568 LECTURE XXIV. 



hemato- and phyllo-porphyrin. The following formulae show the close 

 relationship between these last two compounds: 



CH 2 CH 2 



/ \ / \ 



HC C C(OH) (OH)C C CH 



II II I I II II 



HC C CH HC C CH 



NH CH 2 \/^ CH 2 NH 



O 

 Hematoporphyrin: CieHigN^a. 



CH 2 CH 2 

 / \ / \ 

 HC C CH HC C CH 



II II I I I! II 



HC C CH HC C CH 

 \x\/\ X"\/\/ 

 NH CH 2 \X CH 2 NH 



O 

 Phylloporphyrin: Ci6Hi 8 N 2 O. 



Now that we have shown the relations of hematin to chlorophyll, we 

 shall return to the pigment of the blood and describe the products formed 

 from its disintegration. While we are not yet in a position to give a 

 very satisfactory picture of the formation of hemoglobin, or hematin, 

 we are better informed concerning its decomposition products. The red 

 corpuscles are without doubt being constantly destroyed, and thereby 

 hemoglobin is set free. This breaks down,' according to our present 

 knowledge, first into hematin and globin. The latter is probably further 

 decomposed exactly as is usually the case with proteins. A substance 

 which for a long time has been recognized as one of the decomposition 

 products of hematin, is a pigment occurring in the bile which is known 

 as bilirubin, and has the empirical formula Ci6Hi8N 2 3 which corresponds 

 to that of hematoporphyrin^ That, as a matter of fact, these two com- 

 pounds are very closely related to one another has been shown by 

 Kiister, 1 who obtained from bilirubin, by the same methods that were 

 used with hematin, two hematinic acids which correspond to those 

 obtained from hematin. Bilirubin and hematoporphyrin appear to be 

 isomers. The transformation of hematin into the biliary pigment takes 

 place in the cells of the liver. If the blood is injected under the skin of 

 an animal, there will be noticed an elimination of iron at that very spot. 

 The greater part of the blood's pigment, however, will reach the circula- 

 tion and be carried to the liver. Here again the iron is first of all 



1 Z. physiol. Chem. 26, 314 (1898); Ber. 32, 677 (1899); ibid. 35, 1268 (1902); 

 Z. physiol. Chem. 47, 294 (1906). 



