 20 24 25 28 38 45 53 62 73 82 84 77 63 
The mean internode lengths in millimeters of these same plants 
as calculated at the end of any internode from 1 to 15 were, there- 
fore, approximately: 
Internode No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 
July 19 17 19 24 31 39 49 58 65 71 77 82 86 90 93 
Snowflake 26 22 21 22 22 23 25 28 31 34 37 41 44 47 48 
Difference -7 -5 -2 2 9 16 24 30 34 37 40 41 42 43 45 
The difference between these two races in mean internode length 
is thus seen to change rapidly up to about the eighth internode 
and much less rapidly from there on. This is indicated even 
more clearly by means of the ratios of the internode lengths of the 
two races as calculated at the end of each internode from 1 to 15. 
