﻿12 The Neiv York State College of Forestry 



portions of plants. The basis of all life, be it plant or animal, 

 is that living substance known as protoplasm, and protoplasm 

 requires carbon for its nutrition. In fact carbon is one of the 

 essential constituent elements of that substance. But free car- 

 bon in any of the forms in which it occurs in nature cannot be 

 directly assimilated by plants. Nor is the carbon dioxide w^hich 

 results from combustion absorbed directly in the processes of 

 metabolism. It is first combined chemically in the plant tissues 

 with hydrogen to form sugar or starch. Subsequently other 

 organic compounds are elaborated from these by the protoplasm 

 through a readjustment of molecules, and hence molecular weight, 

 and by the addition of other elements such as nitrogen, sulphur, 

 phosphorus, etc. The ultimate origin of all the organic com- 

 pounds which are found in nature is in the green parts of plants. 

 Plants possess the ability which animals lack of manufacturing 

 complex organic compounds from carbon dioxide and water. 



The gulf which separates the higher plants from the higher 

 animals is obvious — so obvious in fact that one can never mis- 

 take the one for the other. The animal possesses motility; it has 

 a highly developed nervous and circulatory system. Its tissues, 

 aside from the bones, are soft and plastic. It is wholly dependent 

 for its food on compounds elaborated by plants or, in the case 

 of carnivores, in the bodies of other animals. The plant, on the 

 other hand, is compelled to spend its whole life in one place. It 

 lacks a nervous system and while there is a circulatory system 

 this is less specialized, and utilized wholly in the movement of 

 plant foods and water. Its tissues are firmer than those of the 

 animal and differ in their chemical composition. The plant pos- 

 sesses leaves which contain the green pigment chlorophyll, thus 

 permitting it to manufacture its own organic food. 



But science tells us that the higher plants and animals have 

 been derived from low-er, less complex forms, the simplest of 

 which are unicellular. Some of these simple plants are motile. 

 Others, as the bacteria and fungi, are without the green pigment 

 chlorophyll. The simple animals lack a nervous sj^stem worthy 

 of the name and manj- engulf or swallow their food bodily. 

 Others possess chlorophyll granules whose origin is still a matter 

 of dispute. We are forced to the conclusion that there is no 

 sharp dividing line between plants and animals. Differences 

 which obviousl.y se])arate the higher plants from the higher 

 animals will no longer suffice. The simple forms of plants and 

 animals intergrade. 



