350 THE ORIGIN OF THE BILE COLOURING MATTERS. [BOOK II. 



equation probably expresses the transformation of haematin into 

 bilirubin 



CJiWyre + 2H 2 - Fe = C s fl^Q, 



Hasmatin Bilirubin 



The iron free haematoporphyrin, which, according to Nencki and 

 Sieber, has the same percentage composition as bilirubin, and which 

 is represented by the formula C 16 H 18 N 2 3 , when reduced by means of 

 tin and hydrochloric acid in alcholic solution soon yields a body which 

 confers a yellow colour to the solution, and which in its behaviour 

 towards solvents, and in its spectrum, is undistinguishable from hydro- 

 bilirubin, which we have seen to be the typical product of the action 

 of nascent hydrogen on bilirubin (Hoppe-Seyler 1 ). 



In addition to the above facts, which alone are perhaps sufficient 

 to prove that the bile colouring matters are derived from the haematin 

 of haemoglobin, there are others which tend in the same direction. 

 Thus Amphioxus which is the only vertebrate without red blood 

 corpuscles forms no bile colouring matters (Hoppe-Seyler 2 ). 



Again, it has been shewn that, concurrently with the excretion of 

 the bile colouring matters, the liver always excretes iron, though the 

 amount of the latter is not in proportion to the former, assuming the 

 decomposition to go on, as expressed in the equation of Nencki and 

 Sieber. 



That all the iron, resulting from the decomposition of haematin 

 which leads to the formation of bile colouring matters, should not be 

 excreted in the bile is, however, in no way surprising. The fact, indeed, 

 agrees with others with which we are acquainted. It has already 

 been stated that Zaleski found various combinations of iron in the 

 liver. In some of these the metal can be detected by the reagents 

 usually employed for the detection of iron in its salts (e.g. by 

 potassium ferrocyanide and hydrochloric acid), but in others the 

 metal is an element of organic compounds, such as nucleins, and can 

 only be detected when these are destroyed. In one form or another, 

 the liver appears to hoard a certain proportion of iron which probably 

 takes part in fresh syntheses of haemoglobin. When, however, the 

 destruction of red blood corpuscles goes on with abnormal rapidity, 

 as appears to be the case in pernicious ancemia (Hunter 3 , Mott 4 , 

 Del^pine 5 , and in poisoning by arseniuretted hydrogen (Naunyn 

 and Minkowski 6 ), the iron in the liver increases greatly. In the 

 first case, the urine contains abnormal quantities of urobilinoid 



1 Hoppe-Seyler, Physiologische Chemie, p. 398. 



2 Hoppe-Seyler, Pfluger's Archiv, Vol. xiv. (1877), p. 399; Physiologische Chemie, 

 p. 276. 



3 Hunter, Lancet, 1888, Vol. n. pp. 555, 608, 654. 



4 Mott, Lancet, 1889, Vol. i. p. 520 ; 1890, Vol. i. p. 287 ; Practitioner, Aug. 1890. 



5 Delepine, Practitioner, Aug. 1890. 



6 Minkowski und Naunyn, Archiv f. exp. Pathol. und Pharmakol. Vol. xxi. (1886), 

 p. 1. 



