ORGANIC BODIES IN PLANTS. 41 



down; in the bark they run vertically, that is, toward 

 the centre of the tree. It is supposed that air obtains; 

 access to the body of the plant through these tubes. 



Leaves are usually considered an extension of the 

 bark. They have a net work of veins running through 

 them in every direction, conveying fluids to all parts; 

 an I also have on their outer surfaces, innumerable 

 little pores or mouths, through some of which they 

 hronthe out, and through others draw in, water and 

 various gases These functions of the leaf will be 

 noticed again in a subsequent chapter 



SECTION II. THE GREAT NUMBER AND DIVERSITY OF ORGANIC 

 BODIES IN PLANTS. 



The organic portion in these several parts of the 

 plant, consist of a great variety of substances, with 

 the more common of which at least, the farmer ought 

 to be acquainted. 



The organic bodies of plants are exceedingly 

 numerous. Almost every plant has some one or more 

 peculiar to itself. Thus we see indian rubber the 

 product of one tree, gutta percha of another, sago of 

 another; various perfumes from one plant, and dis- 

 agreeable odors from another, as in the rose or the 

 mignionette of one class, the skunk cabbage or the 

 tomato of the other; some also have a pungent or 

 aromatic taste, such as the sassafras and the birch 

 In short the variety of bodies that thus communicate 

 different qualities to plants, or often to the different 

 parts of the same plant, are more numerous than 

 would be believed by one who had not attended some- 

 what to the subject. 



The different oils and sugars, for instance, which 

 exist in vegetables, may be counted by tens and twen- 

 ties already, while new kinds are constantly being 

 discovered; so with the various extracts which can be 

 4* 



