398 PATHOLOGICAL PIGMENTATION 



has examined a specimen of urine preserved from Hansemann's 

 case, and found no evidence of alkaptonuria. 1 



Pick 2 has recently added another case to the literature, and 

 he summarizes the results of his study of this case and of the 

 literature, as follows : Ochronosis is a definite form of mela- 

 notic pigmentation, the pigment of ochronosis being in most of 

 the cases very closely related to melanin. The pigment, or its 

 chromogen, circulating freely in the blood, is imbibed not only 

 by cartilage, but also by loose connective tissue, voluntary and 

 involuntary muscle-cells, and epithelial cells, without any decrease 

 in vitality of these cells being observable ; however, degenerated 

 tissues show the greatest amount of pigmentation. The diffuse 

 pigment can become granular after a time ; it is iron-free, but 

 under certain circumstances may contain fat. This melanin 

 arises from the aromatic nucleus of the proteid molecule (tyrosin, 

 phenylalanin), and the related hydroxylized products, under the 

 influence of tyrosinase. In two cases the constant absorption 

 of minute quantities of phenol from surgical dressings seems 

 to have been the cause of the condition. Besides this formation 

 of pigment from such " exogenous " aromatic substances, how- 

 ever, it is probable that in alkaptonuria the " endogenous " 

 aromatic substances (alkaptonuric acids) present may be con- 

 verted into pigment by the tyrosinase. In many of the cases 

 of ochronosis the pigment or a precursor may be excreted in the 

 urine, which then undergoes spontaneous darkening when exposed 

 to the air. The kidneys may also become pigmented, and gran- 

 ular masses of pigment may be present in the renal tubules. 



Malarial pigmentation has been studied, particularly by 

 Ewing, 3 who states that in malarial fever one may meet with 

 granular, sometimes crystalline, pigment particles, free in the 

 vessels or englobed in various cells, not giving the Prussian- 

 blue reaction, nor dissolving in chloroform, ether, or carbon 

 bisulphide, but dissolving in ammonium sulphide. This pig- 

 ment may have any one of the following origins : 



(1) Pigment elaborated by the intracellular parasite. (2) 

 Hematoidin derived from the remnants of infected red cells. 

 (3) Hematoidin or altered hemoglobin deposited in granular or 

 crystalline form from red cells dissolved in the plasma. (4) 

 Bilirubin or urobilin granules or crystals. 



Of these, the pigment formed by the parasites has been con- 

 sidered by many as a true melanin, but this cannot be considered 



1 Also see Langstein, Berl. klin. Woch., 1906 (43), 597. 

 2 Berl. klin. Wochenschr. , 1906 (43), 478. 

 3 Jour. Exp. Med., 1902 (6), 119. 



