THE FOURTH EDITION. 9 



which differ from each other in value, two only have 

 been cultivated separately, to any extent. This may 

 appear extraordinary; but there have been difficulties 

 in the way. 



Grass, says Professor Martyn, vulgarly forms one 

 idea ; and a husbandman, when he is looking over 

 his enclosure, does not know that there are three hun- 

 dred species of grass, of which thirty or forty may be 

 at the moment under his eye. They have scarcely 

 had a name, besides the general one, until within 

 these twenty years ; and the few particular names 

 which have been given, are far from having obtained 

 general use ; so that we may fairly assert, that the 

 knowledge of this most common and useful tribe of 

 plants is yet in its infancy. Of the one hundred and 

 thirty-three distinct species and varieties of grass, 

 natives of the British Isles, many are of no value to 

 the farmer, w^iile others constitute the foundation of 

 his riches, as they are the staff of life to the most 

 valuable domestic animals. Now^ though they are 

 very different in value, they are mostly similar in 

 appearance ; and therefore recourse must be had to 

 the botanical distinctions which are the least subject 

 to change. But these being often minute, the inves- 

 tigation of them is often perplexing even to botanists; 

 and consequently, to those who know nothing of that 

 science, their specific distinctions must always be a 

 matter of difficulty. But allowing that the different 

 grasses were easily distinguished, and that farmers 

 w^ere in possession of the seeds, the length of time 

 which would be required to prove their relative value, 

 by the usual way of experimenting on a farm, would 



