EXTRACT S — F OREIGN AND DOMESTIC. 329 



seeds of oleaginous plants, albumen^ and a substance greatly resem- 

 bling casein. 



The vegetable fibrin of the seeds of cereals is accompanied by 

 starch. This same body is a principle of the pods of leguminous 

 plants. In the oleaginous seeds the starch is replaced by another 

 nitrogenous principle, analogous to oil, butter, or wax. 



It is evident that, according to the object of culture, and accord- 

 ing to the principles which we wish to obtain, we should present 

 to plants the conditions necessary for their production. Sugar 

 and starch require the addition of other substances than the sul- 

 phuro-nitrogenous principles. 



To furnish to the potatoe and the beet-root the necessary princi- 

 ples of their leaves, that is to say, organs destined for the absorp- 

 tion and assimilation of carbonic acid, is to fulfil the conditions of 

 the formation of starch and sugar. 



The juice of all vegetables rich in sugar and starch, and most 

 Df the ligneous plants, is rich in potassa, soda, or the alkaline 

 ;arths. These alkalies and alkaline earths cannot be considered as 

 iccidental principles ; we must suppose that they answer certain 

 )bjects in the organism of the plant, and that they are absolutely 

 lecessary for the formation of certain combinations. I have said 

 iiat they are combined in plants with organic acids which charac- 

 erize some kinds of vegetables, so that they are never wanting. 

 The organic acids themselves should be the intermedia of certain 

 dtal functions in the organism of the plant. Now, if it be borne 

 n mind, that fruits, before arriving at maturity, grapes for exam- 

 )le, are not eatable on account of their great quantity of acid, that 

 hese fruits act absolutely like leaves in the solar light, endowed, as 

 hey are, with the power of absorbing carbonic acid, and of elimi- 

 lating oxygen (De Saussure); that the augmentation of the sugar 

 ;oincides with the diminution of the acid, we can scarcely help 

 hinking that the carbon of the organic acid in the fruit, before its 

 Qaturity, becomes a principle of sugar in the ripe fruit, that it is 

 bus, by an elimination of oxygen, with an assimilation of the ele- 

 Qents of water, that the acid is converted into sugar. 

 The tartaric acid in grapes, the citric acid in cherries and goose- 

 erries, and the malic acid in summer apples which ripen on the 

 fees, are, therefore, the intermedia of the conversion of carbonic 

 cid into sugar ; deprived of the proper temperature, and of the 

 ction of the solar light, they would not undergo the changes of 

 bis metamorphosis. 



Now, we see in the sorb apple of bird-catchers {sorhier des oise- 

 eurs^) the tartaric acid replaced by malic acid, the more oxyge- 

 ous acid by the acid containing less oxygen ; we see the malic 

 cid gradually, almost completely disappear from these fruits, and 

 'e find in its place gum and mucilage, which did not previously 

 sist in them, and, consequently, we have reason to admit the con- 



VOL. I. NO. II. K 



