210 LOUIS PASTEUR. 



This idea conducted Pasteur and his assistants to new 

 researches. ' If the blood of a fowl was cooled,' they 

 asked, ' could not the splenic fever parasite live hi this 

 blood?' 



The experiment was made. A hen was taken, and, 

 after inoculating it with splenic fever blood, it was 

 placed with its feet in water at 25 degrees. The 

 temperature of the blood of the hen went down to 

 37 or 38 degrees. At the end of twenty-four hours 

 the hen was dead, and all its blood was filled with 

 splenic fever bacteria. 



But if it was possible to render a fowl assailable 

 by splenic fever simply by lowering its temperature, 

 is it not also possible to restore to health a fowl 

 so inoculated by warming it up again ? A hen was 

 inoculated, subjected, like the first, to the cold-water 

 treatment, and when it became evident that the fever 

 was at its height it was taken out of the water, 

 wrapped carefully in cotton wool, and placed in an 

 oven at a temperature of 35 degrees. Little by little 

 its strength returned; it shook itself, settled itself 

 again, and in a few hours was fully restored to health. 

 The microbe had disappeared. Hens killed after 

 having been thus saved, no longer showed the 

 slightest trace of splenic organisms. 



How great is the light which these facts throw 

 upon the phenomenon of life in its relation to ex- 

 ternal physical conditions, and what important in- 



