THE CHEMISTRY OF CHLOROPHYLL 445 



mediate between haematoporphyrin and phylloporphyrin. To 

 this they assigned the namemcsoporphyrin. Accepting the formulae 

 of the two former bodies as given above, its composition should 

 be represented by the formula Cg^s^N.,. 



A further relationship between the blood-pigments and chloro- 

 phyll was subsequently discovered by Willstatter, when by the 

 action of acids on rhodophyllin he obtained the substance 

 alloporphyrin, which has almost exactly the same empirical 

 composition as mesoporphyrin, although it differs from it in 

 certain particulars. 1 



Willstatter also demonstrated an intimate relationship in the 

 chemical composition between the magnesium derivative rhodo- 

 phyllin and the iron blood-derivative haemin. 



In addition to mesoporphyrin, Zaleski and Nencki obtained 

 by the reduction of haematoporphyrin, a volatile product which 

 yielded a crystalline picrate and an insoluble mercury compound, 

 and which gave with sulphuric acid and pine splinters the colour 

 reaction which is characteristic of pyrrol derivatives. To this 

 they assigned the formula C 8 H 13 N and designated it haemopyrrol. 

 On standing in air it oxidised to a red substance, which changed 

 to yellow on addition of alkali, and to a pink colour with a 

 beautiful green fluorescence on the addition of an ammoniacal 

 solution of a zinc salt. These reactions are characteristic of the 

 urinary pigment urobilin, the cause of urobilinaria after blood 

 extravasations. 



At this stage of the investigations, Nencki and Marchlewski 

 united in their work, and showed that phyllocyanin, the mother- 

 substance of phylloporphyrin, also yields, on reduction with 

 hydriodic acid and phosphonium iodide, the substance haemo- 

 pyrrol. These investigations established without doubt the 

 intimate chemical relationship between chlorophyll and the 

 blood-pigments. 



The constitution of haemopyrrol has formed the subject of 

 numerous investigations by Kiister, who has shown that it is 

 apparently a mixture of two substances, one of which is more 

 basic than the other. The more acid derivative yields on 

 oxidation an imide which is identical with methyethyl malein- 

 imide. The two substances contained in haemopyrrol are probably 



1 The formula assigned to alloporphyrin in Willstatter's paper is C 33 H 36 4 N 4 . 

 With bodies of this high molecular weight, it is impossible, of course, to obtain the 

 correct formula from the analysis results alone. 



