ORGANIC ELEMENTS. 5 



tinguish organic from inorganic substances. To the 

 first of these two classes we will now attend. 



The name organic is given, because organic bodies, 

 being products of life, have an organized structure that 

 can not be produced by artificial means. What is 

 meant by an organized structure, may be seen by 

 examining a cross section from the stem of a tree : 

 this will be found to consist of little tubes and cells, all 

 arranged in a regular manner. Under the microscope, 

 a potato will appear made up of cells having grains 

 of starch contained. So with other plants or parts of 

 plants, they all have an organization that is a product 

 of life, and w r hich we therefore can not imitate. In- 

 organic bodies have no such structure, and can in 

 many cases be produced by chemical processes. 



SECTION III. ORGANIC ELEMENTS OF PLANTS. 



The organic part in plants is by far the largest, as 

 is plainly to be seen on burning any form of vegetable 

 matter. It ordinarily constitutes from 90 to 97 lbs. in 

 every hundred. 



During the burning, this solid organic matter dis- 

 appears : it is driven off into the atmosphere, until 

 nothing but a little ash remains; that which has gone, 

 then, has evidently become air. It is easy to see that 

 this part of the plant can only have been formed from 

 air at first. Such a conclusion may seem very strange 

 at first, but a little reflection will show that we can 

 arrive at no other. When we have made up our minds 

 to this, it becomes important to know what kind of air 

 it is that forms so large a part of our plants, or if there 

 is more than one kind. 



These points have been determined through the 

 assistance of certain chemical experiments, by means 

 of which it has been proved that the organic part of 

 plants consists of four substances. 

 1* 



