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STRONG. 



DURATION OF IMMUNITY AFTER VACCINATION. 



Series 55. — Demonstrating duration of immunity in monkeys after vaccination. 



The animals comprising this series were vaccinated with the strains "Pest 

 Avirulent" and "Maassen Alt" at different times, as may be seen from the table 

 below. From nine to ten months after the vaccination they were all collected 

 and on November 12 reinfected by the inoculation of f oese of the strain "Pest 

 Virulent" (from guinea pig 2764, second transplant). 



Animal 

 No. 



Vaccina- 

 ted. 



Reinoculated 

 November 12. 



Result. 



Autopsy and remarks. 



2842 



Jan. 



10 



§ oese "Pest 

 Virulent." 



Dead Nov. 19. after 7 days— 



Pest bubo containing few or- 

 ganisms. No bacilli in smears 

 from spleen. 



2843 



Jan. 



1? 



do 



Alive and well 





2844 



Jan. 



15 



- -do 



Dead Nov. 16, after 4 days— 



Numerous pest bacilli in smears 

 from spleen. 



2845 

 2846 



Jan. 

 Jan. 



16 

 18 



do 



do 



Alive and well 



Few swollen pest bacilli in 



Dead Nov. 20, after 8 days— 













smears from spleen. 



2847 



Jan. 



22 



... do .. . 



Dead Dec. 1, after 19 days __ 



Chronic bubo containing few 

 pest bacilli. 



2848 



Jan. 



25 



do 



Dead Nov. 17, after 5 days__ 



Numerous pest bacilli in smears 

 from spleen. 



2849 

 2850 



Jan. 

 Jan. 



27 

 29 



do 



do 



Alive and well - 





- do __ „ 







