24 DISQUISITIONS

S$ S§$

With regard to mankind, we know that many plants, which, when green, are hardly fit for food, become extremely nourifhing when dry;—and that fome are even poifonous in that ftate, which afterwards become an agreeable and wholefome food;—as the Caflava-root. And as thé wrus* of many plants de- pends upon a very volatile effential oil, that may be evaporated in drying the plants, as happens with regard to the root of the horfe-radith+, it is extremely probable that the qualities of the fame plant may frequently be very different in a dried ar a green ftate. Tull the farmer, therefore, is made acquainted with this particular, his knowledge is not fo great as it ought to be; and he muft be often at a lofs to know which plant he ought to cultivate

* T have- ventured to adopt this word, as I know no proper Englifh word that is equivalent to it-—lIt is here employed to denote that particular power by which

plants are enabled to produce any fenfible effect upon

the animal fyftem, whether this be falutary or perni- cious.

+ Cochlearia Amorica.