14 STUDIES ON APPLES. 



Dupre, a however, noted a positive increase in acid in grapes during 

 ripening, disproving the conclusion of Petit. 



Neubauer 6 studied the ripening of grapes. The complete analysis 

 of two varieties of grapes at successive stages of growth is presented. 

 No satisfactory explanation could be given for the great increase of 

 sugar that took place on ripening. 



Famintzin" published the results of a study of the ripening of grapes, 

 which is of much interest because it explains the hitherto unknown 

 source of the sugars which appear in the grape on ripening. He used 

 both chemical and microscopical methods. Twelve analyses of a 

 variety of growing grapes are given and the results discussed. The 

 unripe grape contains no starch, but the stems of the fruit are full of 

 starch, which disappears as the grape ripens. Tannin was present 

 throughout the very young fruit, but later occurs only in the outer 

 layer of the fruit pulp and in the embryo. 



This work was confirmed by Hilger,^ who followed the changes of 

 water, ash, sugar, and acid content in the leaves and fruit of the grape 

 during growth. The stems of the fruit were found to be full of starch, 

 which disappeared when the rapid increase of sugar began. The 

 increase of sugar for a period of six days at the ripening time was 

 from 3.87 to 7.70 per cent in the case of one variety, and from 5.33 

 to 7.71 per cent in another, during which time the starch in the stems 

 disappeared. 



Mercadante 6 believed that the sugars were formed at the expense of 

 the gummy matters in the fruit, and also from acids, the fruit being 

 thus considered to be the seat of the formation of sugar. Macagnc/ 

 showed that sugar formation takes place in the leaves, not in the fruit 

 of the grape. 



Saintpierre and Magnien^ held a similar view. These authors first 

 give a review of the literature on fruit ripening. They found that 

 ripening fruits give off carbon dioxid in light or darkness, that they 

 absorb or give off water according as they are kept in a rnoist or dry 

 place, and that acid and sugar come to the fruit through the stem. 

 The acid is believed to be used up in respiration, the sugar meanwhile 

 concentrating in the fruit until in its turn it furnishes the carbon dioxid 

 for combustion. 



Pollacci, A studying the after ripening of grapes, found that the sugar 

 increased and the acid decreased in grapes stored after picking. 



Weinlaube, 18*70, p. 274, through A. Fitz, Ann. Oenol.-2: 241. 

 &Landw. Versuchs-Stat. , 1869, 11:416. 

 'Ann. Oenol., 1871, 2:242. 

 ^Landw. Versuchs-Stat., 1874, 17: 245. 



^Gazzetta chimica Italiana, 1875, 5th ser., p. 125, through Gerber, loc. cit. 

 /Compt. rend., 1877, 85: 763, 810, through Gerber, loc. cit. 

 <7Ann. agron., 1878, 4: 161. 

 1877, 3: 629. 



