33 



death, lost its poisonous properties entirely in a few hours, 

 when exposed in a thin layer to the air. Now, since the 

 vibrios likewise lose their vitality in a few hours in the 

 presence of free oxygen, Pasteur insists that the loss of 

 virulence in the fluid is due solely to the enforced inac- 

 tivity of the contained vibrios. Yet he is inclined to 

 the belief that just as the alcoholic fermentation of grape 

 sugar is a vital phenomenon manifested by any one of 

 several species of fungi, so the production of septic sub- 

 stances may accompany the vital activity of any one of 

 several different bacteria. 



Pasteur further reports that among the organisms usu- 

 ally present in ordinary water is one identical morpho- 

 logically with the bacterium termo, but physiologically 

 distinguished by the fact that its injection from an iso- 

 lated cultivation under the skin of a rabbit is followed 

 by abscess formation at the site of puncture. Injec- 

 tion of the same organisms directly into the circulation, 

 or in several places subcutaneously, is followed by the 

 formation of abscesses in lungs and liver ; by fever and 

 death in short, by pyaemia. A piece of the liver or 

 lung develops in a culture liquid, the same micrococcus 

 in great numbers. Such liquid, if previously boiled 

 however, so as to destroy the organisms therein contained, 

 causes, upon subcutaneous injection, abscesses as before, 

 but without general infection of the animal. He rejects, 

 therefore, for pyaemia as for septicaemia, the agency of an 

 unorganized, soluble septic agent, and considers the bac- 

 teria alone responsible for septic infection. 



Markedly different was the reception accorded to a 

 monograph published in 1878, by a then almost un- 

 known young German physician, Robert Koch. He sur- 

 mounted, by improvements in technique, some of the 

 hitherto insuperable difficulties in the recognition and >n- 

 vestigation of bacteria improvements which confer such 

 evident and extreme advantages that they have become 

 absolute necessities for original research in this field ; in- 

 deed so many errors of commission, as well as of omission, 

 have been thereby detected in other methods, that one is 



