QuiNLAN — On Spectroscopic Estimation of Bile. 275 



haemorrhagic product, in the urine ; and its spectrum requires atten- 

 tion and comparison. Arterial blood, in the thin layer of solution, 

 absorbs a small portion of the violet end, and venous blood still more ; 

 but in arterial blood we find the two well-known oxyhaemoglobin 

 absorptive lines between D and E, and in venous blood the equally 

 well-known single dark absorption line of reduced haemoglobin 

 nearer the red. Blood, moreover, has a very slight but distinct ab- 

 sorptive power in the red end. Bile, as I have mentioned before, only 

 absorbs the violet end, has no separate absorption lines, and does not 

 in the least affect the red. The microscopical and chemical detection 

 of blood is easy ; but, even with the spectroscope alone, there is no 

 difficulty in this differentiation ; and I have again and again detected 

 the blood lines (either arterial or venous) in instances where blood 

 became accidentally mixed with the bile in the process of removal. 

 The bile absorption (in solutions of equal strength) overlaps the blood 

 (violet) absorption ; and there is no difficulty in detecting both blood 

 and bile in the same specimen ; for accuracy, however, pure solutions of 

 either are preferable. Diabetic sugar or the crystalloids have no effect 

 whatever on the solar spectrum. 



It is now believed by physiologists that the source of the colouring 

 matter of the bile is the disintegration of the red corpuscles which 

 takes place in the spleen. This belief is principally founded on the 

 fact that the injection of haemoglobin into the blood-vessels of a living 

 animal causes a great effusion of bile colouring matter into the urine, 

 and increases the quantity of Bilirubin in the bile. It appears to me 

 that the fact of haemoglobin, in addition to its characteristic absorp- 

 tive bands, absorbing the violet end of the spectrum like bile, is confi.r- 

 matory of the present physiological view as to the nature of bile 

 colouring matter. 



Nothing could be more unlike the yolk of an egg, rich in proteids, 

 than the bile, which contains none ; and yet it has always appeared 

 to me that there was a certain similarity between the golden-coloured 

 bile and the golden yellow colouring matter of the yolk ; and I have 

 long thought both were derived from disintegrated haemoglobin. 

 On applying my test to the yolk, emulsified with three times its 

 own quantity of water, I find it has an absorption nearly identical 

 with that of bile. The yolk, so treated, absorbs 2° 5' of the violet 

 end of the spectrum, and without absorption bands. Here we have 

 an interesting chain of reasoning. "We cannot synthetically make 

 Bilirubin, but we can do so indirectly by injecting haemoglobin into 

 the blood of a living animal, and thus produce a haemoglobin deriva- 

 tive, which will absorb the violet. Does it not seem possible that the 

 colouring matter of the yolk is a similar haemoglobin derivative ? 



I make this suggestion, however, in a purely tentative spirit, and 

 without in the least expressing 'an opinion as to its accuracy or other- 

 wise. In this communication I wish to confine myself strictly to my 

 bile test. The conclusions which appear derivable from it are as 

 follow : — 



