

THE CORPUSCLES OF THE BLOOD. 43 



corpuscles, to keep up the normal supply of haemoglobin ; and, indeed, the 

 cases in which after even great loss of blood by hemorrhage a healthy 

 ruddiness returns, and that often rapidly, showing that the lost corpuscles 

 have been replaced, as well as the cases of recovery from the disease anaemia, 

 prove that red corpuscles are, even in adult life, born somewhere in the 

 body. 



In the adult, as in the embryo, the red corpuscles appear to be formed 

 out of preceding colored nucleated cells. 



In the interior of bones is a peculiar tissue called marrow, which, in most 

 parts being very full of bloodvessels, is called red marrow. In this red 

 marrow the capillaries and minute veins form an intricate labyrinth of rel- 

 atively wide passages with very thin walls, and through this labyrinth the 

 flow of blood is comparatively slow. In the passages of this labyrinth are 

 found colored nucleated cells, that is to say, cells the cell substance of which 

 has undergone more or less differentiation into haemoglobin and stroma. 

 And there seems to be going on in red marrow a multiplication of such 

 colored nucleated cells, which become transformed into red non-nucleated 

 discs, that is, into ordinary red corpuscles, and pass into the general blood 

 current. In other words, a formation of red corpuscles, not wholly unlike 

 that which takes place in the embryo, is in the adult continually going on 

 in the red marrow of the bones. 



A similar formation of red corpuscles has also been described, though 

 with less evidence, as taking place in the spleen, especially under particular 

 circumstances, such as after great loss of blood. 



The formation of red corpuscles is, therefore, a special process, taking 

 place in special regions ; we have no satisfactory evidence that the ordinary 

 white corpuscles of the blood are, as they travel in the current of the circu- 

 lation, transformed into red corpuscles. 



The red corpuscles, then, to sum up, are useful to the body on account of 

 the haemoglobin, which constitutes so nearly the whole of their solid matter. 

 What functions the stroma may have besides the mere, so to speak, mechan- 

 ical one of holding the haemoglobin in the form of a corpuscle we do not 

 know. The primary use of the haemoglobin is to carry oxygen from the 

 lungs to the tissues, and it would appear that it is advantageous to the econ- 

 omy that the haemoglobin should be as it were bottled up in corpuscles rather 

 than simply diffused through the plasma. How long a corpuscle may live 

 carrying oxygen we do not exactly know ; the red corpuscles of one animal, 

 e. g., a bird, injected into the vessels of another, e. g., a mammal, disappear 

 within a few days ; but this affords no measure of the life of a corpuscle in 

 its own home. Eventually, however, the red corpuscle dies, its place being 

 supplied by a new one. The haemoglobin set free from the dead corpuscles 

 appears to have a secondary use in forming the pigment of the bile and 

 possibly other pigments. 



The White or Colorless Corpuscles. 



28. The white corpuscles are far less numerous than the red ; a speci- 

 men of ordinary healthy blood will contain several hundred red corpuscles 

 to each white corpuscle, though the proportion, even in health, varies consid- 

 erably under different circumstances, ranging from 1 in 300 to 1 in 700. 

 But though less numerous, the white corpuscles are probably of greater 

 importance to the blood itself than are the red corpuscles ; the latter are 

 chiefly limited to the special work of carrying oxygen from the lungs to the 

 tissues, while the former probably exert a considerable influence on the blood 

 plasma itself, and help to maintain it in a proper condition. 



