June 15,1925 Environment and Chemical Composition of Grape Juices 1173 
medium to high total astringency, high 
astringency being due in the majority 
of cases to a high content of astringent 
nontannins. 
The remaining varieties suffered 
more or less severely from the freeze, 
they losing two to three weeks of the 
effective period for photosynthetic 
activity and their crops were reduced 
to 30 to 85 per cent of the normal. It 
is of interest to ascertain to what ex¬ 
tent the crop produced under the 
abnormal conditions tends to show the 
same correlations in composition as are 
found in other years. Summarizing 
the data, we find that 9 varieties had 
maximum, 7 next-to-maximum sugar 
content, 4 stood in third place, 9 in 
fourth place, and 10 had the minimum. 
In acid content there were no maxi¬ 
mum, 7 next-to-maximum, 17 in third 
place, 10 next-to-minimum, and 5 
minimum. In total astringency 9 had 
the maximum, 3 the minimum, and 25 
were intermediate. As regards true 
tannins, 6 had the maximum, 16 the 
minimum, and 15 were intermediate, 
while 15 had maximum nontannins and 
21 an intermediate amount, there being 
none with the minimum. The ma¬ 
jority of these varieties occupy an inter¬ 
mediate position in their sugar, acid, 
and total astringency, but there are 
some maximum and minimum results 
upon sugar. An examination of these 
in detail will constitute a rather crucial 
test of the persistence of the correla¬ 
tion found elsewhere, since the varieties 
having maximum sugar were those 
having greatest reduction in the crop 
(40 per cent or less) while those showing 
minimum sugar had 60 to 85 per cent 
of a normal crop. (See Table III.) 
Expressed in another way, plants hav¬ 
ing comparable amounts of foliage 
were storing sugar in crops of very 
unequal size; the plant with a very 
small crop brought its fruit to a high 
sugar content in the same time and 
under the same conditions that- per¬ 
mitted the plant with a crop of approxi¬ 
mately normal size to store only a 
minimum. 
Of the 9 varieties attaining maximum 
sugar content in 1921, 3 had minimum 
acid, 2 next-to-mimimum, and 4 stood 
in third place, there being no maximum 
or next-to-maximum cases. Two had 
maximum and 7 next-to-maximum as¬ 
tringency. For the varieties having 
minimum sugar content, 5 had next-to- 
maximum acidity, 3 stood in the third 
place, and 1 in fourth, while 6 had 
maximum and 3 next-to-maximum 
total astringency. Thus, nearly all 
the cases of extremes in sugar, acid, 
and total astringency are related, high 
sugar being accompanied by low acid 
and astringency and low sugar by the 
opposite condition. The remainder of 
the crop was made up of individuals 
characterized by the absence of ex¬ 
tremes in any particular, sugar, acid, 
and astringent constituents alike being 
intermediate in amount between the 
high and low figures occurring in other 
years. 
Summarizing, two outstanding con¬ 
clusions are to be deduced from the re¬ 
sults of this study. First, the amount 
of sunshine received during the period 
March 1 to September 30, inclusive, is, 
for the five years of this study, a de¬ 
pendable index of the sugar content of 
the crop of grapes produced by a large 
number of varieties each of which was 
bearing annual crops of average or nor¬ 
mal size. Under the conditions of the 
experiment, the amount of sunshine 
received during the growing season is 
the only climatic factor which varied 
widely from year to year, hence it de¬ 
termined the amount of photosyn¬ 
thetic product accumulated in the crop. 
While there are individual exceptions, 
the majority of varieties behave quite 
uniformly as one throughout the experi¬ 
mental period. 
Second, there is a consistent and 
fairly high degree of correlation be¬ 
tween sugar, acid, and total astringent 
content, extending through the experi¬ 
mental period. The nature of this 
relationship is such that a high con¬ 
tent of sugar is found associated with 
low or medium content of acid and of 
astringent constituents, a low content 
of sugar is associated with high acidity, 
and astringency, while an absence of 
extremely high or low sugar content is 
accompanied by an absence of ex¬ 
tremes in acid and astringency. While 
there are some exceptions, this general 
statement holds not only for four years 
of normal crops but also for a year in 
which frost injury materially reduced 
the crop. In every year there is an 
evident mass tendency to behave in the 
manner stated. 
The explanation of this situation would 
appear to be that the content of each of 
these constituents present in the grape at 
maturity is conditioned by the amount 
of sunlight received by the plant during 
the formation of the crop. Conditions 
which favor a maximum accumulation 
of the products of photosynthesis in the 
fruit also favor the reduction of the con¬ 
tent of acid and astringent constituents 
to a low or minimum point. Condi¬ 
tions which minimize photosynthetic 
activity depress the accumulation of 
sugar in the fruit to a minimum and at 
the same time depress the reduction of 
