Chap. II. O/Food c/Plants. to 



nothing. So that this Inftance of Sedums, &c 

 which they pretend to bring for Proof of this their 

 Hypothefis, is alone a full Confutation of it. 



Yet if granted, that Air could nourifh fome Vege- 

 tables by the earthy Effluvia, &c. which it carry'd with 

 it (tfj, even that would be againft them, not for them. 



They might as well believe, that Martins and 

 Swallows are nourim'd by the Air, becaufe they live 

 on Flies and Gnats, which they catch therein •, thfia 

 being the fame Food, which is found in the Stomach 

 of the Chameleon. 



If, as they fay, the Earth is of little other Ufe to 

 Plants, but to keep them fix'd and fteady, there 

 would be little or no Difference in the Value of rich 

 and poor Land, dung'd or undung'd ; for one would 

 ferve to keep Plants fix'd and fteady, very near, if 

 not quite as well as the other. 



If Water or Air was the Food of Plants, I cannot 

 fee what Neceflity there mould be of Dung or Tillage. 



4. Fire. No Plant can live without Heat, tho' 

 different Degrees of it be neceffary to different Sorts 

 of Plants. Some are almoft able to keep Company 

 with the Salamander ', and do live in the notteft Ex- 

 pofures of the hot Countries. Others have their 

 Abode with Fifhes under Water, in cold Climates: 

 for the Sun has his Influence, tho' weaker, upon the 

 Earth cover'd with Water, at a confiderable Depth ; 

 which appears by the Effedr. the Viciffitudes of Winter 

 and Summer have upon fubterraqueous Vegetables. 



Tho' every Heat is faid to be a different Degree 

 of Fire ; yet we may diflinguifh the Degrees by their 

 different Effects. Heat warms ; but Fire burns : The 

 firft helps to cheriih, the latter deitroys Plants. 



(a) This is meant of dry Earth, by its Lightnefs (when pul- 

 veriz'd extremely fine) carried in the Air without Vapour : For 

 the Atmofphere, confifting of all the Elements, has Earth in it in 

 confiderable Quantity, mix'd with Water ; but a very little Earth 

 is Co minutely divided, as to fly therein pure irom Water, which 

 is its Vehicle there for the mofl: Part. 



C 2 5. Earth, 



