HIGHER AND LOWER PLANTS 259 



our well-established scientific facts would still be buried from 

 sight. 



The chemical analysis of the dead plant and the study of 

 the chemical changes occurring in the living plant are among 

 our means for some of these investigations; and much of all 

 the knowledge derived from each field of chemical research 

 may be utilized in aiding to unravel the mystery of these changes 

 in the vegetable cell. 



In the mineral kingdom certain elements are invariably 

 associated with others, as nickel with cobalt; and in plants 

 not only do we find two or more compounds invariably present 

 together, i. e., tannin and starch in the tannin groups, lime 

 and saponin in the pink family (CaryophyllacecB)^ resins and 

 saponin in all of the saponin-containing groups, and sugar 

 and silica in the grasses (Graminece), but also in certain 

 plant groups we notice the predominance of special com- 

 pounds, and their absence in other groups. The grouping of 

 these compounds in definite association must bear some re- 

 lation to their respective sequence and formation, and cannot 

 be the result of accident. That the cinchona plant does not 

 manufacture the alkaloids of the poppy, but each its own 

 particular series of compounds, illustrates this. 



I have said, elsewhere, 2 "The chemical compounds of plants 

 do not occur at random. Each stage of growth and develop- 

 ment has its own particular chemistry. . . . The result of 

 experiment shows that the presence of certain compounds is 

 essential to the vigor and development of all plants, and par- 

 ticular compounds to the development of certain plants." 

 It may be inferred that "plant chemistry and morphology 

 are related. Future investigation will ^demonstrate this re- 

 lation." 



The theory of evolution, which underlies all mineral and 

 organic forms, comprises the evolution of the component parts 

 of the whole, and since the structural bases of minerals and 

 plants are chemical compounds, their evolution must neces- 



1 Die Pflanzenstoffe, by Hilger and Husemann, p. 542; E. v. Wolff, /. pr 

 Chem., li, 24; lii, 86; Wolff, Aschenanalysen, 1881, pp. 144, 145. 



2 "The Chemical Basis of Plant Forms," p. 232, ante. 



