BLOOD PIGMENTS 485 



to bear to chlorophyll,^'^ with wliicli luMiioslobin is so closely rolatod 

 functionally. It is also interesting to consider that whereas carnivora 

 obtain much hemoglobin in their food, herbivora obtain much chlo- 

 rophyll. Pathologically, porphjTin is of interest as a urinary pigment, 

 being found normally in the urine in traces, but present in considerable 

 quantities in many diseases, ^^ such as rheumatism, tuberculosis, 

 various liver diseases, and, most strikingly, after the administration 

 of sulphonal, veronal or trional. A congenital form of hematoporphy- 

 ria occurs, in which the blood contains free hematin and a porphyrin 

 (Schumm),^ about 0.3-0.4 gm. being usually excreted daily in the urine; 

 in the blood it is accompanied by hematin and bilirubin. When in abun- 

 dance it may color the urine a rich Burgundy red, and it is sometimes 

 accompanied by a precursor, uro-fuscin. It is present in the bones of 

 animals showing hemochromatosis and in the bones of persons- 

 exhibiting the congenital form of "hematoporphyria," described by 

 Giinther, which is accompanied by severe skin lesions that are ascribed 

 to the action of light upon the skin sensitized by the hematoporphyrin. 

 Hausmann'' and others have studied extensively the photosensitizing 

 action exhibited by hematoporphyrin and other porphyrins, and find 

 evidence suggesting a relationship between hematoporphyria and 

 " hydroa aestiva," and other conditions in which the skin is abnormally 

 sensitive to light. An acute form of porphyrinuria has been described, 

 usually in women, and sometimes associated with ascending motor 

 paralysis.''" 



Afterinjection of 0.2 gm. hematoporphyrin into his own veins Meyer- 

 Betz'* found himself so sensitized to light that exposure to the sun 

 caused severe skin reactions during a period of weeks, and exposure 

 to the Finsen light produced severe ulceration; but little hemato- 

 porphyrin escaped in the urine. Many other products of blood 

 destruction tested on animals were without sensitizing effects. IVIeth- 

 ylation of the pyrrol groups only partially removes the activity of 

 hematoporphyrin. Porphyrin obtained from urine and feces by Fischer 

 also sensitized mice to light. Sufficient doses of hematoporphyrin 

 may sensitize mice so that they become narcotized and die in a few 

 minutes after exposure to intense light, a true "light stroke." 



Pseudomelanosis. — When loosely bound iron is present in the 

 tissues, and in the same tissues sulphides are produced tlirough bac- 

 terial action, a discoloration with sulphide of iron will result, which is 

 called pseudomelanosis, because the pigment resembles true melanin 

 in its blackness. This is most frequenth'- observed as a postmortem 



'^ For literature see Abderhalden, "Lehrbuch der physiol. Chemie," 1906. 

 95 See Garrod, .Jour, of Physiol., 1892 (13), 598. 



iZeit. physiol. Chem., 1916 (98), 123; 1919 (105), 158. 



' Hegler et al, Deut. med. Woch., 1913 (39), 842. 



= Biochein. Zeit., 1910 (30), 276; 1914 (67). 309. 



3<»L6ttier, Corr.-bl. f. Schweizer Aerzte, 1919 (49), 1871. 



* Deut. Arch. klin. Med., 1913 (112), 476. 



