HIGHER AND LOWER PLANTS 
275 
Plate II is a chemical representation, drawn after HeckePs 
botanical table, and, from what has preceded it, will be easily 
comprehended. It is not to be inferred that all classes of chem¬ 
ical compounds found in plants are represented, since only a 
few have been used for illustration, nor that all of these given 
compounds occur only in the designated plant groups, since 
they may occur in traces, or varying quantities, elsewhere. 
However, these compounds are conspicuous as being especially 
typical of the plant groups which correspond to their location, 
and where their presence is doubtless associated with the plant’s 
evolution. 
The chemical compounds which may be said to be typical 
of an order, species, or an individual member of a series would 
be out of place in this general presentation. 
Some plant groups, as the Proteaceae, orchids, and Compo- 
sitse, develop in aesthetic beauty at the expense of their chemi¬ 
cal constituents,—all resources go to develop the perfection of 
the flower, and the absence of numerous compounds in these 
plants is a strong point in favor of chemical evolution favoring 
plant development. These beautiful plants, being among the 
highest of their series, may well be called the aristocrats of the 
vegetable kingdom. 
It is still impossible to demonstrate the full significance of 
this chemical theory in plant development, but it will be evident 
to any one who examines botanical and chemical facts that the 
presence of certain chemical compounds is associated with cer¬ 
tain botanical conditions, and where these conditions are va¬ 
riable, is found a like variability of chemical composition. If it 
can be proved that chemical and botanical morphology are not 
one and the same, at least the two are very intimately corre¬ 
lated. 
It has been said that many of the constituents found in plants 
are the result of destructive metabolism, and are of no further 
use in the plant’s economy, but our knowledge of what consti¬ 
tute plastic and waste products is by no means settled, and even 
should we be forced to accept the conclusion that some pro¬ 
ducts are of no use to the plant, yet it is a significant fact that 
certain cell-tissues or organs secrete or excrete chemical com- 
