1170 
Jour nal of Agricultural Research 
Vol. XXX, No. 12 
efficiency of various selected stations 
for growth of soy beans (variety 
Peking) was determined by growing 
the plants for four weeks from seed 
under controlled conditions and deter¬ 
mining stem height, leaf area, and dry 
weight of tops. Hildebrandt has shown 
that there is no very close agreement 
between the instrumental measure¬ 
ments of the climatic data and the 
actual growth of the plants, the growth 
in some cases being greater, in others 
less, than expectation based upon 
climatic data. This study approaches 
the same general problem from a dif¬ 
ferent angle, in that the plant employed 
is a long-lived perennial, and the 
climatic conditions are those of a single 
locality and did not vary widely 
enough to affect the annual growth or 
fruitfulness of the plants but only 
enough to alter the chemical composi¬ 
tion of the fruit. It seems logical to 
assume that the automatic integration 
of the environmental complex by a 
perennial plant will be reflected in the 
chemical composition of the ripe fruit 
as truly as it is in the elongation and 
increase in dry weight of an annual. 
If this assumption be true, it re¬ 
mains to be determined whether it is 
possible, by examination of the or¬ 
dinary weather records of temperature, 
humidity, sunlight, and rainfall, to 
reach a dependable conclusion as to the 
nature of the effects which a particular 
set of seasonal conditions will have 
upon the composition of the crop. 
These factors are so intimately inter¬ 
related that even under the most com¬ 
plete control of experimental con¬ 
ditions thus far attained, it is difficult 
or impossible to modify the amount of 
sunlight received by a plant without 
modifying temperature and humidity. 
With plants growing in the open the 
mass effect of this interplay of factors 
is observed, but an attempt to analyze 
the result or determine the relative 
importance of the roles played by the 
individual factors is usually considered 
unpromising. There is a possibility, 
however, that the interrelationship of 
these factors is of such a nature that 
they operate together to favor or de¬ 
press photosynthetic activity in the 
plant. Thus excessive and long-con¬ 
tinued rainfall is associated with 
decreased sunlight and lowered tem¬ 
perature, ail of which operate together 
to depress the rate of photosynthesis, 
while drought implies maximum sun¬ 
light and high temperatures, which 
increase the rate so long as the plant 
has available an adequate water sup¬ 
ply. Of course extreme modification 
of any factor may result in disturbance 
of metabolism and death, but within 
the limits of normal plant behavior 
seasonal changes consist in the modi¬ 
fication of several or all the factors 
named in mass fashion, in a direction 
favorable or unfavorable to the plant. 
If this interlocking of climatic factors 
is sufficiently intimate and constant 
within the range of conditions in which 
normal growth is possible, it should be 
possible to find among the environ¬ 
mental factors some one which can 
readily be accurately measured and 
which will give a dependable indication 
of the direction in which all the factors 
have operated upon the plant during 
the season. 
Under the conditions prevailing at 
Vineland the sunlight received during 
the growing period is such a factor. 
It is the factor which varies most 
widely from year to year. The near¬ 
ness of the locality to the ocean renders 
it subject to fogs and periods of 
cloudiness and rain which extend over 
a very limited area and which cut off 
sunlight with much less accompanying 
depression of temperature than occurs 
during general rain over a wide area. 
Nearness to the ocean is also respon¬ 
sible for the absence of large differences 
in relative humidity and in tem¬ 
perature when the records of a number 
of seasons are compared. The equal¬ 
izing effect of the ocean upon these 
factors throws the variable factors, 
rainfall and sunlight, into stronger 
relief than might be the case far 
inland. 
Under these conditions there is a 
quite constant agreement between the 
sunlight received by the vines during 
the season and the composition of 
the crop. This of course does not 
mean that sunlight is the sole sig¬ 
nificant factor in determining the 
chemical composition of the crop but 
merely that in the locality of Vineland 
it is the dominant factor, other climatic 
factors playing subordinate parts and 
exerting their effects in the same 
direction. Whether there is such a 
correlation in regions remote from 
large bodies of water can be deter¬ 
mined only by future work. 
It is scarcely possible that the 
variations in "amount and distribution 
of rainfall during the period exerted 
any direct effect upon the composition 
of the crop. The period as a whole 
was one of subnormal rainfall, the 
accumulated shortage for the years 
1917 to 1923 inclusive being 15.76 
inches, although one year (1919), had 
an excess of 12.61 inches. At no 
time during the period did the vines 
display evidences of distress from a 
shortage of water, although other 
crops suffered severely from drought 
in 1921, when there was a deficiency 
of 10.07 inches. As the vegetative 
