231 



ters extracted from the gall, and their derivatives, whieh, with the 

 exceptiün of urobilin, do not cause any cliaracteristic absorption in 

 the visible part of the spectrum, will cause in the more refran- 

 gible part bands. similiar to Chlorophyll and haenioglobin or their 

 derivatives. Our investigations do not confirai this supposition. 



Neither bilirubin. or urobilin and biliverdin stiidied in various 

 solvents cause any cbaracteristic absorpticjn bands in the ultraviolet. 

 Proteinchrom which might be, according to Nencki's hypothesis, the 

 mothersubstance of the blood colouring matter behaved similarly. 

 This resuit alters, to a certain extent, the conclusions drawn from 

 the very important researches of Hartley. It seems that the aljsorp- 

 tion of ultraviolet rays does not in the first instance dépend upon 

 the constitution of the nucleus forming the base of complicated 

 substances, but is caused rather by certain atomic groups, vyhich 

 may not be présent in ail the derivatives of the same mothersub- 

 stance. This explains the totally différent behaviour of urobilin and 

 phylloporphyrin or haematoporphyrin. The next conclusion to be 

 drawn is that urobilin, which is formed so easily by oxidation of 

 haemopyrrolline, obtained from haematoporphyrin or phyllocyanin, 

 and also the other gall colouring matters, must differ constitutio- 

 nally far more from the cliromogen of the blood colouring matter, 

 than does the latter from Chlorophyll. 



The photographs, reproductions of which accompany this papcr, 

 were obtained with an apparatus constructed by A. Hilger of Lon- 

 don. A train of two quartz lenses and an Iceland spar prism were 

 used. The solutions were placed in a cell with quartz facings. The 

 source of light was an Auer-Welsbach burner, the photographie 

 plates were the lightening plates of Messrs. Cadett and Neal of Sur- 

 rey, England. 



The material. Bilirubin and biliverdin were procured from 

 E. Merck, urobilin we made ourselves by Hoppe-Seylers method, 

 or by oxidation of haemopyrroline obtained from phyllocyanin, pro- 

 teinchrom, by selfdigestion of pancreatic glands according to Kura- 

 jefFs prescription. 



The resuit s. Bilirubin which, as is well known, is very 

 imperfectly soluble in alcohol bas been studied in chloroformic so- 

 lutions and also in alcoholic alkaline. Various photographs dis- 

 elosed no cbaracteristic absorption bands in the ulti-aviolet but only 



