RESISTANCE AGAINST BACTERIA. 333 



The weakening of personal vigor will do more toward increas- 

 ing germ diseases than a relaxing of the rules which try to 

 prevent the distribution of bacteria. We are beginning to be- 

 lieve that in regard to most infectious diseases the personal re- 

 sistance of the individual will enable him to repel an attack 

 even after he is exposed, provided his personal resistance be at 

 its maximum ; while a weakened resisting power will result in 

 his yielding to the first attack of an invading bacterium. For 

 some of the less violent diseases (tuberculosis) this is much 

 more emphatically true than for other diseases (anthrax). 

 Now it is not possible to hope that we shall ever be able 

 to exterminate all pathogenic bacteria, and even if we did, 

 other forms would doubtless take their places. Since we can- 

 not exterminate them, it follows that all individuals will, at 

 some time, be exposed to the attack of some of the germ dis- 

 eases. Manifestly, then, the best means of elevating the health- 

 fulness of the race is by raising the resisting power rather than 

 by the vain attempt to destroy pathogenic bacteria. All this 

 may be admitted without at all detracting from the value of 

 the sanitary rules advocated by health boards. 



INDIVIDUAL RESISTANCE AMONG ANIMALS. 



These facts are of even more importance in the case of para- 

 sitic diseases of animals than in the case of human diseases. 

 It is of more importance that the agriculturist should under- 

 stand them, as he endeavors to make a fight against the 

 diseases of domestic animals, than it is for the physician or 

 the veterinarian who tries to cure the disease. With animals, 

 as with man, the individual resisting power is variable, at least 

 for some of the most common diseases. When a lot of pigs 

 are attacked by that very fatal disease, hog cholera, some of 

 the lot escape with no signs of the disease, showing a superior 

 resisting power. Undoubtedly the resisting power of animals 

 is due to a proper physical vigor, little understood, it is true, 



