70 ESSENTIALS OF BACTERIOLOGY. 



Chemotaxis. This attraction of leucocytes towards bacteria 

 by means of their chemical products is called chemotaxis. 



These proteids when injected by themselves, i. e., sterilized 

 cultures, also produce chemotaxis. When the alexine is not 

 strong enough to destroy the bacterium it develops and finally 

 destroys the action of leucocytes. 



Toxines are repellant, producing a " negative chemotaxis." 



Cure of Infectious Diseases with Bacteria and their Products. 

 Antagonism. It has been known, and is easily demonstrated, 

 that the growth of one bacterium near another results often in 

 the destruction of one, a direct antagonism existing. 



Rabbits suffering with anthrax were injected with large quan- 

 tities of streptococcus of erysipelas (pyogenes), and a cure 

 effected, those not so treated dying. 



Several other diseases have been so treated in animals with 

 interesting results. 



Toxalbumen Injections. When diphtheria is produced in 

 animals, an injection of the toxalbumen of diphtheria will cure 

 the same, and if injected first, diphtheria will not arise. 

 Tetanus has been cured and prevented in a similar manner. 



Tuberculin. Dixon, in 1889, found, by injecting products of 

 tubercle cultures in glycerine, that Guinea-pigs so treated, suffer- 

 ing from tuberculosis, were cured ; control animals dying. Koch, 

 in 1890, applied this method to man, but without success. 



Koch's Rules in Regard to Bacterial Cause of Disease, 

 Before a microbe can be said to be the cause of a disease, it 

 must 



First. Be found in the tissue or secretions of the animal suf- 

 fering from, or dead with the disease. 



Second. It must be cultivated outside of the body on artificial 

 media. 



Third. A culture so obtained must produce the disease in 

 question when it is introduced into the body of a healthy 

 animal. 



Fourth. The same germ must then again be found in the 

 animal so inoculated. 



