The Intake of Carbon 197 



bacteria (with marvelously few exceptions l ) familiar 

 as molds, plant parasites, mushrooms, organisms of decay, 

 and of various fermentative processes ; these all require 

 an intake - - from without the body - - of organic carbon 

 nutrients. Organisms which thus obtain their carbon as 

 organic matter, and which have no apparatus for making 

 it from carbon dioxid and water are in the end dependent. 

 Such organisms have also been termed heterotrophic. 

 Green plants are practically alone in being able to make 

 organic matter out of the raw materials, carbon dioxid and 

 water ; they are independent. Conveying the idea that 

 they make organic food somewhere within the body, and 

 in the first instance for their own use, they have been called 

 autotrophic. 



106. Chlorophyllous plants. - - So far as is known, green 

 plants have always supplied the earth with organic matter, 

 including fuel. The leaf-green which they contain is the 

 strongest link binding living things to the sun, - - the one 

 ultimate source of radiant energy available upon the earth. 

 The means whereby this making of organic food is accom- 

 plished is fundamentally important, and requires careful 

 consideration. All living processes and phenomena are 

 important, but since this stands out as the method whereby 

 the world's supply of organic matter is made, the process 

 assumes an interest scarcely second to that of life itself. 



The green or yellow-green color, sometimes partially 

 veiled, is practically universal among plants which we now 

 recognize as possessing the highest type of plant habit 



1 The exceptions consist in a few species of bacteria, subsequently 

 discussed (section 128), whose paltry contribution to the stupendous 

 quantity of organic matter existent is such as to be wholly negligible. 



