1174 
Journal of Agricultural Research 
Vol. XXX, No. 12 
acidity and astringency, leaving these 
constituents at a high level. Inter¬ 
mediate conditions result in the pro¬ 
duction of a crop characterized by the 
general absence of extremes in the 
amount of any of these constituents. 
There are occasional exceptions to each 
of these statements to be found in the 
data, but there is a clear general ten¬ 
dency to behave in the manner indi¬ 
cated. 
There is no immediate or rigid rela¬ 
tionship between acid content and total 
astringency as regards their behavior 
under a given condition; both react in 
the same direction but in varying de¬ 
gree. The same statement holds for 
the gelatin-precipitable and nontannin 
constituents grouped together as total 
astringent substances. The amounts 
of tannin and nontannins present fluc¬ 
tuate rather widely from year to year, 
and these fluctuations are to a consid¬ 
erable degree independent, and in con¬ 
sequence there are a number of cases in 
which total astringency content does 
not fulfill expectation for the reason 
that the two constituents did not be¬ 
have in the same way. A general ten¬ 
dency is clear, however, and it is possi¬ 
ble that the accumulation of more data, 
together with the extension of our 
knowledge as to the real nature of the 
substances at present grouped under 
the designation astringent nontannins, 
would furnish an explanation of the 
inconsistencies in behavior here re¬ 
ported. 
It would seem in the light of the re¬ 
sults given here that the climatic condi¬ 
tions during the growing period of the 
grape crop, or more specifically the 
amount of sunshine received, when 
other conditions are constant, bear such 
a relation to the chemical character of 
the crop that the general chemical 
character of the crop may be predicted 
from a knowledge of the effective period 
of photosynthetic activity. 
SUMMARY 
Chemical analyses of the juices of a 
collection of 66 varieties of grapes 
grown together under controlled con¬ 
ditions at Vineland, N. J., were made an¬ 
nually during the five-year period 1919 
to 1923, inclusive. The determina¬ 
tions made included total solids, free 
reducing sugars, total sugars after in¬ 
version, titratable acidity, total as¬ 
tringency, and nontannin astringency. 
The range of variation in composi¬ 
tion of the juice of any variety grown 
under constant conditions in one 
locality through a series of years is 
much narrower than the variation 
encountered when a large number of 
samples of a given variety grown over a 
wide area and under a variety of 
cultural conditions are compared. 
Differences of soil and cultural con¬ 
ditions appear to affect varietal com¬ 
position more profoundly than do 
variations in environmental conditions 
encountered over a series of years in 
one location. 
Cane sugar is of widespread but very 
irregular occurrence in the varieties of 
grapes here studied, having been 
found at least as a trace in all but one 
variety. Its presence is in some degree 
indicative of immaturity of the fruit, 
but it is often found in fully mature or 
overripe grapes. Its presence can not 
be definitely correlated with any other 
factor such as temperature, insolation, 
water supply, or load of fruit borne by 
the vine. 
There is a very definite and clearly 
marked effect of climatic conditions 
during the growing season upon the 
total sugar content, total astringency, 
and titratable acidity of the fruit 
produced during that year. This effect 
is a mass effect, all the varieties re¬ 
sponding to a given set of climatic 
conditions in the same manner. 
Of the various climatic factors enter¬ 
ing into the composition of the seasonal 
conditions at Vineland, the amount of 
sunshine received during the period 
March to September, inclusive, is 
subject to the greatest annual varia¬ 
tions and is the dominant factor in 
determining the chemical character of 
the crop. 
Under the conditions prevailing at 
Vineland, the content of sugar, acid, 
and astringent substances present in 
the juices of fully ripened grapes from 
normally loaded vines seems to be 
determined very largely if not al-, 
together by the number of days of 
sunshine occurring in the period of 214 
days between March 1 and Sep¬ 
tember 30. 
In vines bearing annual crops of 
comparable size, the year of maximum 
sunshine during the period March to 
September, inclusive, was the year of 
maximum or next-to-maximum sugar 
content of juice in a majority of all 
varieties. The year of minimum sun¬ 
shine for the period March to Septem¬ 
ber, inclusive, was the year of minimum 
or next-to-minimum sugar content for a 
majority of all varieties in which the 
vines bore normal crops. Years having 
amounts of sunshine intermediate be¬ 
tween these extremes during the grow¬ 
ing period have amounts of sugar inter¬ 
mediate between the extremes and pro¬ 
portional to the amount of sunshine re¬ 
ceived. 
