72 STUDIES IN ADVANCED PHYSIOLOGY. 



be confused with the serum itself. Serum is the name 

 applied to the entire liquid after the fibrinogen has been 

 removed in the form of fibrin, while serum albumen is but 

 one of the albumens found in this liquid. Fibrinoplastin, so 

 called by Al. Schmidt, and called paraglobulin by Kiihne, 

 is present to the amount of about one per cent. The serum 

 albumen forms four or five per cent. These two albumens 

 are insoluble in pure water, but are soluble in water con- 

 taining a little common salt, which latter accounts for their 

 being in solution in normal blood. The two differ but very 

 little from each other, but they may be separated if to a 

 solution of serum at a temperature of about ninety-five 

 degrees Fahrenheit, crystals of magnesium sulphate be 

 added to saturation. The fibrinoplastin is by this process 

 precipitated out of the solution. 



As stated before, the serum albumen is the main nutri- 

 tive factor of the blood. It is almost identical with liquid 

 egg albumen, and differs from it only in its reaction with 

 certain chemical agents. It is this albumen which in 

 pathological conditions of the kidneys, such as Bright 's 

 disease, is eliminated in the excretion. Both serum albu- 

 men and fibrinoplastin may be made to coagulate if blood 

 serum be heated to a temperature of about one hundred 

 and seventy-six degrees Fahrenheit. 



The serum further contains traces of fat in the form of 

 fine granules, to the amount of about one-half per cent. 

 After a diet rich in fats the amount may reach one per 

 cent. Traces of grape sugar in amounts varying from one- 

 tenth to three-tenths of a per cent, occur. This amount 

 may also greatly vary with a diet rich in sugars. It further 

 contains in very small amounts a number of organic nitrog- 

 enous compounds, such as kreatin, urea, and uric acid, 

 substances with which we shall be further concerned in the 

 discussion of assimilation and nutrition. The mineral salts 

 are represented in an amount reaching not quite one per 

 cent. Of these common salt, or sodium chloride, forms 

 more than half, and sodium carbonate a good portion of the 



