Colouring-matters of the so-called Bile of Invertebrates, <J-c. o89 



duced in urine by boiling with, bydrocbloric acid has a similar absorp- 

 tive power for the violet and blue. It is certainly worthy of remark 

 that chlorophyll in plants, and haemoglobin, tetronerythrin, lutein, 

 and bilirubin in animals, should have this property. 



Biliverdin has much the same optical characters as bilirubin, except 

 that more green is transmitted. 



The brownish-green alcoholic solution of biliprasin was found to 

 absorb in a deep layer the spectrum up to three-fourths the distance 

 from D to E, but the edge of the shading was not abrupt, but 

 gradually shaded off towards red. It gave the spectrum of Grmelin's 

 reaction when treated with nitric acid; and with caustic soda a 

 peculiar shading or feeble band became detached, placed midway 

 between D and E. The yellow-brown alcoholic solution of bilifuscin 

 gave a similar spectrum, and behaved similarly as regards spectrum 

 with nitric acid and with caustic soda. 



Bilihumin when dissolved in alcohol formed a dirty brownish-green 

 solution, which had the same optical properties as the last two 

 colouring-matters. It became yellow-brown with caustic soda, and 

 gave the band already described. It also gave Gmelin's reaction. 



Bile Spectra of various Animals. — I have already drawn attention to 

 the peculiar series of bands seen in the bile of certain animals, and 

 shown that they are probably due to the presence of altered heematins.* 

 I have examined since then the bile of the tortoise, mud turtle, 

 common ringed snake, and cormorant, but could detect no bands. 

 During hibernation no urobilin could be detected in the bile of the reptiles. 

 I have succeeded in detecting this colouring- matter in the alcoholic 

 extract of the liver of Salamandra maculata in greater quantity than 

 can be accounted for on the supposition that it was present in the 

 blood-vessels of the liver, and this indicates that urobilin is probably 

 formed in that organ. I shall show further on there are reasons for 

 supposing that the hydrobilirubin in the intestine differs somewhat 

 from the urobilins of urine. In the liver of the toad, frog, newt, 

 tortoise, ringed snake, and mud turtle, as well as in that of the pig, 

 cat. guinea-pig, rabbit, and man, I can find no urobilin in the alcohol 

 extract, probably for the same reasons that other chemical compounds 

 which are known to be formed in that organ cannot be detected in its 

 extract, namely, that they are removed as soon as formed. f The 

 alcohol extract of the above-mentioned livers generally showed the 

 lutein spectrum. In the alcohol extract of the liver of a little fish, 

 which I believe was Blennius pholis, abundance of tetronerytherin was 



* " Spectroscope in Medicine," 1880, and " Proc. Eoy. Soc," 1880, vol. 31, p. 2fi. 

 It is a very interesting fact that the bile of Pulmonate Mollusca and of Astacus f. 

 should contain reduced hsematin like that of certain mammalia in which I have 

 found it, as already communicated to the Royal Society. 



f I have found hydrobihrubin in the faeces of the frog and salamander. 



