128 BIOLOGY OF PLANTS. 



have been found in the vegetable kingdom, and which cannot, 

 with but few exceptions, be formed h}^ any known chemical 

 agents. This enumeration will perhaps lead some scientific 

 farmers to examine more fully the vegetable principles, and to 

 study in works where they are found fully described, their cha- 

 racters and uses. 



It jnay, however, be useful, and much more intelligible to the 

 common reader, to describe the sources of several articles of 

 food and of medicine, as they exist in the roots, wood, bulbs, 

 leaves, fruit, or seeds of plants. 



I. Roots. The principal roots, employed in medicine and 

 the arts, are the following. 



1. Beet-root {beta vulgai'is). There are two varieties, the red 

 and the white beet. This is a well known vegetable. It con- 

 tains from 5 to 10 per cent, of sugar, generally from 8 to 9 per 

 cent. ; hence its use for this purpose. 



2. Cairot [dauciis carota). This is also a well known root. It 

 is used for fattening cattle, and is preferable to the beet for that 

 purpose. It contains sugar, and a peculiar principle, called 

 caratin. 



3. Rhuharh [rheum plamatum, ausfrale, undulatum, etc.) Three 

 varieties of rhubarb are known in commerce, Russian, Turkey, 

 East India or Chinese rhubarb. It is a yellow root possessing 

 powerful purgative properties, for which it is used in medicine. 



4. Rattle-snake root {polygala senega), is a native of Virginia, 

 and is employed by the Indians as a cure for the bite of the 

 rattle-snake. The peculiar vegetable principle upon which this 

 effect depends, is called senegin. 



5. Jalap [Jpomea jalappa), is a well known active cathartic. It 

 is a native of Mexico, but the best jalap comes from Vera Cruz 

 and South America. The active properties are supposed to be 

 due to the resin which it contains. 



6. Gentian [gentiana lutea), grows in the mountains of Swit- 

 zerland and America, and is a bitter root, yielding to water an 

 extract, which produces intoxicating effects. 



7. Valerian {Valeriana ojficinalis), is a root much used as an 

 anti-spasmodic in epilepsy, etc. 



8. Horse-radish {cochlearea aimorica), is a root of an acrid 

 taste, which is due to a small quantity of volatile oil. 



9. Siveet-Jlag {acorus calamus), contains a volatile oil, inuline, 

 gum-extractive, resin, with phosphate and muriate of potash. 



