326 



I pointed out the difficulties in the way of the supposition that these 

 pigments are identical with plant chlorophyll. Recently, Dr. McMunn'^ 

 has also been re-investigating these pigments and has come to the 

 conclusion that they are »derivatives« of chlorophyll, and are produced 

 by the action of the digestive ferments on the chlorophyll of the food. 

 Since the publication of his paper I have made some observations on 

 the derivatives of plant chlorophyll which have yielded somewhat sur- 

 prising results. 



As Dr. McMunn in his previous papers has emphasized the re- 

 semblances between acidified solutions of his entero chlorophyll and 

 of acidified extracts of plant chlorophyll, I determined to investigate 

 the characters of phyllocyanin, the pigment produced by the action of 

 acid on chlorophyll. For this purpose, I used two sets of solutions 1) alco- 

 holic extracts of green leaves, and 2) similar extracts of green Algae 

 (species of Ulva and Enteromorpha] . Into these solutions a current of 

 hydrochloric acid gas was passed in accordance with the directions 

 of Dr. Schunck^. The result in the first case was exactly that 

 described by Dr. Schunck. A dark precipitate fell which increased 

 in amount on standing, and which after purification showed all 

 the characters of phyllocyanin. That is, it contained a pigment in- 

 soluble in cold alcohol and almost insoluble in ether, soluble in acids 

 to form a dark blue solution, and giving a characteristic spectrum. It 

 is obvious that with such a pigment — one quite insoluble in alcohol 

 — the soluble enterochromes can have no near relation. When how- 

 ever hydrochloric acid gas was passed into the extract of green Algae, 

 quite a différent result was obtained. In this case no precipitate fell even 

 after standing, although the solution showed a marked change of colour, 

 becoming a darker shade of green. To this strongly acid solution water 

 was added. There was an instantaneous precipitate of blackish colour, 

 and the solution became deep blue. The same result is attained by 

 adding dilute hydrochloric acid to the original extract, when it depo- 

 sits a blackish precipitate and becomes bright blue. 



The precipitate was washed with water to remove the acid, dried, 

 and treated with cold methylated spirit. In this it dissolves com- 

 pletely to form a greenish-brown solution with brillant red fluores- 

 cence. The spectrum is no longer that of chlorophyll but consists of 

 four bands similar to those of chaetopterin and enterochlorophyll with 

 a trace of fifth band. On adding acid to this solution it turns green, 

 and the band which was previously indistinct becomes quite clear while 



2 Proc. Roy. Soc. London, LXIV. (1899.) p. 436—439. 



3 Ann. of Bot. III. (1889.) p. 65—121, 1 pi. 



