270 MATURATION OF THE PERICARP. 



the bark. Succulent fruits contain a large quantity of water, along 

 with cellulose or lignine, sugar, gummy matter or dextrine, albumen, 

 colouring matter, various organic acids, as citric, malic, and tartaric, 

 combined with lime and alkaline substances, besides a pulpy gelatinous 

 matter, which is converted by acids into pectine or pectose, whence 

 pectic acid is formed by the action of albumen. Pectine is soluble 

 in water, and exists in the pulp of fruits, as Apples, Pears, Goose- 

 berries, Currants, Raspberries, Strawberries, &c. Pectic acid is said 

 to consist of C u H s O 12 + HO. It absorbs water, and is changed 

 into a jelly-like matter; hence its use in making preserves. Each kind 

 of fruit is flavoured with a peculiar aromatic substance. Starch is 

 rarely present in the pericarp of the fruit, although it occurs commonly 

 in the seed. In Plantains, Bananas, and Bread-fruit, however, 

 especially when seedless, there is a considerable quantity of starchy 

 matter, giving rise to mealiness when these fruits are prepared as 

 fritters. Oily matters are also found in the cellular tissue of many 

 fruits. Thus, a fixed oil occurs hi the Olive, and essential oils in the 

 Orange, Lemon, Lime, Rue, Dictamnus, &c. 



565. During ripening, much of the water disappears, while the 

 cellulose or lignine, and the dextrine, are converted into sugar. The 

 acids also combine with alkalies, and thus the acidity of the fruit 

 diminishes, while its sweetness increases. In the Grape, when young, 

 there is abundance of tartaric acid; but as the fruit advances to matu- 

 rity, this combines with potash, so as to diminish the acidity. Certain 

 fruits owe their aperient qualities to the saline matter which they 

 contain. In seasons when there is little sun, and a great abundance 

 of moisture, succulent fruits become watery, and lose their flavour. 

 The same thing frequently takes place in young trees with abundance 

 of sap, and in cases where a large supply of water has been given 

 artificially. 



566. The following analysis of the Cherry in its unripe and ripe state, 

 as given by Berard, exhibits generally the chemical composition of 

 succulent fruits : 



Unripe. Ripe. 



Chlorophylle 0-05 



Sugar 1-12 18-12 



Gum or dextrine 6'01 3'23 



Cellulose 2-44 1'12 



Albumen 0-21 0.57 



Malic acid 1-75 2'01 



Lime 0-14 0-10 



Water.... ....88-28 74-85 



100-00 100-00 



The following table shows the changes produced on the water, sugar, 

 and cellulose, in 100 parts of unripe and ripe fruits : 



