154 THE FLUIDS. 



blood -serum even of pregnant women, and of the placental vessels. 

 The "seriim-caseine" may be merely albumen- deficient in alkali and 

 salts. (Lehmann.) 



The fats of the serum consist principally of stearic, oleic, and 

 margaric acids, and cholesterine. What has been called "seroline" 

 is a mixture of the crystallizable part of these fats. ; these prepon- 

 derating in the serum, while the more oily and yellow-colored are 

 found in the red corpuscles. Phosphoretted substances soluble in 

 ether do not exist in the serum, though they do in the corpuscles. 

 The amount of fat in the serum is not precisely determined, but it 

 is constantly increased during digestion. It is, on the average, 

 more abundant in the serum of women than in that of men. The 

 blood of the veins contains more fat than that of the arteries, and 

 the portal vein the most of all (p. 77). In diseases, the ordinary 

 fats appear to diminish, while the cholesterine increases. 



Glucose, or grape sugar (p. 70), is also a constituent of the blood- 

 serum, though in extremely small quantity. After the use of amy- 

 laceous or saccharine food it may be increased to 0.5 per cent. The 

 blood of the hepatic vein abounds in sugar, while that of the portal 

 vein contains only traces of it. Bernard has found that the glucose 

 is formed in the substance of the liver, and, sometimes at least, from 

 a nitrogenized material. M. Figuier's statement, that the sugar is 

 formed in "the portal vein and stored up in the liver, has not yet 

 been confirmed. 



Urea, hippuric acid, creatine, and creatinine exist in serum, but in 

 quantity too small to be determined. A peculiar yellow coloring 

 matter has also been supposed to exist in it, but this is not decided. 



Formic, acetic, and lactic acids may also exist in the serum, since 

 the first is formed in the perspiration, and the last in the muscles ; 

 but they have been detected only in the blood of the splenic vein. 

 Hypoxanthine has been found in the blood of the spleen. It occurs 

 also in case of leucasmia; as do the three acids just mentioned, and 

 glutin. 



Biliary coloring matter and acids occur only in diseased blood, and 

 sometimes when there is no decided lesion of the liver. Uric acid 

 has been found, with certainty, only in diseased blood, especially in 

 arthritis. 



Of the mineral constituents of the serum, the chloride of sodium 

 is the most abundant, averaging 61 per cent, of the ash. Next is 

 carbonate of soda, 28.9 per cent. Chloride of potassium varies 



