Sect I. Agriculture and Vegetation. 119 



ment very rich, and in the former taken 

 from the fame place that the earth of the 

 foregoing was. 



Cor. 2. Plants feem to ftand in need of 

 a conftant application of free air to their 

 furfaces. All trees in thickets ftretch out 

 their branches either laterally or longitu- 

 dinally, where they can have moft air. Does 

 this air act only on their furface ? or does it 

 enter the vefTels of the plant ? If the latter, 

 is not an impetus from the air in motion ne- 

 ceffary in order to its entrance, as the mere 

 preflure of the air is always the fame in 

 fimilar altitudes ? 



Cor. 3 . The plants feem neither to have 

 been much better, nor much worfe, for the 

 addition of the faline mixture. 



Exp. 35. May 25, 1758, I fovved fome 



barley in 4 different pots, filled with the 



fame poor earth. N i, contains the pure 



earth. N 2. the fame earth frequently 



I 4 watered 



