CHAPTER V 



THE BLOOD : PLASMA 



CONTENTS. 1. Different methods for separation of blood plasma from 

 corpuscles. '2. Histogenic substances or proteins of plasma : tibrinogen, serum 

 globulin, serum albumin, sero-mucoid. 3. Nitrogenous histolytic products of 

 plasma. 4. Fatty substances. Carbohydrates and their derivatives. 5. Inorganic 

 substances. Blood gases. 6. Theory of Coagulation : (a) conditions of blood 

 coagulation ; (b) disintegration of corpuscles as cause of coagulation ; (c) 

 fibrinogen as fibrin generator ; (d) analogies between blood coagulation and 

 curdling of milk ; (c) importance of time in coagulation ; (/) thrombin and 

 uucleins as coagulating substances ; (</) histone and cytoglobulin as anti- 

 coagtilating substances. 7. Osmotic pressure, molecular concentration, electrical 

 conductivity and viscosity of blood and serum. 8. Functions of the blood : (a) 

 effects of bleeding ; (b) effects of transfusion of homo- and heterogeneous blood ; 

 (c') bactericidal and immunising properties of blood and serum. Bibliography. 



I. THE property by which the blood coagulates spontaneously a 

 few moments after it has been drawn from the veins, and the 

 instability of the corpuscles, which renders them liable to injury 

 from the slightest causes, owing to modification of their osmotic 

 and secretory properties, make it difficult and almost impossible 

 to separate the plasma from the total mass of corpuscles, or formed 

 elements, in the identical amount and composition in which it 

 circulates in the vessels. 



To effect this as perfectly as possible, horse's blood must be 

 employed, since this, as has been said, coagulates slowly, and gives 

 time for the red corpuscles (which have a higher specific gravity) 

 to separate partially from the plasma and sink towards the 

 bottom of the vessel. If the blood streaming from the veins is 

 cooled to about C. by receiving it in a tall narrow cylindrical 

 vessel, surrounded with ice, coagulation can be retarded so long- 

 that after about an hour the transparent plasma, free from 

 erythrocytes, and containing only a small admixture of leucocytes, 

 floats 011 the corpuscles, and can be removed with a previously 

 cooled pipette (Briicke). It is, however, impossible by this 

 method, even with all the precautions suggested by experience, 

 to avoid a certain diffusion of haemoglobin from the corpuscles to 

 the plasma, which then becomes more or less tinted and shows 

 the characteristic spectrum of oxyhaemoglobin. 



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