352 BACTERIA IN INFECTIOUS DISEASES. 



taken from the heart, or in the internal organs of 

 a mouse killed by such an injection ; nor did its 

 blood, taken from the right auricle, cause the death 

 of other mice into which it was injected. The 

 symptoms of poisoning in these cases were more 

 or less severe according to the amount of septic 

 material introduced, and no doubt were due to the 

 chemical poison, sepsin, which is present in putrid 

 blood. But when small quantities of this putrid 

 blood were injected, it happened that, while a 

 majority of the little animals experienced no per- 

 ceptible effects from the injection, a certain num- 

 ber fell ill at the end of twenty-four hours, and 

 death occurred in forty to sixty hours from the 

 time of inoculation. 



In these cases the symptoms and post mortem 

 appearances were of a definite character, and the 

 disease was proved to be infectious. This was 

 shown by inoculation from mouse to mouse of a 

 minute quantity of blood, one-tenth of a drop 

 was ample. Koch says : " I have performed these 

 experiments on fifty-four mice, and have always 

 obtained the same result. Of these, seventeen 

 inoculations were made in succession." We must 

 refer the reader to Koch's work for the symp- 

 toms and pathological appearances which charac- 

 terize this infectious disease 1 ; its etiology alone 

 concerns us here. 



The certainty with which the infective material 

 can be carried from one animal to another is said 



1 Traumatic Infective Diseases. 



