Colouring-matters of the so-called Bile of Invertebrates, Src. 391 



was coagulated by absolute alcohol, and thrown on a filter, the mass on 

 the filter exhausted with it, the faintly green filtrate evaporated at a 

 gentle heat. When the residue was extracted with alcohol, and the 

 latter treated with nitric acid after proper dilution, the above reaction 

 and the spectrum of Gmelin's reaction could be made out easily. It is 

 a well-known fact that nitric acid will lead to erroneous conclusions 

 when added to an alcoholic solution of bile-pigments, but the spectro- 

 scope always shows whether the colour reaction is due to bile-pigment 

 or not. As well as I could make out, the band before D extended 

 from \620 — 596, that after D faded quickly away, that at F read from 

 X511 — 494. By the action of oxidising and reducing agents I found 

 that the pigment present could have been nothing else but biliverdin. 



In this case no jaundice was present and the only source from 

 which the biliverdin could have been derived was haemoglobin, which 

 was first converted into methaemoglobin, then into the pigment inter- 

 mediate between that and haematin, and finally into biliverdin. This 

 transformation was probably one of gradual oxidation, assisted by the 

 action of a ferment, which is doubtless present in hydrocele liquid. 

 That a ferment is present in the testis is probable, as Berthelot has 

 prepared glucose by rubbing up testicular tissue, glycerine, and man- 

 nite together. The " haematochlorin "•* of the placenta of the bitch is 

 probably formed in a similar manner. 



Identity of Stercobilin and Hydrobilirubin; Differences from Uro- 

 bilin of Urine. — The spectra of solutions of hydrobilirubin prepared 

 by the action of sodium amalgam on bilirubin have been already 

 described. f I have again prepared it, and find no differences in 

 the characters of the pigment from those which I described ; but I 

 have to call attention to Chart II, sp. 14, of my former paper, which 

 represents an alcoholic solution of hydrobilirubin treated with caustic 

 soda. In that spectrum a band is shown touching C and placed 

 between that line and D, another at D, and a third from. b to near F. 

 I now find the very same bands in an alcoholic extract of the faeces of 

 the cat, after treatment with caustic soda. They were also seen in 

 extracts of gall-stones, as I have previously stated, but these bands are 

 not found in an alcoholic solution of urobilin from urine wlien treated 

 with caustic soda. Hence if the urobilin of urine is derived from the 

 hydrobilirubin of the intestine, it has undergone some change after 

 leaving the intestine (by absorption). 



An alcoholic solution of cat's faeces X shows the band at F with great 

 distinctness from* \505 — 484, and after treatment with caustic soda, 

 the orange solution became more yellow and gave a less refrangible 

 band from X516 — 500 in a shallow layer, but in a deep one that 



* Preyer, " Die Blutkrystalle." 



f " Proc. Roy. Soc," 1880, vol. 31, p. 206. 



X Removed after death from large intestine. 



