30 HISTORY OF THE CORPUSCLES. [BOOK i. 



been seen in circulating and even shed blood by various observers, 

 and it is this kind of corpuscle which Alex. Schmidt believes to 

 break up so largely and disappear, with the production of fibrin- 

 factors, when blood is shed. Making every allowance for contro- 

 verted points, we may conclude, that the red-medulla of bones has 

 an important function in giving rise to new red corpuscles, and 

 that after unusual loss or destruction of these bodies, the normal 

 activity of this tissue at least is greatly increased. 



When we come to treat of respiration, we shall bring forward 

 evidence that the red corpuscles, by virtue of haemoglobin, have a 

 most important use in carrying oxygen from the lungs to the 

 several tissues. It is through the red corpuscles that the tissues 

 themselves breathe, at least as far as breathing is the taking in of 

 oxygen. We do not know what wear and tear the red corpuscles 

 undergo in this respiratory function ; nor have we any evidence as 

 to any other work which they perform in the economy, and which 

 would tend to their being used up. But, as we have already urged, 

 we have reason to think that they afe~being constantly destroyed, 

 and apparently one place at least where this destruction goes on is 



rthe spleen. 



In this organ may be seen, as Kolliker long since pointed out, 

 large protoplasmic cells in which are included a number of red 

 corpuscles : and these red corpuscles may be observed in various 

 stages of apparent disintegration. Moreover the serum of the 

 blood of the splenic vein, unlike that of blood in general, is said to 



<be tinged with haemoglobin. It would seem therefore probable that 

 a certain amount ot haemoglobin is set free in the spleen from 

 disintegrating red corpuscles, and carried, in part at least, from 

 thence through the portal circulation to the liver. Whether any 

 large amount of destruction of red corpuscles goes on elsewhere we 

 do not know. 



Since the serum of blood, with the exception of that from the 

 splenic vein, contains no dissolved haemoglobin, it is clear that the 

 hemoglobin of the broken-up corpuscles must speedily be trans- 

 formed into some other body. Into what other body? In old 

 blood-clots (as in those of cerebral haemorrhage) there are fre- 

 quently found minute crystals of a body free from iron, which has 

 received the name hcematoidin. There can be no doubt that the 

 haematoidin of these clots is a derivative from the haemoglobin of 

 the escaped blood. We know 1 that haemoglobin contains, besides 

 a proteid residue, a residue not proteid in nature, called haematin. 

 We know further that haematin may lose the iron which it contains 

 (and which appears to be loosely attached), and yet remain a 

 coloured body. So that there is no difficulty in the passage from 

 the proteid-and-iron-containing haemoglobin to the proteid-and- 

 iron-free haematoidin. But haematoidin, not only in the form and 

 appearance of its crystals, but also, as far as can be ascertained by 

 1 See Chapter on Changes of Blood in Respiration. 



