74 FOOD OF THE VEGETATING PLANT. CHAP. II. 



of all vegetables ;* and who will say that it is not 

 essential to their perfection ? 



SECTION V. 

 Earths. 



As most plants have been found by analysis to 

 contain a portion of alkaline or earthy salts, so most 

 plants have been found to contain also a portion of 

 earths : and as the two substances are so nearly 

 related, and so foreign in their character to vege- 

 table substances in general, the same inquiry has 

 consequently been made with regard to their origin. 

 Whence are the earths derived that have been found 

 to exist in plants ? 



Whether It seems to have been the opinion of Lampadius 

 the'pro- 111 th^ the earths contained in plants are merely the 

 T S 'etaUon e ^ ect ^ vegetation, and altogether independant of 

 the soil in which they grow : and extravagant as 

 the opinion is, it has been made to assume the sem- 

 blance of resting upon experiment. Lampadius 

 prepared, in his garden, five small beds of four feet 

 square in surface by one in depth ; each bed con- 

 sisted of a pure earth mixed with eight pounds of 

 cow-dung. The earths were alumine, silica, lime, 

 magnesia, and garden mould. They were sown 

 with Rye, and the produce of each was separately 

 * Saus. sur la Veg. chap, viii. sect. iv. 



