CHEMICAL EXAMINATION OF THE BLOOD. 355 



Hsematoporphyrin is isOmeric with bilirubin. On reduction it 

 yields a pigment which is apparently identical with Maly's hydro- 

 bilirubin and Jaffe's urobilin. It may be obtained in crystalline 

 form as a hydrochlorate, while the pigment itself is amorphous. Its 

 solutions in acid alcohol present a beautiful purple color, which is 

 changed to a violet blue on adding an excess of the acid. It is 

 most conveniently obtained by starting with hsemin and decomposing 

 this with glacial acetic acid that has been saturated with hydro- 

 bromic acid. Its solutions in acid alcohol give two bands of absorp- 

 tion. One of these is located between C and D, while the second 

 band, which is much darker and more strongly defined, occupies 

 a position midway between D and E, and extends as a shadow 

 toward D. In dilute alkaline solutions, on the other hand, we find 

 four bands : one between C and D ; a second one, which is broader 

 than the first, between D and E and about D ; a third band, 

 between D and E, near E ; and finally a further band between b and 

 F, which is the widest and much darker than the rest. On treating 

 with an alkaline solution of zinc chloride this spectrum gradually 

 passes into a new spectrum with only two bands, of which one is 

 seen about D, and the other between D and E. 



The transformation of acid hnematoporphyrin to the alkaline form 

 can be readily effected by oversaturating a solution of haBmatopor- 

 phyrin in sulphuric acid with pyridin ; the garnet color changes to a 

 chestnut, while the solution remains perfectly clear. 



On oxidation hsematoporphyrin yields the same hsematinic acids 

 as haamatin (see above). The resulting tribasic acid, C 8 H 8 O 5 , on 

 reduction with hydriodic acid is transformed into the tribasic ha3mo- 

 tricarbonic acid, C 8 H 12 O 6 ; this is possibly identical with ethyl- 

 tricarballylic acid, which has been obtained synthetically. 



Closely related to haematoporphyrin, apparently, is the phyllopor- 

 phyrin which may be obtained from the chlorophyl of plants. 

 From its formula, C 1(? H 1S N 2 O, and that of haematoporphyrin, C 16 H 18 - 

 N 2 O 3 , it is suggested that both are different oxidation-products of 

 one and the same substance. On reduction with phosphonium 

 iodide in glacial acetic acid hsematoporphyrin yields a product of 

 the composition C 16 H 18 N 2 O 2 , which Nencki and Saleski designate 

 as mesoporphyrin. This manifestly occupies a position inter- 

 mediate between hsematoporphyrin and phylloporphyrin. On 

 still further reduction methyl-propyl-pyrrol is obtained (see Hsema- 

 tin), and it is noteworthy that the same body has also been obtained 

 in the same manner from phylloporphyrin. We see that the prin- 

 cipal animal pigment is thus intimately related to the principal pig- 

 ment of the higher plants. The spectra of haematoporphyrin, meso- 

 porphyrin, and phylloporphyrin are very similar ; they differ from 

 one another by only a slight displacement of all bands in one direction. 



Haematoidin. This pigment, which was first observed by Vir- 

 chow in old extravasations of blood, in which it may occur in crystal- 

 line form, is now known to be identical with bilirubin. As a separate 

 substance it therefore no longer merits consideration, 



