COMPOSITION OF PLASMA AND SERUM. 49 



the finer vessels are frequently found plugged with small thrombi 

 (see Transfusion, p. 61). 



Coagulable Fluids. With regard to coagulability, fluids containing proteids 

 may be classified thus : 



(1.) Those that coagulate spontaneously, i.e., blood, lymph, chyle. 



(2.) Those capable of coagulating, e.g., fluids secreted pathologically in serous 

 cavities ; for example, hydrocele fluid, which, as usually containing fibrinogen only, 

 does not coagulate spontaneously, coagulates on the addition of fibrinoplastin and 

 ferment (or of blood-serum in which both occur). 



(3.) Those which do not coagulate, e.g., milk or seminal fluid, which do not seem 

 to contain fibrinogen. 



32. Chemical Composition of the Plasma and 



Serum. 



I. Proteids occur to the amount of 8 to 1 per cent, in the plasma. 

 Only 0*2 per cent, of these go to form fibrin. When coagulation has 

 taken place, and after the separation of the fibrin, the plasma becomes 

 converted into serum. The S. G. of human serum is 1,027 to 1,029. It 

 contains several proteids. [According to Hammarsten, human serum 

 contains 9*2075 per cent, of solids, of these, 3*103 = serum-globulin, 

 and 4*516 = serum-albumin, i.e., in the ratio of 1 : 1*511.] 



(a.) Serum-Globulin (Th. Weyl) or Para-Globulin 2 - 4 p. c., was 

 formerly believed to occur in much smaller amount than it actually 

 does. Hammarsten found that if serum be diluted with two volumes 

 of water, and crystals of magnesium sulphate be added to saturation, 

 serum-globulin is precipitated, but not serum-albumin. In the serum 

 of the horse and ox serum-globulin is more abundant than serum- 

 albumin, while in the serum of the rabbit and dog the reverse is 

 the case. It is soluble in 10 per cent, solution of common salt, and 

 coagulates at 75C. 



[Serum-globulin was carefully described by Panum under the name of "Serum- 

 casein;" by Al. Schmidt, as " Fibrino-plastic substance;" and by Ktthne, as 

 "Para-globulin."] 



As already mentioned, it may also be precipitated, in part, by diluting serum 

 with 10 to 15 vols. of water, and passing a stream of C02 through it (p. 44). If a 

 trace of acetic acid be added to serum after the separation of the serum-globulin, 

 Kuhne finds that a fine precipitate of what he calls soda-albuminate occurs. [It 

 is, however, highly doubtful if an alkali-albuminate does occur in the blood. 

 Hammarsten found that C0 2 does not precipitate all the serum-globulin, so that 

 it is improbable that Kiihne's soda-albuminate exists as a distinct substance 

 in serum.] 



According to A. E. Burckhard, magnesium sulphate not only precipitates 

 serum -globulin, but also another proteid substance more closely resembling 

 albumin. During hunger the globulin increases and the albumin diminishes. 



(5.) Serum- Albumin. Its solutions begin to be turbid at 60C., 

 and coagulation occurs at 73C., the fluid becoming slightly more 



4 



