16 BULLETIN 335, TJ. S- DEPARTMENT OF AGRICULTURE. 
Particular attention is called to the data on sugar and acids. 
The Catawba crop studied in 1911 was harvested October 1 to 4, 
and though certain plants were held and sampling was continued 
25 days longer, the results show only a gain of 1.22 grams of sugar 
and the loss of 0.24 gram of acid in 100 cc of juice. The apparent 
increase of sugar was doubtless due to evaporation of water from 
the berries and the loss of acid is possibly accounted for in the loss 
of malic acid. This would probably have disappeared in wine 
fermentation, 1 giving practically the same or a lower result than that 
recorded for the last sample. It is certain that nothing would have 
been gained for commercial purposes by holding this particular 
crop on the vine after the date it was harvested. 
It is not to be understood that the dates of full-crop ripeness 
given in the tables apply to all the vineyards of the Sandusky dis- 
trict. On the contrary, these dates apply only to the crops sampled. 
The season for Catawba in the Sandusky district lasts fully 3 weeks 
and the ripening of other- varieties extends over a considerable 
period, varying with location. 
Clinton was sampled for 21 days after the crop was picked, but 
shows only an increase of 1.43 grams of sugar and a loss of 0.18 
gram of acid. This variety lost most of its foliage before the fruit 
was picked on October 7 and 8 and the later samples were picked 
from vines practically bare of leaves. This undoubtedly had an 
influence on the high acid shown. In fact, this crop of Clinton 
shows the maximum acid at ripening of all the crops of this variety 
examined at Sandusky during the season of 1911. The fact that 
this variety showed such high content of both nialic acid and cream 
of tartar at ripening should be noted in this connection, because the 
presence of those elements greatly assists in the reduction of the 
acid of the finished products from this variety. This occurs by 
precipitation of the crude tartar both in grape juices and wines and 
by destruction of nialic acid with the formation of lactic acid through, 
bacterial fermentation 2 in case of wines. 
The Delaware samples at Sandusky show the most notable increase 
of sugar after the date the crop was marked wine-ripe. However 
important it might appear to be to secure this increase of nearly 
3 grams of sugar in 100 cc of juice, it is not practicable to hold this 
crop so late because of the injury to the. fruit from birds, insects, 
and various other causes. The acid reduction was inappreciable, 
but as a matter of fact this variety has scarcely enough acid when 
it is fully ripe for the best results in dry-wine making. Note the 
unusually wide total acid-sugar ratio in Table 2. 
Ives, though held on the vine 14 days after marked fully ripe, 
showed very slight changes in sugar and acid. 
1 Kulisch, Weinverbessening, 3d ed. # 1909, p. 19. 2 Ibid. 
