PART IV. AGRICULTURE. 189 



all who would acquire a knowledge of this kingdom of nature. 

 The use of this system of natural history is extensive ; it assists 

 the memory in recollecting the qualities of vegetables, both of 

 individuals and of general classes ; it enables us to derive 

 advantages from the writings and discoveries of authors ; and, by 

 ascertaining to what link of the system a new or unknown plant 

 belongs, to communicate intelligibly our ideas to others. 



3. The Properties of Vegetables— By this is meant their place 

 of growth, their natural soil, exposure, climate, longevity, time 

 of flowering, &c. It is discovered by observation, and ought 

 to be recorded in all complete descriptions of vegetables. It 

 is of great utility to agriculturists, by enabling them to adopt 

 proper modes of cultivating useful plants, or destroying pernici- 

 ous ones, and also to discover the soils and plants reciprocally 

 adapted to each other. "With respect to proper modes of cul- 

 ture, it directs the choice of suitable agents, as soil, situation, 

 climate, moisture, &c. It also shews the proper season of sow- 

 ing or planting, reaping and renewing the crop. With regard 

 to destroying pernicious vegetables or weeds, it teaches us, that 

 many plants die when cut down immediately before they come 

 into flower ; that others are prevented from producing seed, 

 and thus rendered less pernicious by this practice ; that some 

 produce and scatter their seeds in a few days after they have 

 ceased flowering, as the hieracium vulgaris and tussilago forfara, 



