SERALBUMINS. 261 



and carbohydrate acids of unknown kinds. It has not been shown 

 whether these small amounts of carbohydrate are derived from the globulin 

 or from other contaminating bodies. According to ZANETTI and also 

 BYWATERS, the blood-serum contains a glucoproteid, seromucoid, and 

 the investigations of EICHHOLZ l seem to show that the globulins are 

 contaminated by a glucoproteid. According to LANGSTEIN the sugar 

 is not only mixed with the globulin, but it exists in a combined form, 

 probably in loose combination. 



Serglobulin (the euglobulin) may be easily separated as a fine floc- 

 culent precipitate from blood-serum by neutralizing or making faintly 

 acid with acetic acid and then diluting with 10-20 vols of water. For 

 further purification this precipitate is dissolved in dilute common salt 

 solution, or in water with the aid of the smallest possible amount of 

 alkali, and then reprecipitated by diluting with water or by the addition 

 of a little acetic acid. All the serglobulin may also be separated from 

 the serum by means of magnesium or ammonium sulphate; in these 

 cases it is difficult to completely remove the salt by dialysis. As long 

 as we are not agreed as to the number of globulins in the serum, it is 

 not necessary to give a method of separating the various globulins in this 

 mixture. Thus far the fractional precipitation with (NH^SO* has 

 chiefly been used. The serglobulin from blood-serum is always contam- 

 inated with lecithin and thrombin. A serglobulin free from thrombin 

 may be prepared from ferment-free transudates, as sometimes from 

 hydrocele fluids, and this shows that serglobulin and thrombin are dif- 

 ferent bodies. For the detection and the quantitative estimation of 

 serglobulin we may use the precipitation by magnesium sulphate added 

 to saturation (HAMMARSTEN) , or by an equal volume of a saturated 

 neutral ammonium-sulphate solution (HOFMEISTER and KAUDER and 

 POHL 2 ) . In the quantitative estimation the precipitate is collected on a 

 weighed filter, washed with the salt solution employed, dried with the 

 filter at about 115 C., then washed with boiling-hot water, so as to 

 completely remove the salt, extracted with alcohol and ether, dried, 

 weighed, and incinerated to determine the ash. This method, according 

 to the investigations of WIENER, S can only be used when the serum is 

 sufficiently diluted with water. 



Seralbumins are found in large quantities in blood-serum, blood- 

 plasma, lymph, transudates, and exudates. Probably they also occur 

 in other animal fluids and tissues. The proteins which pass into the 

 urine under pathological conditions consist largely of seralbumin. 



The seralbumin, like the serglobulin, seems also to be a mixture of 

 at least two protein bodies. The preparation of crystalline seralbumin 



1 Zanetti, Chem. Centralbl., 1898, I, p. 624; Bywaters, Journ. of Physiol., 35, and 

 Biochem. Zeitschr., 15; Eichholz, Journ. of Physiol., 23. 



2 Hammarsten, 1. c.; Hofmeister, Kauder and Pohl, Arch. f. exp. Path. u. Pharm., 20. 



3 Zeitschr. f. physiol. Chem., 74. 



