in 



THE PROTEINS OF PLASMA 



109 



result is readily attained by adding to the plasma an 

 equal volume of a saturated solution of sodium chloride 

 which contains about 30 per cent, of salt. The fibrinogen 

 separates out from solution as a fine, flocculent, viscid 

 precipitate. Fibrinogen is characterised by the fact 

 that it "sets" or coagulates when heated in solu- 

 tion to 56' C. (132' F.). The second is called para- 

 globulin and is similarly precipitated when the 



Fig. 35. — Network of FiLAsrENTS left after washing away the 

 Colouring Matter from a thin, flat Clot of Blood. (Ranvier.) 



plasma from whicli the fibrinogen has been removed is 

 subsequently saturated by the addition of as much sodium 

 chloride as it will dissolve. It coagulates when heated in 

 solution, at a temperature much higher than does 

 filniiiugen, namely 75=^ C. (167" F.). The third is known 

 as serum-albumin. It may, roughly speaking, be 

 regarded as very like that kind of albumin with which 

 every one is familiar in the white of an egg, and while it 



