A REVIEW OF WILLSTÄTTER'S RESEARCHES ON 



CHLOROPHYLL^ 



CLARENCE J. WEST 



Introduction. Chlorophyll, as is well known, is the green 

 coloring matter in plants and leaves. Accompanying it are two 

 yellow pigments, Carotin and xanthophyll. 



The history of Chlorophyll and its chemical investigation date 

 back to Berzelius,^ who first attempted to isolate the pigment from 

 leaves. Thinking that it was not affected by conc. hydrochloric 

 acid or alkali sol, he treated the alcoholic extract so vigorously that 

 he obtained only decomposition products. He believed that the 

 green substance was neither a resin, a wax nor a fat but a dyestuff. 

 Since that time much has been published concerning the chemistry 

 of chloroph3dl, a great deal of the work being based lipon investi- 

 gations with the spectroscope/'^ but no consistent chemical investiga- 

 tion had been carried out prior to the work of Willstätter and his 

 co-workers. 



Chlorophyll is probably present in the leaf in a colloidal form, 

 or as a product of adsorption with colloids, which may be extracted 

 under definite conditions with certain organic solvents because of 

 their dissociating powers. This conclusion is based upon the fact 

 that the spectra of different leaves agree with that of colloidal Solu- 

 tions of pure Chlorophyll, though differing in intensity.^ The idea 

 that Chlorophyll is chemically bound in the leaf, with lipoids, for 

 example, is erroneous.^ 



1 This review is based upon the recent book, Untersuchungen über Chloro- 

 phyll, by Richard Willstätter and Arthur Stoll; and also upon the numerous 

 articles published by Willstätter in the Annalen der Chemie. 



2 Berzelius : Ann. d. Chem., 27, 296 (1839). 



2 References may be found in Marchlewski : Die Chemie der Chlorophylle 

 (Braunschweig, 1909). 



* Herlitzka : Biochem. Zeit., 38, 321 (1912). 



5 Hoppe-Seyler : Zeit. f. physiol. Chem., 3, 339 (1879). Stoklasa: Ber. d. 

 deutsch, hotan. Ges., 26, 69 (1907) ; 27, 10 (1909). 



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