THE BACILLUS OF PLAGUE. 117 



Calmette and Borrel (33), Galeotti and Malenchini (34), 

 Wladimiroff (35) and others, and the members of the 

 several Plague Commissions in Bombay have furnished long 

 reports on the value of the serum treatment in plague as a 

 preventive and therapeutic measure. In Haffkine's method, 

 which is similar in principle to that practised by him as a 

 protection against cholera and typhoid, a fluid preparation 

 obtained from dead cultures of pest-bacilli is employed ; 2.5 

 c.c. is injected into the forearm of an adult ; fever of slight 

 amount accompanied by pain and swelling at the seat of 

 injection are the chief phenomena of the reaction. This 

 treatment affords considerable but not absolute protection, 

 and its beneficial effect tends to disappear. Yersin, Calmette 

 and Borrel consider filtrates of cultures which contain toxin 

 are useless for protective purposes. By employing the 

 serum of horses that have been immunised by subcutaneous 

 injection of cultures of the pest-bacillus warmed to 58° C, 

 mice and other animals can both be protected from and 

 cured of plague. That serum so prepared has specific anti- 

 toxic power appears to be proved, since the serum of normal 

 horses, the anti-diphtheritic serum of Roux, the antitetanic 

 serum of Roux and Vaillard, the antivenin of Calmette and 

 the antistreptococcic serum of Marmorek, were all found to 

 be useless as a means of protection against an infection by 

 virulent plague-bacilli. An analysis of cases treated by 

 Yersin's serum shows that while the mortality in hospitals 

 is 80 per cent, of those attacked, this number is reduced to 

 49 per cent. By experiments made on monkeys (Semno- 

 pithecus entellus the grey, and Macacus radiatus the brown 

 ape, the latter of which is remarkably susceptible to plague) 

 Galeotti and Malenchini have established the therapeutic 

 and protective value of the serum of horses that have been 

 rendered immune by the repeated injection of small amounts 

 of toxin. 



With the development of bacteriology not only have the 

 specific forms that determine disease been isolated, but the 

 progress of this science has shown all civilised countries the 

 way to guard against the introduction of such a scourge as 

 plague, which in former centuries half depopulated the large 



