HIGHER AND LOWER PLANTS 275 



Plate II is a chemical representation, drawn after Heckel's 

 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- 

 sitae, 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- 



