436 PLAGUE 



1. Preventive Inoculation Hqfkine's Method. To prepare 

 the preventive fluid, cultures are made in flasks of bouillon with 

 drops of oil on the surface (in India Haffkine employed a 

 medium prepared by digesting goats' flesh with hydrochloric 

 acid at 140 C. and afterwards neutralising with caustic soda). 

 In such cultures stalactite growths (vide supra) form, and the 

 flasks are shaken every few days so as to break up the stalactites 

 and induce fresh crops. The flasks are kept at a temperature 

 of about 25 C., and growth is allowed to proceed for about 

 six weeks. At the end of this time sterilisation is effected by 

 exposing the contents of the flasks to 65 C. for an hour; 

 thereafter carbolic acid is added in the proportion of *5 per cent. 

 The contents are well shaken to diffuse thoroughly the sediment 

 in the fluid, and are then distributed in small sterilised bottles for 

 use. The preventive fluid thus contains both the dead bodies 

 of the bacilli and any toxins which may be in solution. It is 

 administered by subcutaneous injection, the dose, which varies 

 according to the "strength," being on an average about 7 '5 c.c. 

 Usually only one injection is made, sometimes two ; though the 

 latter procedure does not appear to have any advantage. The 

 method has been systematically tested by inoculating a certain 

 proportion of the inhabitants of districts exposed to infection, 

 leaving others uninoculated, and then observing the proportion 

 of cases of disease and the mortality amongst the two classes. 

 The results of inoculation, as attested by the first Indian 

 Commission, have been distinctly satisfactory. For although 

 absolute protection is not afforded by inoculation, both the 

 proportion of cases of plague and the percentage mortality 

 amongst these cases have been considerably smaller in the 

 inoculated, as compared with the uninoculated. Protection 

 is not established till some days after inoculation, and lasts for 

 a considerable number of weeks, possibly for several months 

 (Bannerman). In the Punjab during the season 1902-3 the case 

 incidence among the inoculated was 1*8 per cent, among the 

 uninoculated 7 '7 per cent, while the case mortality was 23 '9 and 

 60 '1 per cent respectively in the two classes, the statistics being 

 taken from villages where 10 per cent of the population and 

 upwards had been inoculated. 



2. Anti-plague Sera. Of these, two have been used as therapeutic 

 agents, viz. that of Yersin and that of Lustig. Yersin's serum is 

 prepared by injections of increasing doses of plague bacilli into the 

 horse. In the early stages of immunisation dead bacilli are injected 

 subcutaneously, thereafter into the veins, and, finally, living bacilli are 

 injected intravenously. After a suitable time blood is drawn off and 

 the serum is preserved in the usual way. Of this serum 10-20 c.c. 



