yii INFECTION OF ANIMALS WITH PLAGUE 193 



November 7, i.e. after thirty days' drying, for injection of 

 guinea-pigs : — 



Guinea-pig No. 31. — " Sand-gelatine" plague. 



Guinea-pig No. 32. — " Earth-gelatine " plague. 



Guinea-pig No. 31 was found dead on November 16 

 with typical subacute plague. 



Guinea-pig No. 32 was found dead on November 14 

 with typical subacute plague. 



Experiment 17. — The materials were again used for 

 injection of guinea-pigs on November 22, i.e. after six 

 weeks and three days' drying : — 



Guinea-pig No. 33. — " Sand-gelatine " plague. 



Guinea-pig No. 34. — " Earth-gelatine " plague. 



Guinea-pig No. 34 was found dead on November 26 

 with typical subacute plague. 



Guinea-pig No. 33 remained unaffected. It was tested 

 after a fortnight by the subcutaneous injection with plague 

 culture and was found fully susceptible. 



Experiment 18. — The same "earth-gelatine" plague 

 was again used on November 29, i.e. after seven weeks and 

 three days' drying, one guinea-pig, No. 25, being injected 

 with it. The animal was found dead with typical sub- 

 acute plague. 



Experiment 19. — The last experiment with this same 

 material, viz. " earth - gelatine " plague, was made on 

 December 14, that is after nine weeks and four days' dry- 

 ing, one guinea-pig, No. 36, being injected subcutaneously 

 with turbid emulsion. The animal remained unaffected. 

 This animal a fortnight later was injected with B. pestis 

 of culture and promptly succumbed to plague. 



From this series it appears that the vitality of B. 



pestis in earth and in sand to which the micro-organism 



o 



