BACTERIOLOGY. 



195 



In pneumonic plague, the agglutination test has no clinical 

 value, for the patients succumb to the disease before antibodies 

 are produced or at least produced in any quantities that are 

 capable of detection. 



With regard to the second application of the method, as there 

 seemed to be some difference of opinion as to the value of the 

 agglutination test in identifying plague bacilli, we decided, after 

 our return to Manila, to carry out a series of experiments in the 

 hope of throwing further light upon this subject. The result 

 of our experiments in this direction will be described briefly. 



For obtaining an agglutinating serum, rabbits were used and 

 large doses of the bacilli were injected intravenously. Repeated 

 inoculation of living avirulent plague bacilli administered in this 

 way called forth a very satisfactory serum, but Jcilled virulent 

 bacilli failed to do so in every instance. All of the rabbits lost 

 weight rapidly during immunization. 



After obtaining a satisfactory serum, the various pneumonic 

 strains which we had brought back with us from Mukden, to- 

 gether with three bubonic strains and three strains from experi- 

 mental animals, were all subjected to the agglutination test with 

 the same plague serum. The organisms were grown at 32° C. 

 In order to avoid spontaneous sedimentation, the bacteria were 

 suspended in distilled water and the dilutions of the sera made 

 with 0.1 per cent sodium chloride solution. 



The greatest dilution of the immune serum, which caused 

 complete or almost complete agglutination, is recorded for each 

 strain tested in the following table: 



Table II. — Showing limit of agglutination in plague strains. 



Strain. 



Limit of 

 agglu- 

 tination. 



Strain. 



Limit of 

 agglu- 

 tination. 



Pneumonic plague: 

 No. 1 



160 

 160 

 640 

 320 

 160 

 160 

 640 

 160 

 640 

 320 

 160 

 820 

 640 

 640 

 640 



Pneumonic plague — Continued. 

 No. 22 



1.280 

 1,280 

 320 

 320 

 S20 

 320 

 320 

 320 

 640 

 320 

 (?) 



80 

 80 

 80 



No. 5 



No. 23 - 



No. 7 



No. 25 



No. 8 



No. 26 



No. 9 



No. 28 



No. 10 



No. 29 



Vo.Vi 



No. 32 



No. 13 





No. 14 





No. 15 - . . 





No. 16 



Arirulent plague . . 



No. 17 



Guinea pig: 



No. 5635 



No. 18 



No. 19 



No. 5769 



No. 21 



No. 5745 







