SPIRILLA 323 



plus vibrios. Or, inject a mixture of one loopful (2 mgr. 

 of recent agar culture and I c.c. of broth containing o-ooi 

 c.c. of anti-cholera serum into the peritoneum of a guinea- 

 pig. Remove some fluid at regular intervals and examine. 

 If above reaction is got, then said to be positive, and in case 

 described, organism is proved to be true cholera spirillum. 

 If the latter is used against an unknown serum, then the 

 anti-power of the serum can be determined and, if positive, 

 by using various dilutions, the bacteriolytic power. 



Immunization. A guinea-pig is easily immunized by 

 repeated injections of non-fatal doses of dead spirilla ; 

 later small doses of living organisms may be used. A high 

 degree of immunity is thus developed, and the blood 

 serum of such an animal (anti-cholera serum) when 

 injected into another guinea-pig has marked protective 

 power. This is not due to any antitoxic substances, but 

 to antibacterial power. Cholera-immune serum is thus 

 bacteriolytic, not antitoxic. This power is specific, and 

 does not apply to other closely related organisms. 



Haffkine's Vaccine. First vaccine : Attenuated virus 

 by long cultivation at 39 C. or by other methods. 

 Second vaccine : Given five days later, of virulent virus 

 (by passage through guinea-pigs). Both given sub- 

 cutaneously. Lately has given only one, and that the 

 " virus exalte." General conclusions as to efficacy : 

 (i) Protective effect of anti-cholera vaccine commences 

 soon after operation and increases rapidly for first four 

 days, and lasts fourteen months, after which it diminishes 

 and completely disappears. Larger doses cause longer 

 effects. (2) During period of its activity, the number of 

 cases among vaccinated is one-tenth of number among 

 others. (3) Mortality among those attacked differs but 

 little, and the course of the disease is not affected by 

 the previous inoculation. 



Isolation. 



i. From Faces. Make pre-culture in peptone water. 

 (a) Inoculate peptone water inErlenmeyer flasks (i loopful 

 in each), (b) In eight hours, if a film appears or not, 

 make hanging drop from surface, and if you get fish trains, 

 dry and stain to see if form is typical, (c) Subculture 

 from film on gelatin plates, and smear over agar plates. 



