HIGHER AND LOWER PLANTS 279 



tend to be what they are not. When will all of these intricacies 

 of nature's secrets belong to commonplace facts ? The day is 

 distant. And in the meantime my hour is drawing to a close; 

 and, to return to my first statement of the evolution of the chem- 

 ical elements, I would say that the studies * of Lecoq de Bois- 

 baudron, Auer, Demarcay, and Crookes on didymium, and the 

 latter' s researches on yttria, and more recently on the crimson 

 line of phosphorescent alumina, 2 go to show that the mole- 

 cules of these so-called elements are compound, and if I have 

 dwelt at all upon this subject, in connection with plant life, it 

 is on account of the indisputably serious nature of the inves- 

 tigations in this field. The following concluding remarks of 

 Professor Crookes' s address 3 show that the theory of the 

 chemical evolution of plant compounds has an able ally. He 

 says, " We cannot venture to assert positively that our so-called 

 elements have been evolved from one primordial matter, but we 

 may contend that the balance of evidence . . . fairly weighs 

 in favor of this speculation. . . . The doctrine of evolution, as 

 you well know, has thrown a new light upon and given a new 

 impulse to every department of biology, leading us, may we 

 not hope, to anticipate a corresponding wakening light in the 

 domain of chemistry. I would ask investigators not neces- 

 sarily either to accept or reject the hypothesis of chemical 

 evolution, but to treat it as a provisional hypothesis; to keep 

 it in view in their researches, to inquire how far it lends 

 itself to the interpretation of the phenomena observed, and to 

 test experimentally every line of thought which points in this 

 direction." 



From the above sketch I have attempted to show that the 

 hypothesis of evolution may also apply to the chemistry of plant 

 compounds, and that plant chemistry will be found, like any 

 special study, to include many others. It is, however, excep- 

 tional in its broad range, and the variety of its topics, like the 

 variations of flower-species, may be cultivated to suit the taste 

 of the investigator. 



1 Comp. Rend., t. civ, 1887, p. 165, M. Henri Besquerel. 



2 Chem. News, Jan. 21, 1887. 



8 Delivered before the British A. A. S., 1886. 



