6 OF THE FOOD OF PLANTS. Parti. 



To this it is anfwered; that there is no doubt but that the particles 

 which plants appropriate to themfelves, take different forms in each 

 plant : but it does not at all follow, that they were not the fame in 

 the earth. 



What would induce us to think them the fame, Is, that plants 

 rob one another, if we may fo fay, of the nourifhment that is in the 

 earth. For, if a lettice, for example, drew from the earth a food 

 different from that of endive, a lettice planted among endive would 

 not only thrive better than if planted among other lettice, but as 

 well as if no other plant was near it : but we know by experience 

 that this lettice would thrive very poorly, and confequently that 

 plants, tho' of different fpecies, do hurt and rob one another. 



To prove that the fame juice takes different qualities in the veffels 

 of the fame plants, M. Duhamel mentions an experiment which he 

 niade long ago. He grafted a young lemon, of the fize of a pea, 

 by the ftalk, upon the brancli of an orange-tree. It grew there, 

 ripened, and retained its quality of lemon, without partaking in 

 any fliape of that of the orange. The juices of the orange-tree 

 muft therefore have changed their nature at once, on their paffmg 

 into the lemon. 



2. As a fecond proof of this, he afks, why barley or oats is 

 fown after wheat, but becaufe the wheat has drained the earth 

 of thofe juices only which are proper for its own fpecies ; and the 

 juices proper for the nourlfliment of barley, or oats, ftill remain 

 in the earth? 



The anfwer is, i. If barley grows well after wheat, for no other 

 reafon than becaufe the earth has retained that kind of juice which 

 is proper for its nourifhment, it would follow that we might expert 

 a good crop from wheat fown upon barley ftubble, becaufe the 

 barley had not confumed the juices fit for the nourlfliment of wheat. 

 Yet we may be fure the crop would be very bad ; becaufe wheat 

 never thrives well, but upon land that is in fine tilth. If barley was 

 to be fowed in land in as good condition, we fhould be more 

 certain of an excellent crop. But as barley is lefs valuable than 

 wheat, and does not require fo loofe a mould, it is fowed after only 

 two plowings. 2. If each plant drew from the earth none but thole 

 juices which are proper to Its Ipecies, why need the land be fallowed 

 every third year ? We need only fow wheat the firll year, barley 

 the fecond, oats the third, peas the fourth, and turneps the fifth ; 



fo 



