ENDOCRINE FUNCTION OF THE THYMUS GLAND 



333 



3. Determination of the hemolysis inhibiting power of the normal 

 rat serum. To determine whether the substance or substances 

 in normal rat serum act as a kind of anti-amboceptor or anti- 

 complement, the following tests were made (table 10) : 



Showing the details in the determination of the inhibiting -power of normal rat serum 

 on the hemolysis of rat corpuscles by the immune antiserum 



After one hour at room temperature 



Guinea-pig serum 1: 10 (complement)... 

 2 per cent suspension of rat blood-cells, 



0.5 

 0.5 



0.5 

 0.5 



From table 10 we see that 0.5 cc. of ten times' dilution of the 

 normal rat serum can almost completely inhibit the hemolytic 

 action of just one unit of the hemolysin, when the guinea-pig 

 serum is used as complement. 



If.. Determination of a possible anticompleme?it substance. Using 

 normal guinea-pig serum (complement) instead of the one unit 

 of hemolysin before the incubation in the above test, and adding 

 just one unit of hemolysin and blood corpuscles afterward, we 

 got almost the same result as in the foregoing test. The limit 

 of the hemolysis inhibiting power of the normal rat serum against 

 the action of the antirat hemolysin is in both cases 0.4 to 0.5 cc. 

 of ten times the dilution of it. 



By using inactive rat serum, instead of active fresh serum, we 

 observed an equally negative hemolysis; that is, the hemolysis 

 inhibiting substance or substances seem to be heat stable. 



