298 THE LIFE OF PASTEUR 



curable to bacteridia, the result was worse still : the microbe 

 disappeared in forty-eight hours. 



"Is not that," said Pasteur with the gift of comparison 

 which made him turn each failure into food for reflection" an 

 image of what we observe when a microscopic organism proves 

 to be harmless to a particular animal species? It is harmless 

 because it does not develop within the body, or because its 

 development does not reach the organs essential to life." 



After trying other culture mediums, Pasteur found that the 

 one which answered best was a broth of chicken gristle, 

 neutralized with potash and sterilized by a temperature of 

 110 C. to 115 C. 



" The facility of multiplication of the micro-organism in 

 that culture medium is really prodigious," wrote Pasteur in a 

 duplicate communication to the Academies of Sciences and of 

 Medicine (February, 1880), entitled Of Virulent Diseases, and 

 in particular that commonly called Chicken Cholera. " In a 

 few hours, the most limpid broth becomes turgid and is found 

 to be full of little articles of an extreme tenuity, slightly 

 strangled in their middle and looking at first sight like isolated 

 specks ; they are incapable of locomotion. Within a few days, 

 those beings, already so small, change into a multitude of 

 specks so much smaller, that the culture liquid, which had at 

 first become turgid, almost milky, becomes nearly clear again, 

 the specks being of such narrow diameter as to be impossible to 

 measure, even approximately. 



" This microbe certainly belongs to quite another group than 

 that of the vibriones. I imagine that it will one day find a 

 place with the still mysterious virus, when the latter are suc- 

 cessfully cultivated, which will be soon, I hope." 



Pasteur stated that the virulence of this microbe was such 

 that the smallest drop of recent culture, on a few crumbs, was 

 sufficient to kill a chicken. Hens fed in this way contracted 

 the disease by their intestinal canal, an excellent culture 

 medium for the micro-organism, and perished rapidly. Their 

 infected excreta became a cause of contagion to the hens which 

 shared with them the laboratory cages. Pasteur thus 

 described one of these sick hens 



" The animal suffering from this disease is powerless, stag- 

 gering, its wings droop and its bristling feathers give it the 

 shape of a ball ; an irresistible somnolence overpowers it. If 

 its eyes are made to open, it seems to awake from a deep sleep, 



