CHEMICAL BASIS OF PLANT FORMS 233 
stituents of Plants considered in Relation to their Morphology 
and Evolution.” 1 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. 
