COMPARATIVE CHEMISTRY OF HIGHER AND 

 LOWER PLANTS 1 



ON coming before a popular audience to present a special 

 subject like plant chemistry, I do so in hopes, perhaps, of show- 

 ing some of the less familiar sides of plant life. The chief 

 idea of the remarks I am about to make is one that has not 

 occupied to any great extent the minds of botanists and chem- 

 istSj and if it be not true, at least no other hypothesis has been 

 suggested than the one I shall indicate to account for the 

 chemical compounds of the vegetable kingdom. 



On past occasions 2 1 have spoken of certain chemical com- 

 pounds in relation to plant morphology and evolution. The 

 facts then advanced tended to show a chemical progression 

 in plants, and a mutual dependence between chemical con- 

 stituents and change of vegetable form, and in the following 

 pages I shall keep this idea prominently before you. 



Certain condensations of force on our planet are known 

 as chemical bodies. By usual methods they cannot be split 

 up into component parts, hence are denominated elements. 

 However, we have reason to believe that these so-called 

 elements are in reality themselves compounds, formed in the 

 cosmic laboratory from still simpler aggregations of matter. 



In mineralogy the series of chemical formations are doubt- 



1 Lecture delivered in the course given under the auspices of the Philo- 

 sophical, Anthropological, and Biological Societies in the United States Na- 

 tional Museum, Washington, April 23, 1887. Printed in the American Nat- 

 uralist, August, September, 1887; also in pamphlet form, Philadelphia, 

 1887. 



2 " Certain Chemical Constituents of Plants considered in Relation to their 

 Morphology and Evolution." Read before the Chemical Section of the A. A. 

 A. S. at Buffalo, 1886. Abstract published in the Botanical Gazette, vol. xi, 

 October, 1886. " The Chemical Basis of Plant Forms." Lecture delivered 

 before the Franklin Institute, Philadelphia, 1887. Franklin Institute Journal. 

 See ante, p. 168. 



