CONCENTRATION OF ANTIBODIES 



This experiment is one of four performed on normal animals, and 

 gives a fair idea of the concentration of the agglutinins in the body 

 fluids. There are, of course, variations between animals even in 

 the same species. In all of our experiments the concentration of 

 agglutinins was highest in the serum, less in the thoracic and the 

 neck lymph, and the pericardial fluid contained agglutinins in only 

 one case. The cerebrospinal fluid and the aqueous humor did not 

 contain any in any case. 



B. Actively immunized animals. We made a study of the fluids 

 of five immunized cats. Three had received repeated subcutaneous 

 injections of typhoid bacilli. For the first few injections killed cul- 

 tures, but later live cultures were used. The doses injected were 

 increased gradually and careful record of the weight and general 

 condition kept, to guard against pushing the process too rapidly. 

 The remaining two animals received a single large injection of six 

 living 24-hour cultures. The results given in Table 7 may be taken 

 as fairly typical. 



TABLE 7. 

 THE COMPARATIVE AGGLUTINATING POWER ON THE TYPHOID BACILLUS OF THE BODY FLUIDS OF AN 



IMMUNIZED CAT. 



(Immunized by repeated subcutaneous injections. Fluids collected five 

 days after the last injection.) 



Control=o. 



The other experiments showed some variations. In two cases in 

 five the agglutinins were as concentrated in the thoracic lymph as in 

 the serum, in the remaining three of five the serum was by far the 

 more concentrated of the two. In one case the neck lymph showed 

 the same concentration of agglutinins as the thoracic lymph, but both 

 were considerably lower than the serum; in the four remaining cases 

 the concentration in the neck lymph was lower than in the thoracic 

 lymph. Agglutinins were found in four of five cases in the peri- 

 cardial fluid, but in no case in a dilution higher than i : 10. Agglu- 

 tination in the fifth case was questioned. The cerebrospinal fluid 



