Harris, A quantitative study of the factors influencing etc. 
7 
be exercised in discussing, except upon a groundwork of extensive 
quantitative data, questions of the physiology of nutrition or of the 
“causes“ of the so-called “fluctutating variability“. 
The influence of position in the pod. 
The possibility of an influence of the position of the seed in 
the pod upon the weight that it attains is suggested by the general 
belief that the ovules near the ends show a higher mortality. The 
causes of this failure are quite unknown. There seems little ground 
for the assumption that the end seeds have not room to develop. 
The fact that development is not equally frequent at both ends of 
the ovary evidences strongly against this view. More probably, 
the factors are opportunity for fertilization and Variation in plastic 
materials. If distance from the stigma affects time of fertilization, 
or if distance from the pedicel influences the chances of obtaining 
seed-building substances, these factors should theoretically be re- 
corded in the weights of the seeds as well as in the relative numbers 
developing in each of the several positions. 
For the series here considered records of the position of all 
seeds developing as well as of those weighed have been kept. It 
seems worth while to consider the data. It is idle to ascertain 
the percentage of development or weight at maturity of ovules in 
any position in a sample of pods of various numbers of ovules. 
The pods must be sorted into sub-groups according to the number 
of ovules which they contain. It might be desirable to sub-sort 
the ovule classes according to the number of seeds matured per 
pod, but for our present purposes and on the basis of the available 
data this extra refinement is out of place. 
The relationship between the position of the ovule in the 
pod 1 2 ) and its chances of development is shown in the most Con¬ 
densed manner by a graph, Figure 2. 3 ) 
From this diagram, it is perfectly clear that: 
a) The chances of development are much better for ovules 
situated towards the distal than those towards the proximal end 
of the pod. 
b) For pods with a small number of ovules (three), the Po¬ 
sition of maximum development is generally at the tip, In pods 
with a larger number of ovules the rate of increase in percentage 
of development is not linear, and there may be a decided falling 
off at the distal end of the pod. 
p By “position in the pod“, we understand the serial Order from the 
proximal to the distal end — the firwt ovule being numbered 1. 
2 ) In the five diagrams, the percentage of the total ovules formed which 
develop into mature seeds in any position in the pod is shown by the heights 
of the circles on the scale indicated in part at the side of the graph. The 
position of the ovule in the pod is indicated by the shift from left to right 
on the base line. Thus, the reader, with a little trouble (unavoidable, if the 
data are to be presented in a very Condensed form) may determine with mo¬ 
derate accuracy the percentage frequency of development for any position in 
any of the chief classes of pods. 
