THE BLOOD 87 



Lesson II. Both serum globulin and serum albumin probably 

 consist of more than one proteid substance (see Lesson XX.). 



Fibrin ferment. — Schmidt's method of preparing it is to take serum 

 and add excess of alcohol. This precipitates all the proteids, fibrin 

 ferment included. After some weeks the alcohol is poured off; the 

 serum globuHn and serum albumin have been by this means rendered 

 insoluble in water ; an aqueous extract is, however, found to contain 

 fibrin ferment, which is not so easily coagulated by alcohol as the 

 other proteids are. A simpler method of preparing fibrin ferment 

 in an impure but eflBcient form is given in the footnote on p. 81. 



B. Extractives. — These are non-nitrogenous and nitrogenous. The 

 non-nitrogenous are sugar (0"12 per cent.), fats, soaps, cholesterin ; and 

 the nitrogenous are urea (0'02 to 0*04 per cent.), and still smaller 

 quantities of uric acid, creatine, creatinine, xanthine, and hj-poxanthine. 



C. Salts. — The most abundant salt is sodium chloride : it consti- 

 tutes between 60 and 90 per cent, of the total mineral matter. 

 Potassium chloride is present in much smaller amount. It consti- 

 tutes about 4 per cent, of the total ash. The other salts are phos- 

 phates and sulphates. 



Schmidt gives the following table : — 



1,000 paxts of plasma yield — 



Mineral matter 8'550 



Chlorine 3-640 



SO3 0115 



P.jOj 0-191 



Potassium . 0-323 



Sodium ........ 3-341 



Calcium phosphate 0-311 



Magnesiima phosphate ..... 0-222 



THE WHITE BLOOD CORPUSCLES 



These corpuscles are t}-pical animal ceUs. Their nucleus consists 

 of nuclein, their ceU-protoplasm yields proteids belonging to the 

 nucleo-proteid and globulin gi'oups. The nucleo-proteid obtained 

 from them is the zymogen of the fibrin ferment, the addition of a 

 calcium salt converting it into the ferment. The protoplasm of these 

 cells often contains small quantities of fat and glycogen. 



THE RED BLOOD CORPUSCLES 



The red blood corpuscles are much more numerous than the white, 

 averaging in man 5,000,000 per cubic miUimetre, or 400 to 500 red to 

 each white corpuscle. The method of enumeration of the corpuscles 

 is described in the Appendix. 



