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Mr. W. N. Jones. The Formation of the [Feb. 4, 



once in those parts of the flower which contain peroxydase. Hence it is 

 demonstrated that the petals of Lychnis contain a chromogen, which, when 

 extracted from the flowers, is acted on by the peroxydase contained in the 

 petals and gives rise to a red-brown pigment. The peroxydases of Primula, 

 sinensis, Primula obconica, Dianthus sp., etc., were shown also to bring about 

 — in the presence of hydrogen peroxide — an oxidation of the chromogen 

 extracted from the petals of Lychnis. A similar chromogen has been 

 extracted from the white-flowered variety of Anemone japonica. Like that 

 obtained from the flower of Lychnis coronaria, it yields pigments when acted 

 on by the oxydases of petals of various plants. 



The white flowers of e.g. Lychnis coronaria thus yield an extract which 

 can be used to demonstrate the distribution of oxydases in place of a 

 benzidine solution. 



The experiments show, moreover, that these flowers of Lychnis coronaria, 

 although they are white, contain both oxydase and chromogen.* It is 

 therefore probable that these constituents are located in different cells or 

 parts of the same cell, and that whiteness is due to the fact that the plant 

 lacks the means of bringing chromogen and oxydase into contact with one 

 another. 



As has been mentioned already, the pigment obtained by the action of 

 the peroxydase of the petals of Lychnis coronaria on the chromogen extracted 

 from these petals is of a reddish-brown colour. It might, therefore, be 

 urged that the chromogen which gives rise to this pigment is not that which 

 in coloured flowers yields the red anthocyan pigment of the natural petals. 



The objection is weighty ; but that it may be met is shown by the 

 following considerations and experiments : — 



1. It is known that changes in the chemical nature of the chromogen, the 

 degree of oxidation, f the conditions under which the reactions occur, and the 

 presence of traces of other substances,* affect the colour of the end product of 

 oxidation. Too much weight, therefore, should not be attached to mere 

 difference in colour as the colour is very susceptible to alteration. 



* Since browning of the fresh petal occurs under the influence of alcohol alone, the 

 body that behaves as a peroxydase towards e.g. a-naphthol, can behave as an oxydase 

 towards the natural chromogen. 



t In this connection it may be noted that if a pink bract of Bilbergia sp. be immersed 

 in H 2 2 , the pink pigment becomes changed into brown, presumably as the result of 

 further oxidation. In ' U.S. Dept. of Agric. Bureau of Plant Industry Bulletin,' 

 No. 264, 1913 (received as the present paper goes to press), H. H. Bartlett records a red 

 pigment of Dioscorea as becoming brown on oxidation. 



| Chodat, K. "Nouvelles Becherches sur les Ferments Oxydants. Les matieres 

 proteiques et leurs derives en presence du reactif ^D-cresol tyrosinase." ' Arch. Sci. Phys. 

 Nat.,' 1912 (IV), vol. 33, pp. 70, 225. 



