FRUITING. 113 



small number of stomata on its surface. Tne effects of fruits, 

 when 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. 



201. The constitution of the fruit differs materially in its 

 ripe from what it was in the green state. Water and ligtiine 

 diminish, and sugar increases. Water diminishes from two to 

 ten per cent, in different kinds ; lignine generally in a greater 

 proportion. .Sugar increases in currants from 0.52 to 6.25, it 

 being twelve times the quanti-ty in a ripe from what they pos- 

 sessed in a green state. This the remarkable changes in taste 

 would lead us to suppose without analysis. 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 Currants, Apples, Peaches, 

 &c. That it takes place at the expense of the other proximate 

 principles, aided by water, is certain, 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 

 mucilage, will produce this effect. These principles are con- 

 tained in all succulent fruits, tartaric acid, malic acid, gum, and 

 vai'ious other substances peculiar to each fruit. The act of 

 ripening, therefore, is a chemical process, which consists in con- 

 verting the various unpleasant and injurious principles of the 

 green fruit into the most nourishing and healthy of vegetable 

 products.!^ 



202. Although the above conveys the general principles on 

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

 cases these substances from which we suppose the sugar to be 

 formed increase at the same time ; yet we believe that in all 

 cases either the acid or the other principles diminish, and never 

 both increa&e or remain stationary in the same fruit. If the 

 acid increases, the other principles diminish. If the other 

 principles increase, the acid diminishes. 



For these processes to go on, an jitmosphere containing oxy- 

 gen is necessary ; showing that this active agent is required in 

 these operations, and performs some necessary office in the con- 



201. How does the constitution of ripe frnit differ from unripe ? What 

 is well known in chemistry? Is the act of ripening a cliemioal process? 

 —202. What seeming variatiou from the above ? What necessary for these 

 processes to be good ? 



