248 



BARBER. 

 Table I. 



Num- 

 ber of 

 guinea 

 pigs 

 inocu- 

 lated. 



Previous treatment. 



Died 



of 



plague. 



Recov- 

 ered. 



Average 

 number 



of days of 

 survival 



after inoc- 

 ulation 

 in fatal 

 cases. 



Remarks. 



1 



2 



16 

 2 



2 



4 



2 



1 



1 



9 



5 



Recovered from infection with 

 virulent plague. 



Recovered from infection with 

 plague strain "Shanghai." 



No previous immunization 



Avirulent pest alone, (about i^ 

 slope). 



About 55 loop of avirulent pest 

 in 5 and i cc. agar. 



About TiTosT) loop in 1 cc. ordi- 

 nary agar. 



About TtiJirs loop in 1 cc. 4 per 

 cent agar. 



About loffiHS loop in 2 cc. 4 per 

 cent agar. 



About TToOT loop in 3 cc. 4 per 

 cent agar. 



About inJiiir loop in 3 cc. 4 per 

 cent agar. 



About nresn loop in 1 cc. ordi- 

 nary agar. 











16 

 2 



2 



3 



1 

 1 

 1 

 6 

 2 



1 



2 





 







1 



1 





 

 3 

 3 





Marked infiltration at point 



of inoculation. 

 Marked infiltration at point 



of inoculation. 



Immunizing doses given 

 from 30 to 60 days before 

 test dose. 



All agar and pest given 

 subcutaneously except in 

 last-mentioned group of 

 5 where inoculation was 

 intraperitoneal. 





4.8 

 11.0 



6.5 



5.3 



3 



« 

 3 



8.8 



5 



In the series representeci by Table I, all nonimmunized con- 

 trols dieci of plague within six days after inoculation, except one 

 which survived nine days. The 16 in this group include 6 which 

 were inoculated without infection some two to three months 

 previously with single small doses of 2 to 100 plague bacilli, 

 either virulent or of the "Shanghai" strain — a somewhat atten- 

 uated race. There was apparently no immunizing effect of these 

 single small doses. Of the immunized group, the two which 

 received avirulent pest bacilli alone in a considerable dose (about 

 1 cubic centimeter of a thin suspension) died in thirteen and nine 

 days after the test dose. Of the 24 which had received avirulent 

 pest in agar, 8 recovered from the test dose. 



In Table II are given the results for a second group of guinea 

 pigs. Here all animals received in immunization a much larger 

 amount of avirulent plague in a larger amount of agar and the 

 doses were given intraperitoneally. The test dose was in all 

 cases given thirty-seven days after the avirulent pest agar. This 

 test dose consisted of about 500,000 bacteria of the same 

 highly virulent strain as that used in the first group, and was 



