ANTISEPTIC SURGERY 171 



with fatal results. These animals, although be- 

 traying no obvious signs of the disease, may never- 

 theless transfer it to fowl, thus playing the part 

 of what we now would call "carriers" of the disease. 

 Pasteur's experiments had to be interrupted for 

 several weeks and when he recurred to his old cul- 

 tures which had been set aside and attempted to 

 carry them on by inoculating new media and fresh 

 fowl he found that growth in the new media was 

 very slow or absent, and that the inoculated fowl 

 were apparently unaffected. Being about to throw 

 the old cultures away and begin anew it occurred 

 to Pasteur to inoculate these fowl with a fresh, 

 virulent culture of the bacilli. To his surprise 

 nearly all of these fowl withstood the disease, 

 whereas new fowl recently purchased, which were 

 inoculated with the same fresh culture, succumbed 

 in the usual way. The idea immediately suggested 

 itself that the first lot of fowl had been rendered 

 immune by their previous inoculation with the old 

 cultures of the germ. We may well believe that 

 there was excitement in the Pasteur laboratory over 

 this striking and unexpected result! Further ex- 

 periments which were made served to confirm the 

 conclusion that by proper culture the chicken 

 cholera germ could be weakened so that when it was 



