LECT. V.] THE ROOT. SOILS. 237 



manures, and the food of plants, which the con- 

 sideration of the structure and the use of roots to 

 the plant have suggested. It may be thought that 

 I have travelled out of the proper path, in giving 

 even the slight view of them which I have at- 

 tempted; but my object is to excite those who 

 have leisure and opportunity to examine more 

 closely a subject so intimately connected with 

 the prosperity and happiness of our country, and 

 the most essential interests of the human race. 



We have noticed the importance of the root 

 as a vegetable organ, but it is not less interesting 

 as yielding medicinal agents, supplying dying 

 materials, and affording an abundant store of food 

 for man and other animals. Many of the secreted 

 juices of plants which are deposited in the roots, 

 particularly when the stems annually decay, pos- 

 sess medicinal properties. Indeed, there is scarcely 

 one of the divisions of the Materia Medica in 

 which some of the roots, or their appendages, are 

 not to be found. Thus, among the EMOLLIENTS we 

 find the roots of Marsh Mallow, Althaea officinalis, 

 of Sarsaparilla, Smilax sarsaparilla, and of Liquo- 

 rice, Glycyrrhiza glabra, yielding demulcent and 

 saccharine mucilages. Among STIMULANTS, which 

 produce their specific action on particular or- 

 gans, the bulbs of the white Lily, Lilium can- 

 didum, and of Garlick, Allium sativum, may be 

 employed to affect the skin as rubefacients and 



