1174 PROTEIDS. 



their temperatures of heat coagulation in dilute saline solutions, e.g. 

 precipitability, etc. Cell-globulin-/? is stated to differ from true 

 paraglobulin, by possessing the power of hastening the clotting of 

 diluted salt-plasma, and the so-called ' fibrin-ferment ' is accordingly 

 regarded by some as identical with cell-globulin-/3 and arising from 

 the disintegration of leucocytes. 



The proteid constituent of the stroma of red blood-corpuscles 

 consists chiefly of a globulin usually regarded as identical with 

 paraglobulin, since its saline solutions coagulate at 75° and it is 

 precipitated from the same by saturation with sodium chloride and 

 a current of carbon dioxide. 



4. Fibrinogen. 



This globulin occurs in blood-plasma together with para- 

 globulin and serum-albumin. During blood-clotting it is 

 converted largely, if not entirely into fibrin. It is also found 

 in chyle, serous fluids and transudations, more particularly in 

 hydrocele fluids. 



In its general reactions it resembles paraglobulin but is 

 markedly distinguished from the latter by the following char- 

 acteristics. (1) As it occurs in plasma or in dilute solutions 

 of sodium chloride (1 — 5 p.c), it coagulates at 55 — 56°. 

 (2) It is very readily precipitated by the addition of sodium 

 chloride to its saline solutions until the whole contains 16 p.c. 

 NaCl, whereas paraglobulin is not appreciably precipitated until 

 at least 20 p.c. of the sodium salt has been added. 



Salted plasma, obtained by centrifugalizing blood whose 

 clotting is prevented by the addition of a certain proportion 

 of magnesium sulphate, is mixed with an equal volume of a 

 saturated (35-87 p.c. at 14° C.) solution of sodium chloride; 

 the fibrinogen is thus precipitated while the paraglobulin 

 remains in solution. The adhering plasma may be removed 

 by washing with a solution of sodium chloride, and the fibrin- 

 ogen finally purified by being several times dissolved in and 

 reprecipitated by sodium chloride. 



When a fluid containing purified fibrinogen is made to yield 

 fibrin by the action of fibrin-ferment, the amount of fibrin 

 formed is always less than that of the fibrinogen which disap- 

 pears at the same time. The deficit thus observed is at least 

 partly accounted for by the simultaneous appearance of a 

 globulin which coagulates, when heated in saline solution, 

 at 64°. 



5. Myosin. 



When an irritable contractile muscle passes into rigor, the 

 substance of which the muscle-fibres are chiefly composed 

 undergoes a change, analogous to the clotting of blood-plasma, 

 which results in the formation of a clot of myosin. By appro- 



