304 Mr. E, Sclmnck. 



This may, I think, be a suitable place for a few remarks on the 

 somewhat altered sense in which I use the terms phyllocyanin and 

 phylloxanthin, names bestowed by Fremy on what he supposed to be 

 constituents of chlorophyll. In his first memoir on the green colour- 

 ing matter of leaves Fremy* maintained that by acting on chlorophyll 

 with a mixture of ether and hydrochloric acid he had caused it to 

 split up into two colouring matters, one of which passes into the 

 acid, imparting to it a bright blue colour, while the other dissolves in 

 the ether, which it colours yellow, the two together causing by their 

 combined presence the ordinary green colour of leaves and other 

 organs. I need not here refer to the fact, sufficiently manifest to any 

 one who has paid attention to the subject, that Fremy was in error 

 in supposing that his two colouring matters pre-existed as such in 

 the cells of plants, and was not aware that they were, in part at least, 

 products of the decomposition of chlorophyll. I merely wish to 

 remark that the author's two colouring matters must have been, 

 considering the mode of preparation employed, mixtures of several 

 substances, some of which, so far as we know, are not in any way 

 connected with chlorophyll, using the latter term in the stricter sense 

 as being the substance to which the green colour of leaves, &c., is due. 

 At the same time I think it right to say a few words to justify myself 

 in retaining Fremy's names, and at the same time applying them in 

 a somewhat different sense. Returning to Fremy's first experiment 

 with ether and hydrochloric acid, I think I have proved, by what is 

 stated in the first part of this memoir, that the author's blue liquid 

 is in fact a solution in hydrochloric acid of a substance which is a 

 product of decomposition of chlorophyll, This substance I call phyllo- 

 cyanin. It is a weak base, forming with acids unstable compounds 

 of a blue colour, Fremy's phyllocyanin being in fact such a compound. 

 It also combines with bases, though not without at the same time 

 undergoing a change, a description of which is contained in the third 

 part of this memoir. f To have given it another name would prob- 

 ably have led to misunderstanding on the part of those not specially 

 conversant with the subject, and to confusion in its terminology. A 

 similar instance of the retention of name presents itself in the case of 

 the alkaloid Berberin. The berberin of the original discoverer was 

 subsequently found to be the hydrochloride of a base which then 

 retained the name berberin, though not identical with the original 

 substance so called. In his second memoir^ Fremy takes quite 

 another view of the constitution of chlorophyll. Having acted on 

 chlorophyll in alcoholic solution with caustic baryta he obtained an 

 insoluble compound, which he called phyllocyanate of baryta, and 



* ' Comptes Kendus,' vol. 50, p. 405. 

 f ' Eoy. Soc. Proc.,' vol. 44, p. 448. 

 J 'Comptes Kendus,' vol. 61, p. 188. 



