76 THE PRESERVATION OF SERUMS METHODS 



In this manner the risk of contaminating a stock bottle is obviated. 

 In the preservation of normal serum or the serum of luetics to be used 

 as controls for the Wassermann reaction, it is better to store them in 

 small amounts in sterile ampules. 



As a rule, it is best not to add a preservative to serums that are to be 

 used for purposes of immunization, for if the dose of serum is large, 

 enough preservative may be injected to place the health of the animal 

 in jeopardy. However, chloroform may be added in proportion of 1:10 

 or 1 : 20, provided the serum is placed in the incubator or heated in the 

 water-bath at 40 C. for fifteen minutes in order to drive off the chlo- 

 roform previous to injection. 



PRESERVATION OF IMMUNE SERUMS 



Immune serums may be preserved either in the fluid or in the dry 

 form. 



Preservation in Fluid Form with Antiseptics. Practically any 

 immune serum may be preserved in the fluid state by adding a suit- 

 able preservative in the proper dose without exerting any deleterious 

 influence on the antibody content. The exceptions to this general rule 

 are the precipitin-serums, because these should be crystal clear, and 

 a preservative may render the serum slightly cloudy. According to 

 Uhlenhuth, Weidanz, and Wedemann, such serums should be filtered 

 through a 'sterile Berkefeld filter and then stored without adding an 

 antiseptic. 



Various antiseptics have been advocated for the preservation of 

 serums. Hemolytic serum is well preserved by adding an equal amount 

 of chemically pure glycerin to the serum after it has been inactivated by 

 heating at 55 C. for a half-hour in a water-bath. The addition of 0.1 

 c.c. of a 1 per cent, solution of phenol in salt solution to each cubic 

 centimeter of immune serum usually suffices to keep the fluid free from 

 contamination, and produces only very slight, if any, clouding. Like- 

 wise, the addition of 2 per cent, formalin in a 5 per cent, solution of 

 glycerin in normal salt solution, in the proportion of 1 : 10, makes a very 

 useful antiseptic. Neither lysol nor trikresol should be used in the 

 preservation of a serum, as they are more likely to produce clouding 

 than does phenol. 



Preservation in Fluid Form, by Bacteria-free Filtration. If serums 

 are to be preserved in fluid form without the addition of an antiseptic, 

 special precautions in bleeding, collecting, and separating should be 



