Il6 LECTURES ON IMMUNITY 



probably differs little from that given above. They are 

 for the typhoid-agglutinin, /^ 40 = 33,000, /-t 120 = 18,700, and 

 ^ 180 =8soo (the indices represent the time in minutes). 

 For the coli-agglutinin there are two different series. The 

 one proceeds regularly, so that p sinks with increasing time. 

 In the other series an irregularity occurs ; the /rvalue at 

 first sinks, then passes through a minimum and thereafter 

 through a maximum, and then later on falls toward zero 

 with increasing time. The two series were carried out 

 with the same preparations, so that the differences may 

 be regarded as purely accidental. But the limit-value /^ 

 seems to be nearly the same in the two series. 



The phenomenon of agglutination bears a great simi- 

 larity to that of haemolysis in its dependence on time and 

 temperature. We know from Eisenberg and Volk's ex- 

 periments that the absorption of the agglutinins reaches 

 the state of equilibrium in a few minutes (less than 5). 

 But still the agglutination continues through hours, espe- 

 cially at low temperatures. The phenomenon proceeds 

 with time just as does haemolysis, although the haemolytic 

 substance is absorbed before the time of the first observa- 

 tion. The following figures, giving the quantity of coli- 

 agglutinin necessary to reach the observed degree of 

 agglutination at 36.6 and 12.3 C, may illustrate this 

 peculiarity : 



Time (min.) 20 30 50 65 80 120 

 (? obs. at 36.6 4 i 0.5 0.2 0.13 o.i 

 (? obs. at 12.3 85 26 10 2 1.6 0.32 



The figures indicate that the limit-value for infinite time 

 is nearly reached in 120 minutes at the higher temperature, 

 but not for the lower one; and that this limit-value is of 



