12 STUDIES ON APPLES. 



(glucose) formed from starch by the action of acids was found by Biot 

 to be not the same as the sugar in fruits. 



Some of the ideas of Fremy were vigorously combated by Cou- 

 verchel." 



A veiy valuable contribution to the subject of the analysis of fruits 

 by Buignet, b which appeared in 1860, is of interest because of the 

 methods given for the determination of many constituents of the -straw- 

 berry. Water, acid, sugars, fat, soluble and insoluble protein, marc, 

 nitrogen-free parenchyma, pectin, odoriferous principles, coloring 

 matters, and ash are worked out. Strawberries containing the least 

 water are said to contain the most sucrose, and this is explained on 

 the h} 7 pothesis that the acid and sucrose are contained in different cells, 

 and in the presence of much water these diffuse more readily than in 

 drier berries, a more rapid inversion ensuing. Sucrose is believed to 

 be the initial sugar formed. Results for many varieties of strawber- 

 ries are tabulated. A later paper c gives results concerning sugars 

 in fruit in the form of a summary of 14 conclusions, some of which 

 are as follows: Sucrose is found in many fruits, becoming inverted in 

 the ripening, sometimes complete!} 7 , e. g., in grapes, currants, and 

 figs; sometimes partially, e. g., in bananas, apricots, peaches, plums, 

 apples, and pears. No relation exists between .sucrose and the acidity 

 of fruits, but the sugar is probably inverted b} T a nitrogenous ferment. 

 This was proved by showing that, after precipitating with alcohol, the 

 sucrose remained unchanged; that after neutralizing an original sample 

 of juice with calcium carbonate, the 'inversion still went on; and that 

 in bananas, which have no free acid, starch is -rapidty changed to 

 sucrose. Invert sugar prevents the crystallization of sucrose, but the 

 latter sugar was isolated in crystals from a number of fruits by a pro- 

 cedure which is described. Starch was not found in fruits (except the 

 banana), but a tannin-like, astringent principle is described as occur- 

 ring in unripe fruits, which decolors an iodin solution, yielding a pre- 

 cipitate which, when treated with acid, yields a glucose sugar, the same 

 as that formed from nut galls. The starch and tannin found in the 

 banana are said to disappear simultaneously, giving rise to cane sugar. 

 Finally we are told that a difference exists between sugars of fruits 

 according as they are produced under action of vegetable forces, or 

 without it, e. g. , bananas contain more sucrose and less invert sugar 

 when allowed to ripen on the tree than if ripened after picking. 



Berthelot and Buignet d worked on the ripening of oranges. Two 

 samples of green oranges were studied. Several fruits from each 



Compt. rend., 1844, 19: 1114. 



&J. pharm. chim., 1859 (3), 36: 81-111 and 170-198; resume in Compt. rend., 

 1859, 49 : 276-278. 



c Compt. rend., 1860, 51: 894. 

 d Ibid.: 1094. 



