220 THE INCOME OF ENERGY 



inject the immunized mice with a dose one 

 hundred times as great. 1 



Observe the non-immune and the immune mice 

 for several days and note the results. 



Ehrlich continued the above experiment until the 

 immunized mouse received daily 0.5 gm. of the ricin 

 by the mouth. Such animals bore safely subcutaneous 

 injections of 3^ and even more.. The immunity also 

 appeared in that solutions of 0.5-1.0 per cent applied 

 to the eyes of non-immune mice caused violent pauo- 

 phthalmitis, while immune mice bore easily the appli- 

 cation of 10 per cent solutions. 



This absolute local immunity was fully established 

 when the general immunity had attained only a 

 middle grade. Normally the subcutaneous injection 

 of ^sViJTF ricin solution causes severe local inflamma- 

 tion, but thoroughly immunized animals bear T ^ v . 

 Quantitative experiments show that the resistance to 

 the poison is not increased during the first four days, 

 and the increase is doubtful on the fifth day, but on 

 the sixth day a relatively high (for example thirteen- 

 fold) general immunity is suddenly established. The 

 sudden fall toward normal temperature observed in 

 diseases with a " crisis," such as pneumonia, may de- 

 pend on the " critical " establishment of immunity. 



Immunity is not increased by continued administra- 

 tion of the same dose, day by day. An equilibrium 

 appears to be established. 



1 The mice in these experiments must be carefully protected 

 against cold and wetting. 



