198 THE NATURAL HISTORY 



The productions of vegetation have had a vast influence 

 on the commerce of nations, and have been the great 

 promoters of navigation, as may be seen in the articles 

 of sugar, tea, tobacco, opium, ginseng, betel, paper, etc. 

 As every climate has its peculiar produce, our natural 

 wants bring on a mutual intercourse ; so that by means of 

 trade each distant part is supplied with the growth of every 

 latitude. But, without the knowledge of plants and their 

 culture, we must have been content with our hips and 

 haws, without enjoying the delicate fruits of India and the 

 salutiferous drugs of Peru. 



Instead of examining the minute distinctions of every 

 various species of each obscure genus, the botanist should 

 endeavour to make himself acquainted with those that are 

 useful. You shall see a man readily ascertain every herb 

 of the field, yet hardly know wheat from barley, or at 

 least one sort of wheat or barley from another. 



But of all sorts of vegetation the grasses seem to be 

 most neglected ; neither the farmer nor the grazier seem to 

 distinguish the annual from the perennial, the hardy from 

 the tender, nor the succulent and nutritive from the dry 

 and juiceless. 



The study of grasses would be of great consequence 

 to a northerly, and grazing kingdom. The botanist that 

 could- improve the sward of the district where he lived 

 would be an useful member of society : to raise a thick 

 turf on a naked soil would be worth volumes of systematic 

 knowledge; and he would be the best commonwealth's 

 man that could occasion the growth of " two blades of 

 grass where one alone was seen before." 



I am, etc. 



