438 BLOOD AND LYMPH. 



This is made more certain by the fact that hemoglobin is the 

 mother substance from which the bile pigments are made, and, as 

 these pigments are being excreted continually, it is fair to suppose 

 that red corpuscles are as steadily undergoing disintegration in the 

 blood-stream. 



The number of red corpuscles destroyed daily in the body has never been 

 determined with any accuracy, but it may be quite large, as would appear 

 from the following approximate calculation based upon our incomplete 

 knowledge of the amount of bile-pigment secreted daily. From observations 

 made upon cases of biliary fistulas in man it is estimated that the daily flow 

 of bile amounts to about 15 gms. per kilogram of body weight. If we assume 

 in accordance with the figures given by some authors that the bile contains 

 as much as G.2 per cent, of pigment, then 1.95 gms. of pigment will be secreted 

 per day (65 X 15 X. 002). This pigment is formed from approximately the 

 same weight of hematin and for its formation would require the destruction 

 of 48 gms. of hemoglobin, since hematin forms 4 per cent, of the molecule of 

 hemoglobin (1.95-r-.04=48). Abderhalden gives a much more moderate 

 estimate on the assumption that the daily excretion of pigment in the bile 

 amounts only to 0.5 gm. This amount of pigment would be obtained from 12.5 

 gms. of hemoglobin. In order to furnish even as much as 12.5 gms. of hemo- 

 globin, it is evident that an enormous number of red corpuscles, approximately 

 450,000,000,000, would have to be destroyed daily. 



Just when and how the corpuscles go to pieces is not definitely 

 known. It has been suggested that their destruction takes place 

 in the spleen or lymph-glands or in the liver. Certain large cells 

 (macrophags) have been described in the spleen which, at times, 

 contain red blood-corpuscles or fragments of them in their cyto- 

 plasm. In the bird and some other animals Kyes* has been able 

 to demonstrate that the so-called Kupffer cells of the liver actually 

 ingest red corpuscles, and subsequently digest them so as to liber- 

 ate the iron of the hemoglobin in a form that can be detected by 

 microchemical reactions. These Kupffer cells are modified or 

 specialized endothelial cells of the venous capillaries of the liver, 

 and the cells in the spleen which have the same property seem to be 

 of the same type. Kyes proposes for them the name hemophags. 

 The large number of these cells present in the liver, and their action 

 in destroying the red corpuscles and liberating the iron falls in 

 with the known function of the liver in producing an iron-free 

 bile-pigment from the hematin. Whether or not all red corpuscles 

 meet their fate in this way cannot be determined at present. It 

 would seem probable that some undergo hemolysis while in the 

 blood-stream, but the facts given above are the most definite in- 

 formation obtained upon this interesting question. The con- 

 tinual destruction of red corpuscles implies, of course, a continual 

 formation of new ones. It has been shown satisfactorily that in 

 the adult the organ for the production of red corpuscles is the 

 red marrow of bones. In this tissue hematopoiesis, as the process 

 of formation of red corpuscles is termed, goes on continually, the 

 process being much increased after hemorrhages and in certain 



* Kyes, "Internationalen Monatsschrift f. Anat. u. Physiol.," 31, 543, 1914. 



