RESEARCHES ON CERTAIN PROBLEMS OF PLAGUE IMMUNITY 25 



Reference has been made to the serum of the Horse " Pr." The 

 results of a number of tests relating to the serum of this horse are shown 

 in the accompanying Tables :— XV., XVI., XVII. and XVIII. 



TABLE XV. 

 TESTING SERUM OF "Pr." (6. IV). 



Mice of 15-20 grammes weight. 



Toxin (Subcutaneously at least = 4 lethal doses; intraperitoneally 

 lethal doses). 



Serum and Toxin mixed and placed i hour in the incubator at 37° C. 



Mixture injected subcutaneously. 



= 10 



Mixture injected intraperitoneally. 



5. -2 M -I n 



6. *2 II 'I n 



7. '2 II '2 II 



8. '2 II '2 II 



Controls : — Same quantities of Toxin ; serum of normal Horse " F." 

 Subcutaneous. 



Lived. 



Lived. 



Died in 48 hours. 



Lived. 



(135) 



