294 PHYSIOLOGY. BOOK II. 



" Tliese results are often not observable in volumes of air 

 less than from 30 to 40 times that of the volume of the fruit, 

 and by diminishing the heating power of the sun. If such 

 precautions are neglected, many fruits will vitiate the air even 

 in the sun by forming carbonic acid with the ambient oxygen; 

 but, even in the latter case, the simple comparison of their 

 effect in light, with what they produce under the influence of 

 night and darkness, demonstrates that they decompose car- 

 bonic acid." 



In ripening, fruits undergo some remarkable alterations, 

 which have been extremely well explained by De Candolle 

 in his condensations of Berard's observations : — 



" If we examine the modifications which the flesh of fruits 

 undergoes in ripening, we shall at first remark that their 

 fibrous or cellular tissue (which varies very much in quantity 

 in different species)' is merely lignine : in most cases, espe- 

 cially in very fleshy fruits, lighter, less tough, and more easily 

 soluble in alkaline solutions than common lignine ; but pre- 

 senting characters of an opposite kind in other parts of the 

 same fruit, such as their stones. 



" The liquid which fills the flesh of succulent pericarps con- 

 sists of sap placed in the intercellular passages and of the 

 matter contained in the cells. This liquid of the flesh, or of 

 the fleshy endocarp, contains, besides a great quantity of 

 water, sugar, gum, malic acid, malate of lime, colouring 

 matter, a peculiar vegeto-animal substance, and an aromatic 

 secretion proper to each fruit : there is, moreover, in certain 

 cases, the tartrates both of potash and of lime, as in Grapes ; 

 and citric acid in the Lemon, and even in small quantity 

 in the Gooseberry." Berard could find no trace of starch in 

 watery fruits, such as Cherries, Plums, Peaches, Currants, 

 Grapes, nor even in Pears and Apples, although it has been 

 said to exist in them. 



" A comparison of the analysis of certain fruits, before they 

 are ripe and at that period, gives some curious results. In 

 the first place there is a disappearance of water in a liquid 

 state, viz., per cent, — 



