276 PASTEUR : THE HISTORY OF A MIND 



somewhat dogmatic style, general and without details, 

 which he still affected at this time. I speak of his 

 study of chicken cholera, concerning which I have as 

 yet said only a word, and which I have reserved for 

 the following chapter, because it is a disease which has 

 the closest analogies with the virus diseases. We shall 

 see, in reality, that this cholera, like smallpox, is some- 

 times epidemic and deadly; sometimes chronic and 

 harmless; that transferred from the chicken to the 

 guinea-pig, like the cowpox transferred from the cow 

 to the man, it may become an artificial and fixed dis- 

 ease, preserving its character indefinitely. 



II 

 CHICKEN CHOLERA 



"Sometimes there breaks out in the poultry-yard a 

 disastrous disease, commonly known as chicken cholera. 

 The animal which is a prey to this infection is without 

 strength, trembles and has drooping wings. The feath- 

 ers of the body are ruffled giving it the form of a ball; 

 an unconquerable drowsiness overpowers it; if forced 

 to open its eyes it appears to waken from profound 

 slumber; soon the eyes close again, and in most cases, 

 the animal does not change its position until death comes, 

 after a dumb agony. At most it sometimes shakes its 

 wings for a few seconds." 1 



These singular symptoms are due to the development 

 of a microbe which can be isolated in cultures in neutral- 

 ized chicken bouillon. Sowing in this liquid a drop 

 of the blood of a chicken which had died of the cholera, 



1 Sur le cholera des poules. Comptes rendus de 1'Academie des 

 Sciences, 1880. 



