12 DECAY OF T1IK ItED BLOOD-CORPUSCLES. 



(C) Later Formation. Most observers agree that the red blood-corpuscles are 

 formed from special nucleated cells, which gradually assume the form and colour of 

 the perfect red corpuscle. According to Neumann, however, these corpuscles are 

 pigmented from the first. In the tailed amphibians and fishes, the spleen, in all 

 other vertebrates the red marrow of bone, are the seats of formation of these 

 corpuscles, which subsequently increase by division (Neumann, Rindjleixch. 

 BuBoeero). In the red marrow of bone we can study all the stages of the transforma- 

 tion ; especially pale contractile cells similar to colourless corpuscles, and also red 

 nucleated corpuscles, which are similar to the nucleated corpuscles of the embryo, 

 and the progenitors of the red corpuscles. These transition cells are said by Erb to 

 be more numerous after severe hemorrhage, the number of them occurring in the 

 blood corresponding with the energy of the formative process. After copious 

 haemorrhage, these transition forms appear in numbers in the blood-stream. The 

 small veins, and, perhaps, the capillaries of the red marrow of bone and the spleen 

 have no proper walls, so that the red corpuscles when formed can pass into the 

 circulation. 



Red oi' blood-forming marrow occurs in the bones of the skull, and in most of the bones of 

 the trunk, while the bones of the extremities either contain yellow marrow (which is essentially 

 fatty in its nature), or, at most, it is only the heads of the long bones that contain red marrow. 

 Where the blood-regeneration process is very active, however, the yellow marrow may be 

 changed into red, even throughout all the bones of the extremities {Neumann). 



8. DECAY OF THE RED BLOOD-CORPUSCLES. The blood corpuscles 

 undergo decay within a limited time, and the liver is regarded as one of the chief 

 places in which their disintegration occurs, because bile-pigments are formed from 

 haemoglobin, and the blood of the hepatic vein contains fewer red corpuscles than 

 the portal vein. 



The splenic pulp contains cells which indicate that coloured corpuscles are 

 broken up within it. These are the so-called " blood-corpuscle-containing cells " 

 (?j 102). Quincke's observations go to show that the red corpuscles which may 

 live from three to four weeks when about to disintegrate, are taken up by the white 

 blood-corpuscles in the hepatic capillaries, by the cells of the spleen and the bone- 

 marrow, and are stored up chiefly in the capillaries of the liver, in the spleen, 

 and in the marrow of bone. They are transformed, partly into coloured, and 

 partly into colourless proteids which contain iron, and are either deposited in a 

 granular form, or are dissolved. Part of the products of decomposition is used for 

 the formation of new blood-corpuscles in the marrow and in the spleen, and also 

 perhaps in the liver, while a portion of the iron is excreted by the liver in the bile. 



That the normal red blood-corpuscles and other particles suspended in the blood-stream are 

 not taken up in this way, may be due to their being smooth and polished. As the corpuscles 

 grow older and become more rigid, they, as it were, are caught by the amceboid cells. As cells 

 containing blood-corpuscles are very rarely found in the general circulation, one may assume 

 that the occurrence of these cells within the spleen, liver, and marrow of bone is favoured by 

 the slowness of the circulation in these organs {Quincke). 



Pathological. In certain pathological conditions, ferruginous substances derived from the 

 red blood-corpuscles are found in masses in the spleen, the marrow of bone, and the capillaries 

 of the liver: (1) When the disintegration of blood- corpuscles is increased, as in amemia 

 (Stahel). (2) When the formation of red blood-corpuscles from the old material is diminished. 

 If the excretion from the liver cells be prevented, iron accumulates within them ; it is also more 

 abundant in the blood-serum, and it ma)' even accumulate in the secretory cells of the cortex 

 of the kidney and pancreas, in gland cells, and in the tissue elements of other organs. When 

 the amount of blood in dogs is greatly increased, after four weeks an enormous number of 

 granules containing iron occur in the leucocytes of the liver capillaries, the cells of the spleen, 

 bone-marrow, lymph-glands, liver cells, and the epithelium of the cortex of the kidney. The 

 iron reaction in the last two situations occurs after the introduction of haemoglobin, or of salts 

 of iron into the blood {Ghicreck, v. Stark.) 



When we reflect how rapidly large quantities of blood are replaced after 

 haemorrhage and after menstruation, it is evident that there must be a brisk manu- 



