W(CJ 



o 



(0 



234 



ligon, and in ;i liiuli coiiccnlrnlion oT iinlit^cn ;irc lij^urcd 

 oul, il can he seen llial llic ininnniizcd sli'ain i^rows 

 more rapidly llian llic non-innnuni/.cd. I'i;^. .")!. and lii;. 5.") 

 illuslrali lliis. I'hcsc ai'c examples ol' llic mode ol' inlcr- 

 pi-(iin,n llic cx|)crimcnls. 



In order lo dcmonslralc in a clear way llic various 

 (jnolicnls ol' rates ol' j^rowlli which I liaxc menlioned 

 here, il is simpler to look al Ihe Tollowinj^' di^raiii. ri,,i>. ,")(>. 

 l-'roin Iliis it can he seen llial A is a cnllurc willi a small 

 amounl ol' anli<*en. A, and A. show llic same culture divide<l 

 in halves. Aj is carried on in a medimn containing a small 



12 3 4 5 6 7 



9 10 11 12 13 14 15 16 17 18 19 20 

 Passaige 



Fig. 54. 

 Curve 1 shows the variations in the quotient of the rate of growth of the 

 immunized strain in a small amount of antigen divided by the rate of growth 

 of the same strain in a high concentration of antigen. Curve 2 shows the 

 variations in the quotient of the rate of growth of the non-immunized strain 

 in the ordinary medium divided by the rate of growth of the same strain 

 in a high concentration of antigen. Human ascitic fluid was used as antigen 

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

 the rates of growth, and the abscissae the number of passages. 



amounl of antigen (the conlinualion ol Ihe experiment);. 

 A2 (subculture) is transferred to a medium containing the 

 antigen in a toxic concentration. B is the control cullurc. 

 Bi is canicd on as B, the control culture (conlinualion of 

 the control), and B, is IransTcrrcd to a medium containing 

 the antigen in a toxic concentration. 



A, 

 Ilei'eof follows that ^ ex|)resses Ihe degree of immuni- 

 zation of A. 



