258 PLANT AND ORGANIC CHEMISTRY 
less the result of evolution from the more simple elements to 
the complex structure of the crystalline rocks. 1 
The plant kingdom may be considered as a third and 
higher stage; it contains in its structure combinations of the 
elements carbon, hydrogen, nitrogen, oxygen, sulphur, phos¬ 
phorus, and compounds derived from the mineral world. 
The essence which underlies all force and life may be traced 
through these three planes as a law of progression, little 
varying in its general course, though ever giving more involved 
problems for solution, according to the increasing complexity, 
from elements and minerals to plants, and even to animals. 
The line separating each of these conditions of matter is 
indistinct, “the individual of the one encroaches upon the 
dominion of the other; ” 2 as a spiral coil is of a single thread, 
so “nature in all her manifestations constitutes a unity,” 3 
and the rounds of the spiral present each stage parallel, but 
in reality a continuation. 
Analogies should not be given too much weight, but from 
numerous facts the above statements seem theoretically 
reasonable and may be provisionally accepted. The possi¬ 
bility of chemical evolution of the elements, in itself, is not 
only one of the most absorbing questions of the moment for 
investigation, but the evolution of compounds from these 
elements and their possible influence upon the external forms 
of plants is of equal interest. 
That directive force which controls the different groupings 
of atoms in a molecule under the solid, liquid, or gaseous 
forms of matter, manifests itself in still more complicated 
conditions in each grade of the chemical compounds of living 
cells, and thus, from the single cell to the highest of plants, is 
ever active. 
It is not my wish to claim for plant chemistry more than 
the facts at my disposal will allow; though in the past, — and 
this should not be overlooked, — without the aid of the imagi¬ 
nation to penetrate the avenues of the unknown, many of 
1 Mineral Physiology and Physiography, by T. Sterry Hunt, Boston, 1886. 
2 The Chemical Basis of Plant Forms , p. 232. 
3 T. Sterry Hunt, p. 18. 
