RKVlJiW. 



gum, and various other 6ulj8t:inc€>9 peculiar to each fruit. The act of riponinf;, tliero- 

 foro, is a clitmiical process, which consists in convcrtin;^ tlie various unpleasant and 

 injurious principles of the green fruit into the most nourishin;; and licaltliy of vegetable 

 products. 



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 wc believe that in all cases either the acid 

 or the other principles diminish, and never both increase 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 atmosphere containing oxygen is necessary ; showing 

 that this active agent is required in these operations, and performs some necessary oflSce 

 in the conversion of the crude materials of green fruit into the palatable one of the ripe." 



The chapter on " Germination " will reward an attentive perusal. We are em- 

 barrassed in selecting extracts, so uniformly interesting is the portion of the work 

 which treats of Physiological Botany, but must be indulged with the following : 



"The principal food of plants is water and carbonic acid and ammonia, which arc 

 received through the roots in a liquid state, and through the leaves in a gaseous form. 

 Besides these various salts enter in a greater or less dcsrec into the composition of 

 vegetables. 



To determine the food of plants, it is an important element in the investigation to know 

 of what the plant is composed. This has been determined by various philosophers with 

 great accuracy. The following is the constitution of some of the most common plants, 

 taking 1000 parts of the dry vegetable : 



Carbon 



Wheat 455 



Oats 507 



Peas 465 



Turnips 429 



Potatoes 441 



Ouie a uniformity will be observed in these elements ; about one half being carbon, less 

 than half oxygen ; about one-twentieth hydrogen, less than one-twentieth nitrogen, wiih a 

 much greater variation in the ashes, which consist mostly oi potash, silcx, lime, utilphur, 

 prospliorus, and some other elements in minute quantities. 



The first four elements are called organic elements, or organogcns ; the materials of the 

 ashes, inorganic elements. The most abundant element is carbon, and no organic product 

 exists without it, although either of the others may be absent. 



The plant derives its carbon from carbonic acid, C02. It cannot take up carbon 

 in an uncombined state, as it is solid, and it can obtain it from no other compound 

 of carbon, as no other exists in sufficient quantities. The carbonic acid in the air, the 

 result of respiration of animals, the combustion of wood and coal, and the decay of 

 carbonaceous substances, and that contained in the soil from the action of manure, 

 affords the plant its carbon. It is chiefly derived from the air. Numerous facts prove 

 this position. Originally, before there was any vegetation, there could have been 

 carbonic acid nowhere else. Plants grow in the air and deposit carbon. The growth of 

 plants increases the carbonaceous matter in the soil where they grow. Plants will grow 

 and increase in carbon in distilled water. These well-known facts prove that carbonic 

 acid in the atmosphere supplies most of the carbon to plants." 



