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CHAPTER V. 

 THE HiEMORRHAGIC DIATHESIS. 



The physiology of the coagulation of the blood. Haemophilia. 

 Pathology of haemophilia. Treatment of haemophilia. The 

 therapeutics of calcium salts. 



WE are still far from a clear conception of the 

 exact pathology of haemophilia, purpura, and 

 the haemorrhagic tendency in jaundice, but it will 

 be only by a sound understanding of the normal 

 processes of coagulation of the blood that we shall 

 be able to comprehend the abnormal. 



The phenomena of blood-clotting are beautifully 

 designed to avoid two opposing evils ; if no provision 

 was made for fibrin formation every injury would be 

 fatal ; but on the other hand, if all the essentials for 

 the process were already present in the plasma, the 

 circulation would immediately be brought to a 

 standstill by intravascular thrombosis. Therefore 

 coagulation is made to be dependent on contact with 

 damaged cells, either tissue-cells or leucocytes, and 

 in particular with the nucleoprotein constituting 

 their nuclei, while the intact lining endothelium of 

 the blood-vessels has the power of preventing clotting. 

 We have all been told that a length of jugular vein 

 containing blood may be tied at each end and hung 

 up for a week, and no clotting occurs until damaged 

 tissue-cells are added. Thus we find that the very 



