167 



I know of no special investigations of the case at hand. On this account it 

 can be stated only hypothetically that the mealiness of the fruit depends upon 

 a definite act in the ripening process, which has been directed into other chan- 

 nels because of the scarcity of water. This change in direction might not be as- 

 sociated with the connection of the fruit and the tree, but may set in late in 

 the development of the fruit, about at the time when the intercellular sub- 

 stances generally dissolve. In normal ripening of fruit, after passing the 

 stage of great sweetness, in which the fruit is already "mellowing," i. e., the 

 cells of its flesh are easily separated from one another, there occur at the 

 expense of the sugar first an alcoholic and finally an acetic acid fermen- 

 tation. The fruit becomes winey and doughy with a constantly advancing 

 oxidation or browning. According to Fremy^, a part of the alcohol thus 

 formed is combined with the fruit acids to form the ethers, which condition 

 the flavor of the fruit. A cool temperature prevents the rapid oxidation of 

 the sugar. The supply of water from the branch to the fruit, becoming less 

 with ripening, explains the fact that, in great summer heat, the fruit develops 

 with extraordinary rapidity and in this gives off carbon dioxid and water 

 abundantly. In fruit, however, the flesh is poorer in water and is very 

 easily warmed through ; the reduction of the intercellular substances, which 

 we reckon among the pectines, cannot take place in the usual way. A. 

 Mayer- considers the pectines as condensation-products of Galactose and 

 the pentoses, Arahanose, and calls attention to the peculiar fact that they 

 are jelly-hke because of a special enzyme and are hydrolized by another to 

 the pentoses. It may indeed be assumed that these processes are changed 

 quantitatively and qualitatively when the fruit becomes mealy. This is indi- 

 cated by the circumstance that in mealy fruit a firm connection always exists 

 between the outer skin and the flesh of the fruit, while in the normal winey- 

 doughy condition the outer skin can be raised easily from the flesh, i. e., the 

 intercellular substance is dissolved. The insipid taste of mealy fruit is ex- 

 plained by the scanty content of acid and the quick destruction of the sugar. 



When establishing the theory that an excess of warmth can cause a 

 relative lack of organic acids in fruit, attention must be called again to the 

 fact that the acids formed in the leaves during the night are in great part 

 used up again during the following day. This process of oxidation will also 

 take place in green fruit and it is indeed conceivable that in the long, hot 

 summer days, this is so intensive that a large part of the acids already pro- 

 duced disappears. Under such circumstances no vinous fermentation takes 

 place. 



The fact that I was able artificially to produce the mealy process in 

 apples favors the theory that the mealiness of fruit appears with the scarcity 

 of water in the cells and a pasty decomposition of the cellular substance, if 

 the conditions necessary for a vinous fermentation are not present. Fruit 

 of various sorts was packed in layers in dry sand after ripening normally 



1 Compt. rend. LVIII, p. 656. 



~ Agrikulturchemie, 5th. Ed. Vol. I, p. 141. Heidelberg 1901. 



