CHEMICAL CONSTITUTION OF VEGETABLES. 75 



white worms which the Indians value as a most delicate dish ; finally, 

 the woody part of the mauritia affords excellent timber for building. 

 It is not necessary to enumerate farther the principles produced 

 by vegetables ; we must now study them in reference to their ele- 

 mentary composition. 



CHAPTER II. 



OF THE CHEMICAL CONSTITUTION OF VEGETABLE SUBSTANCES. 



From the very first period of vegetable life, during germination, 

 the immediate principles which constitute the seed are destroyed or 

 changed. The young plant, in developing its organs, creates new 

 substances, which are added to the tissues already existing, so as to 

 complete or extend them. In order to account for the productions 

 or changes which take place in the organism of vegetables, it is ex- 

 pedient first to study the intimate nature and general characters of 

 the materials which compose them. Unfortunately, in the present 

 state of science, this study is as yet but little advanced ; and, not- 

 withstanding the efforts which chemical physiology has made in 

 recent times, there still remain numerous and important questions 

 to be solved. 



Carbon, hydrogen, oxygen, azote, combined in some cases with 

 minute quantities of sulphur or phosphorus, are the only elements 

 required by nature to give rise to that almost endless variety of 

 vegetable substances, so different in their properties, as well as in 

 their uses. In the food which sustains the life of animals, as in the 

 virulent poison which destroys it, these same elementary bodies are 

 always found combined in various and dissimilar proportions. 



The immediate principles of the vegetable kingdom may be 

 divided into three groups, if we look to the number of the elements 

 which constitute these principles as they exist in the several bodies : 



1°. Quarternary^ containing carbon, hydrogen, oxygen, azote. 



2°. Ternary, containing carbon, hydrogen, oxygen. 



3°. Binary, containing carbon and hydrogen, or carbon and oxy- 

 gen, or carbon and azote. 



It is by the examination of the immediate principles which ekist 

 in the seed, that we should approach the study of the composition 

 of vegetables ; and this the more, as we shall find these principles 

 diffused throughout the organs of plants. Once we shall have fully 

 considered their properties and their elementary composition, it will 

 be sufficient merely to indicate where they are to )e met with in 

 the organism. 



