256 PLANT AND ORGANIC CHEMISTRY 



in the plant's economy. This subject is by no means settled, 

 and even should we be forced to accept that ground, it is a sig- 

 nificant fact that certain cells, tissues, or organs peculiar to a 

 plant secrete or excrete chemical compounds peculiar to them, 

 which are to be found in one family, or in species closely al- 

 lied to it. 



It is a fact that the chemical compounds are there, no mat- 

 ter why or whence they came. They will serve our purposes 

 of study and classification. 



The result of experiment shows that the presence of certain 

 compounds is essential to the vigor and development of all 

 plants, and particular compounds to the development of cer- 

 tain plants. Plant chemistry and morphology are related. Fu- 

 ture investigations will demonstrate this relation. 



In general terms, we may say that amides and carbohy- 

 drates are utilized in the manufacture of proteids. Organic 

 acids cause a turgescence of cells. Glucosides may be a form 

 of reserve food material. 



Resins and waxes may serve only as protection to the surfaces 

 of plants ; coloring- matters, as screens to shut off or admit cer- 

 tain of the sun's rays; but we are still far from penetrating the 

 mystery of life. 



A simple plant does what animals more highly endowed can- 

 not do. From simplest substances they manufacture the most 

 complex. We owe our existence to plants, as they do theirs to 

 the air and soil. 



The elements carbon, oxygen, hydrogen, and nitrogen pass 

 through a cycle of changes from simple inorganic substances to 

 the complex compounds of the living cell. Upon the decomposi- 

 tion of these bodies the elements return to their original state. 

 During this transition those properties of protoplasm which 

 were mentioned at the beginning, in turn, follow their path. 

 From germination to death this course appears like a crescent, 

 the other half of the circle closed from view. Where chemistry 

 begins and ends it is difficult to say. 



