NOURISHMENT OF PLANTS. 



25 



from a volatile oil. In the seed of our various kinds 

 of grain, and in the tubers of the potato-plant, we 

 find a substance resembling meal, starch; in the 

 seed of the rape and flax plants, a lubricous fluid, 

 fat oil. From the cherry and plum trees there ex- 

 udes a viscous matter, soluble in water; from fir 

 and pine trees a similar product, but insoluble in 

 water ; we call the former gum, the latter resin. 

 That which gives mechanical support to plants, 

 forming as it were their bones and blood-vessels, 

 receives the name of vegetable fibre, or, when it has 

 become tough, insoluble, or indigestible, the name of 

 woody fibre. In the sap of plants we meet with a 

 substance, which coagulates by boiling, like the 

 white of an e,^g or the albumen of the blood; in 

 pease and other leguminous fruits, a substance which 

 is extremely like cheese ; in the seed of rye, wheat, 

 oats, and other kinds of grain, a substance whose 

 composition is identical with that of the flesh of ani- 

 mals ; the first is called vegetable albumen, the sec- 

 ond vegetable caseine, and the third gluten. Finally, 

 on the combustion of the plant, we find a residue 

 consisting of an earthy or saline powder, which nei- 

 ther burns up nor volatilizes by heat ; this contains 

 its mineral constituents. 



By separating the various proximate constituents 

 of vegetables still further, we come to their more re- 

 mote elements and elementary substances, their ulti- 

 mate constituents. If man is seized with amazement 

 and admiration, when with intelligence and sensibil- 

 3 



