MATURATION OF THE PEKICAEP. 321 



Dry fruits may remain attached to the tree for some time before 

 they are fully ripe, and ultimately separate by disarticulation. 

 Occasionally, ■when the pericarp is thick, it separates in layers like the 

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

 cellulose, 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, 

 containing pectose, the characteristic constituent of unripe fruits. 

 This substance is quite insoluble in water, but during the ripening of 

 the fruit it is converted by the vegetable acids into pectine, which is 

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

 Gooseberries, Currants, Raspberries, Strawberries, etc. This substance 

 undergoes a further change, being converted into pectic acid 

 (Q16 JJ22 Qis) and pectosic acid (0=^ H« O'^). These are easily soluble 

 in boiling water and gelatinise on cooling (•s-jjzro's, congealed) ; hence 

 their 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. 

 Oily matters are also found in the cellular tissue of many fruits. Thus, 

 a fixed oil occurs in the Olive, and essential oils in the Orange, Lemon, 

 Lime, Eue, Dictamnus, etc. 



During ripening much of the water disappears, while the cellulose, 

 lignine, and the dextrine, are converted into sugar. Berard is of 

 opinion that the changes in fruits are caused by the action of the 

 oxygen of the air. Fremy found that fruits covered with varnish did 

 not ripen. As the process of ripening becomes jierfected the acids com- 

 bine with alkalies, and thus the acidity of the fruit diminishes, whUe 

 its sweetness iacreases. The formation of sugar is by some attributed 

 to the action of organic acids on the vegetable constituents, gum, dex- 

 trine, and starch ; others think that the cellulose and lignine are 

 similarly changed by the action of acids. The sugar of fruits is grape 

 or starch sugar, called also Glucose. Its formula is C H" 0'. In the 

 Grape, when young, there is abundance of tartaric acid ; but as the 

 fruit advances to maturity 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. 



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

 as given by Berard, exhibits generally the chemical composition of suc- 

 culent fruits : — 



