126 Lectures on Bacteria. [^ xii. 



nection between the Bacillus to which the rods belong and the 

 disease known as anthrax was first distinctly pointed out by 

 Davaine in 1863, and this view of the matter, though it has been 

 opposed on various grounds, is now accepted. It has been 

 distinctly proved that the disease makes its appearance only 

 when the Bacillus has found its way into the blood, and that the 

 artificial introduction of the Bacillus into the blood results in 

 the characteristic infection, the sickening of the animal. The 

 infection follows if the living Bacillus is introduced directly 

 into the blood by intentional inoculation, anthrax by inocula- 

 tion, or unintentionally through wounds of the skin, anthrax 

 by wounds, or through the uninjured mucous membrane of the 

 intestinal canal, intestinal anthrax. It is effected both by means 

 of living rods, and by spores, the latter then germinating in 

 the blood or in the intestine. In both cases it is a matter 

 of indifference whether the matter used for infection is obtained 

 direct from a diseased animal or from a culture, such as will 

 be described presently, which has been kept free from every 

 trace of any product of animal disease. The Bacillus, when 

 it has died of itself or been killed, is incapable of producing 

 the infection. 



When once the Bacillus has found its way into the blood of 

 an animal capable of the infection, it grows and multiplies in the 

 rod-form and spreads partly by its own growth, partly by the 

 movement of the blood which carries the rods along with it in 

 the manner described above. In proportion as this takes place, 

 the sickness increases till at length death supervenes. The 

 minutest possible quantity of the living Bacillus is sufficient to 

 set these processes going. A guinea-pig, for example, dies with 

 the symptoms which have been described in forty-eight hours 

 after a quantity of spores or rods, too small to be visible with a 

 pocket-lense, is introduced into the skin on the point of a needle 

 by a puncture too slight to draw blood. 



Anthrax by inoculation and anthrax by a wound are alike 

 caused by the introduction of both spores and living rods. 



