58 LETTER IV. 



possibility of intermixing- the races of plants, laid 

 the foundation of modern improvements in the qua- 

 lities of cultivated species ; while the ingenious but 

 derided speculations of Camerarius upon the relation 

 that exists between the properties and structure of 

 species, have put the physician in possession of a 

 power of discovering the hidden uses of plants, the 

 limits to the application of which no one can 

 foresee. 



It is mentioned, that in the voyage of Lord Anson 

 round the world, when new and unkno\Mi lands were 

 constantly discovered, the dread which his surgeon 

 entertained of the effect of strange herbs was so great 

 that, from fear of poisoning the crew, he would some- 

 times permit them to use no other kind of fresh ve- 

 getable food than grass. At the present day there 

 should be no nav\' surgeon who would not be able to 

 point out at once, in every place, an abundance of 

 plants, the use of which could not by possibility be at- 

 tended by any ill effects. You have already seen that 

 the Crowfoot tribe consists of burning and blistering 

 species, that the Poppy tribe produces stupefaction, 

 the Umbelliferous tribe is chiefly aromatic, but not 

 always to be trusted. Geraniums astringent, Evening 

 Primroses insipid, and Myrtles fragrant and aromatic. 

 Another example of the uniform prevalence of pe- 

 culiar properties in the same tribe or natural order, 

 is afforded by Cruciferous plants. 



The healthy stimulating effects of Mustard and 

 Cress, and the nutritive properties of Turnips and 

 Cabbages are well known to every body. These 



