233 



n i z a I i o n. In the ptM'niiilalion of Ihc vai-ious cjiKjlicnls of 

 the immunized and non-inmiunizeil strain and their re- 

 spective suljcultures under various conditions, we are aWe 

 to ohlain all possible kinds of information as to the con- 

 ditions of the strains during the process. We can. for in- 

 stance, get inforuialion as to the action of the small amount 

 of antigen on the innnunized strain during the process of 

 immunization. If the antigen in tliis low concentration should 

 have an}' growth-inhibiting effect, the quotient of the rates 

 of growth of the immunized strain and its control would 

 be below 1. Fig. 53 represents such a curve, showing the 



10 11 12 

 Passage 



13 14 15 16 17 18 19 20 21 22 



Fig. 53. 

 Curve stiowing the rate of growtli of the immunized strain and its control 

 through twenty-two passages Human ascitic fluid was used as antigen in 

 a concentration of 7 per cent. The ordinates represent the quotient of the 

 rate of growth of the immunized strain divided by that of its control, and 

 the abscissae the number of passages. 



effect of 7 per cent human ascitic fluid on a strain of fibro- 

 blasts during 22 passages. Fluctuations can be seen, the cause 

 is as yet unknown, but generally taken, the index is aboul 

 1 all the time, which denotes that the action of 7 per cent 

 human ascitic fluid has practically no inhibiting effect on 

 the strain. 



If the quotients of the rates of growth of both subcultures 

 of the immunized strain in low and high concentration are 

 figured out. and if the quotients of the rates of growth of 

 both subcultures of the non-immunized strain, without an- 



