154 ON THE FOOD OF PLANTS. 



the repeatedly stirring and turning it up, and 

 exposing it to the action of the sun, light, and 

 air ; paring and burning ; the addition of lime, 

 and the calcareous and saline substances ; and, 

 above all, the production, presence, and reten- 

 tion of carbonic acid ; all corroborate my prin- 

 ciples. 



And if all physiologists do not agree, that car- 

 bonic acid forms the productive food of plants ; 

 all accord in the doctrine, that those substances 

 which either contain, or are capable of pro- 

 ducing carbonic acid : are conducive to the fer- 

 tility of the soil, and congenial to the health and 

 fructification of plants. I therefore cannot but 

 think the following are the true inferences; that 

 in the decomposition of vegetables and animals, 

 or the preparation of the food of plants ; (so far 

 from hastening,) every means should be adopted 

 that anticipate, or precede, the putrefactive fer- 

 mentation, in the reduction of those substances 

 to a soluble state j — that vegetable substances 

 should be managed and disposed, so as to effect 

 and encourage the saccharine fermentation to the 

 utmost ; before they are exposed to the putrefac- 

 tive, which is done by effectually drying them in 

 the sun and air ; — and that animal substances 

 should, as much as possible, be placed under those 

 circumstances which favour the formation and 



