COMBATING PARASITIC BACTERIA. ' 193 



antidote for the poison of snake bites, since it has 

 appeared that in this kind of poisoning the body 

 will develop an antidote to the poison if it gets a 

 chance. Horses have been treated in the same 

 way as with the diphtheria poison, and in the 

 same way they develop a substance which neu- 

 tralizes the snake poison. Other diseases are 

 being studied to-day with the hope of similar 

 results. How much further the principle will go 

 we can not say, nor can we be very confident that 

 the same principle will apply very widely. The 

 parasitic diseases are so different in nature that 

 we can hardly expect that a method which is satis- 

 factory in meeting one of the diseases will be very 

 likely to be adapted to another. Vaccination has 

 proved of value in smallpox, but is not of use in 

 other human diseases. Inoculation with weak- 

 ened germs has proved of value in anthrax and 

 fowl cholera, but will not apply to all diseases. 

 Each of these parasites must be fought by special 

 methods, and we must not expect that a method 

 that is of value in one case must necessarily be 

 of use elsewhere. Above all, we must remember 

 that the antitoxines do not cure in themselves; 

 they only guard the body from the weakening 

 effects of the poisons until it can cure itself, and, 

 unless the body has resisting powers, the anti- 

 toxine will fail to produce the desired results. 



One further point in the action of the anti- 

 toxines must be noticed. As we have seen, a 

 recovery from an attack of most germ diseases 

 renders the individual for a time immune against 

 a second attack. This applies less, however, to a 

 recovery after the artificial inoculation with anti- 

 toxine than when the individual recovers without 

 such aid. If the individual recovers quite inde- 



