CHEMICAL BASIS OF PLANT FORMS 233 



stituents of Plants considered in Relation to their Morphology 

 and Evolution." L The facts cited tended to show a chemical 

 progression in plants, and a mutual dependence between chem- 

 ical constituents and change of form. 

 Among the conclusions reached were the following: 



1. A similarity of one or more chemical constituents is to 

 be found in all plants which are equally developed, and on the 

 same evolutionary plane. 



2. The evolution of chemical constituents follows parallel 

 lines with the evolutionary course of plant forms, the one 

 being intimately connected with the other, and consequently 

 chemical constituents are indicative of the height of the scale 

 of progression, and are essentially appropriate for a basis of 

 botanical classification; in other words, the theory of evolu- 

 tion in plant life is best illustrated by the chemical constituents 

 of vegetable forms. 



Chemistry will aid us to comprehend the laws of evolution 

 controlling plant forms. Evolution should also apply to chem- 

 ical compounds as well as to morphology, since the latter can 

 be shown to depend upon chemistry in general. 



We have no certain knowledge of the precise chemical changes 

 which take place in transforming carbon, hydrogen, oxygen, 

 nitrogen, sulphur and other elements into the starches and 

 proteids. We know, however, certainly the necessary condi- 

 tions for many of these changes. The law controlling the ab- 

 solute relation, or the connective link, between the form of a 

 plant and its chemical composition is undetermined. But in- 

 vestigations in plant chemistry have not been conducted with 

 this end in view. The facts which I have to offer, to sustain the 

 theory of a possible relation between plant forms and chemical 

 compounds, may seem to some inadequate, but no other expla- 

 nation than the one offered to account for these statements has 

 been suggested. 



The chemical composition of the cell-contents and wall has 

 been determined in many plants; also of their roots, leaves, 

 flowers, and fruits. 



1 Chem. Section A. A. A. Science, Buffalo, 1886. Abstract, Botanical Gazette, 

 xi, No. 10, October, 1886. See p. 168. 



