126 GERMINATION. 



moisture while in the fleshy comparatively little evaporation 

 took place from the small number of stomates on its surface. 

 The effects of fruits, uhen green, on the atmosphere, are the 

 same as those of the leaves, but generally of a more limited 

 extent. In the night they absorb oxygen like the leaves, and 

 return most of it during the day. 



This continues during their green state, and but little 

 change occurs in the ripe stage, only more oxygen is returned 

 to the atmosphere, thus making it probable that the acidity 

 and harshness of green fruit is owing to the oxygen it contains 

 in its composition. 



158. The constitution of the fruit differs materially in its ripe, 

 from what it was in the green state. Water and lignine di- 

 minish, and sujiar increases. Water diminishes from two to 

 ten per cent in different kinds. Lignine generally in a greater 

 proportion. Sugar increases in currants from 52 to 6.25, 

 it being twelve times the quantity in a ripe from what they 

 possessed in a green state. This, the remarkable changes in 

 taste would lead us to suppose without analysis. The man- 

 ner in which this change takes place, is as yet undetermined. 

 In many cases we know that sugar is produced at the expense 

 of starch, but no starch can be discovered in those fruits 

 which generate the greatest amount of sugar, such as Cur- 

 rants, Apples, Peaches, &;c. Tiiat it takes place at the ex- 

 pense of ttie other proximate principles aided by water, is cer- 

 tain, since it goes on without any increase of weight, and 

 even when separated from the parent stock, and also in the 

 process of cooking. It is a well known fact in chemistry, 

 that the action of various vegetable substances on each other, 

 aided by moderate heat, will produce the saccharine principle. 

 The vegetable acids with gum and mucilnge will produce this 

 efTect, and so will sulphuric acid by its action on lignine or 

 starch. These principles are contained in all succulent fruits, 

 tartaric acid, malic acid, gum and various other substances 

 peculiar to each fruit. The act of ripening, therefore, is a 

 chemical process, which consists in converting the various 

 unpleasant and injurious principles of the green fruit, into 

 X)ne of the most nourishing and healthy of vegetable products. 

 159, Although the above conveys the general principles 

 on which, we believe, the ripening of fruit proceeds, yet in 

 some cases, in^sQ substances, from which we suppose the su- 

 gar to be formed, increase at the same time; yet we believe 

 that in all cases, either the acid or the other principles dimin- 

 ish, and never both increase or remain stationary in the same 



