COLLOIDS OF PLASMA SO.'i 



solutions. They therefore require to have a certain concentration 

 of electrolytes present if they are to remain in solution. They 

 may l)c partially separated from albumin by dialysis. When the 

 salt content of plasma is forced below a concentration of about 

 0-2 per cent., the globulins are almost completely precipitated. 

 In the blood -stream they function to a great extent as regulators 

 of the amount of NaCl present. It is of importance that this fact 

 be thoroughly grasped. Where the amount of globulin in the 

 blood is increased, the chloride content increases, e.g. in pneumonia. 

 In patients with this infection, as well as in cases of chronic 

 nephritis and syphilis, the total protein content of plasma is 

 decreased and the globulin content increased both absolutely and 

 relatively. In mild infections and in chronic septic conditions 

 the total amount of protein present remains normal, while the 

 amount of globulin and of chlorides shows a marked increase. 

 NaCl held by globulin acts as if adsorbed, i.e. exerts no osmotic 

 pressure. Cilobulin is precipitated by an increase in hydrogen 

 ions. It is specially sensitive to COg. 



(y) Fibrinogen, a globulin formed in the reticulo-endothelial 

 cells of the liver (Faludi). 



The osmotic pressure in the vessels is due to proteins. They 

 are also responsible for the viscosity of blood. The removal of 

 the proteins from blood lowers its viscosity to very little greater 

 than that of water. After extensive bleeding water pours into 

 the vessels from the tissues through the lymph, and the specific 

 gravity, viscosity, etc., drop. The blood ceases to be an efficient 

 carrier. Bayliss found that the injection of a non-toxic emulsoid 

 colloid would restore normal conditions for sufficiently long a time 

 as would enable the cell-factories, especially the liver, to manu- 

 facture new blood proteins from the amino acids in the blood. 

 The most efficient sol, he found, was a solution of gum arable in 

 Ringer's solution. The story of this discovery as told in his 

 monograph is one of the most interesting side-lights on the medico- 

 scientific work of the war. 



Clotting 



The main use of fibrinogen lies, not in its viscosity or in its 

 osmotic pressure, but in its property of changing from a sol into 

 a gel. The clotting of plasma prevents the loss of blood and keeps 

 the blood channel free from any angularities. The evolution of 

 the knowledge of the process of clot formation has been very 

 slow, and even now the physico-chemical reactions involved are 

 anything but well understood. 



