308 



The Formation Oj the Anthocyan Pigments of Plants. 

 Part IV.* — The Chromogens. 



By Frederick Keeble, Sc.D., Professor of Botany, University College, 

 Beading ; E. Frankland Armstrong, D.Sc., Ph.D. ; and W. N. 

 Jones, M.A., Lecturer in Botany, University College, Beading. 



(Communicated by W. Bateson, F.B.S. Beceived February 3, — 

 Bead February 27, 1913.) 



The object of the series of communications of which the present paper 

 forms a part is the elucidation of the biochemistry and genetics of flower- 

 pigmentation. In order to achieve this object it is necessary, in tbe first 

 place, to ascertain the nature of the chemical processes which determine the 

 formation of the anthocyan pigments, and, in the second place, to discover 

 the chemical nature of the Mendelian characters to which the several 

 varieties of a given species owe their power of forming and breeding true to 

 definite types of flower colour. 



The history of the working hypothesis which we use in these investigations 

 has been summarised in an earlier paper.f This hypothesis may be expressed 

 in the form of the equations A and B : — 



A. Prochromogen + enzyme = chromogen. 



? a glucoside. ? emulsin. 

 B. Chromogen + oxydase = anthocyan pigment. 



. A . 



f \ \ 



Beroxydase + organic peroxide. 



Our previous and present communications are concerned with the latter, 

 consideration of equation A being reserved for a subsequent occasion. 



The position to which our previous work has led us may be summarised 

 thus : — 



The presence of oxydase in flowers may be demonstrated by means of 

 benzidine, a-naphthol, or similar " artificial chromogens," which, when acted 



* Previous papers of the series, which did not bear the general title, are : — 



[Part I.] — "The Distribution of Oxydases in Plants and their Rule in the Formation of 

 Pigments," ' Eoy. Soc. Proc.,' 1912, B, vol. 85; [Part II.]— "The Oxydases of Cytisus 

 Adami," 'Eoy. Soc. Proc.,' 1912, B, vol. 85 ; [Part III.]— "The R6le of Oxydases in the 

 Formation of Anthocyan Pigments of Plants," ' Journ. Genetics,' Nov. 1912, vol. 2, No. 3. 



t " The RSle of Oxydases in the Formation of Anthocyan Pigments of Plants," ' Journ. 

 Genetics,' 1912, vol. 2, No. 3. 



