GENERAL PROPERTIES: THE CORPUSCLES. 413 



has not been determined, nor is it certain where and how they go 

 to pieces. It has been suggested that their destruction takes place 

 in the spleen, but the observations advanced in support of this 

 hypothesis are not very numerous or conclusive. Among the rea- 

 sons given for assuming that the spleen is especially concerned in 

 the destruction of red corpuscles, the most weighty is the histo- 

 logical fact that one can sometimes find in teased preparations of 

 spleen-tissue certain large cells which contain red corpuscles in their 

 cell-substance in various stages of disintegration. It has been 

 supposed that the large cells actually ingest the red corpuscles, 

 selecting those, presumably, that are in a state of physiological de- 

 cline. Against this idea a number of objections may be raised. 

 Large leucocytes with red corpuscles in their interior are not found 

 so frequently nor so constantly in the spleen as we should expect 

 would be the case if the act of ingestion were constantly going on. 

 There is some reason for believing, indeed, that the whole act of 

 ingestion may be a postmortem phenomenon; that is, after the 

 cessation of the blood-stream the ameboid movements of the large 

 leucocytes continue, while the red corpuscles lie at rest, conditions 

 that are favorable to the act of ingestion. It ma} 7 be added also 

 that the blood of the splenic vein contains no hemoglobin in solu- 

 tion, indicating that no considerable dissolution of red corpuscles ia 

 taking place in the spleen. Moreover, complete extirpation of the 

 spleen does not seem to lessen materially the normal destruction 

 of red corpuscles, if we may measure the extent of that normal 

 destruction by the quantity of bile pigment formed in the liver, 

 remembering that hemoglobin is the mother-substance from which 

 the bile pigments are derived. It is more probable that there is no 

 special organ or tissue charged with the function of destroying red 

 corpuscles, but that they undergo disintegration and dissolution 

 while in the blood-stream and in any part of the circulation, the 

 liberated hemoglobin being carried to the liver and excreted in part 

 as bile pigment. The continual 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 reproduction 

 of red corpuscles is the red marrow of bones. In this tissue hema- 

 topoiesis, as the process of formation of red corpuscles is termed, goee 

 on continually, the process being much increased after hemorrhages 

 and in certain pathological conditions. The details of the histo- 

 logical changes will be found in the text-books of histology. It is 

 sufficient here to state simply that groups of nucleated, colorless 

 cells, erythroblasts, are found in the red marrow. These cells 

 multiply by karyokinesis and the daughter-cells eventually produce 

 hemoglobin in their cytoplasm, thus forming nucleated red cor- 

 puscles. The nuclei are subsequently lost, either by disintegration 



