Sed. VI. Agriculture and Vegetation. 179 



iited. In this way particles of any fize 

 may be lodged in any part of the plant. 

 Hence all that variety in the falts, oils, 

 cmd figures of plants. Hence all that va- 

 riety of fmells, taftes, virtues, and other 

 qualities. 



How ftrong the power inherent in the 

 veffels of plants to change and alter thofe 

 fubflances which are taken in> appears 

 from an experiment of Homberg. He filled 

 two pots of earth mixed with fome falt- 

 petre. Into one he put creffes, which is 

 an alkalefcent plant, and affords a volatile 

 alkaline fait, but no acid ; into the other 

 fennel, which is an acefcent plant, and 

 affords an acid on diftillation, and no al- 

 kaline volatile fait. He filled two other 

 pots with earth, which had all its falts 

 warned out, if there were any in it. Into 

 one he planted fennel, and into the other 

 creffes, as in the former. The two plants 

 in the nitred pots grew much better, and 

 weighed much more than in the pots with- 

 N 2 out 



