246 SCIENCE PROGRESS. 



requires air for its existence, on the other air acts pre- 

 judicially. 



The anthrax bacillus, he found, would grow readily in 

 certain animals, the ox, the sheep, the rabbit, the guinea- 

 pig, not so readily in the dog, whilst he found that fowls were 

 not at all vulnerable to its attacks. What was the reason 

 for this difference ? The answer to this question, as worked 

 out and given by Pasteur, so well illustrates his method ol 

 reasoning and procedure that it may be given in some de- 

 tail. It was found that by subjecting the anthrax bacillus 

 to a temperature of 44 C. ( 1 1 1 • 2 ° F.), it was rendered in- 

 capable of developing. The temperature of the fowl — 

 41° to 42"' C. (io5'8° to io7*6° F.) — though not quite so 

 high, may help the tissues to deal with the micro-organism 

 and prevent its development taking place in the body ol 

 this bird. " No doubt," he said, "life to a parasite in the 

 body of an animal would not be as easy as in a cultivating 

 liquid contained in a glass vessel." Was this temperature, 

 plus the action of the tissues, the cause of the non-develop- 

 ment of the anthrax bacillus ? The now classical experi- 

 ment of cooling the blood of the hen — by placing its feet in 

 water maintained at a temperature of 25° C. until it came 

 down to the temperature of the human body — having pre- 

 viously inoculated the bird with the bacillus anthracis, was 

 made with the result that "at the end of twenty-four hours 

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

 bacteria". The converse experiment was then tried. "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 35 C. 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." 



In these experiments and the deductions made therefrom, 

 we have the groundwork of Pasteur's great work on protec- 

 tive vaccines and vaccination. 



