240 



ANTITOXINS 



(d) Control Serum. As every normal seruin contains a certain 

 amount of antilysin, it is necessary to use a normal control serum. 

 Normal horse serum, dried in vacuo to prevent deterioration, and freshly 

 dissolved for each test in 10 volumes of sterile distilled water or salt 

 solution, has been advocated by Bruck, Michaelis, and Schulze. 



(e) The Test. It is first necessary to titrate the staphylococcus fil- 

 trate to ascertain the amount of lysin present. This is accomplished 

 according to the following scheme: 



TABLE 5. METHOD OF TITRATING STAPHYLOLYSIN 



In this test 0.1 c.c. is the smallest amount of lysin that can completely 

 hemolyze the given quantity of erythrocytes, and is taken as the unit 

 for the second part of the test. 



The lytic dose of filtrate just determined is now placed in a series of 

 small test-tubes, with increasing doses of serum to be tested and a con- 

 stant dose of corpuscles. 



TABLE 6. METHOD OF TITRATING ANTISTAPHYLOLYSIN IN A SERUM 



In this instance 0.05 c.c. of the patient's serum was sufficient com- 

 pletely to neutralize the lysin. 



A similar test is carried out with normal horse serum. The antilytic 

 dose of this serum is taken as 1, and the patient's serum is compared 



