204 ORIENTAL PLAGUE chap. 



microbes, the vibrio of cholera and B. typhosus, as 

 regards the above reaction. The agglutinating action of 

 the blood serum of a cholera-prepared animal does not 

 ensue immediately, say within a'few days, but takes some 

 time, at least a fortnight, to develop ; whereas in the case 

 of a typhoid-prepared guinea-pig the agglutinating action 

 can be shown to have set in within a few days of the 

 injection, though of course it increases somewhat as time 

 passes. This fact was first noted in the case of typhoid 

 fever in man by Widal. He found that the blood serum 

 possesses early in the acute stage of the illness an aggluti- 

 nating action, and that the fact therefore is of great value 

 for diagnosis. As regards cholera in man, on the other 

 hand, it has been shown that the agglutinating action of 

 the blood cannot be demonstrated till about two or three 

 weeks after the disease has passed off. 



I now proceed to consider how and to what extent the 

 blood of animals previously " prepared " with plague 

 culture acquires agglutinating action. 



Experiments in Agglutination with Culture of 



B. PESTIS. 



Various observers — Paltauf ( Wiener Kl. Wochenschrift, 

 1897, N. 22) ; German Plague Commission (Arbeiten aus 

 dem Kaiserl, Gesundh. Band xvi. ) ; Russian Plague 

 Commission {Annates de VInstitut Pasteur, 1897, N. 7) ; 

 Vagedes (Arb. des K. Gesundh. Band xvii.) — have 

 described positive results on plague culture with the blood 

 of persons that have passed through and become con- 

 valescent for some weeks from an attack of bubonic plague. 

 Similar positive results have been noted with the blood of 



