138 
M. L. PASTEUR. 
its purity. This culture left an extract which was re-dissolved in 
2 cubic centimeters of pure water, all of which was afterwards 
injected under the skin of a fresh hen. Several days after, this 
bird was inoculated with a very strong virus, took the cholera and 
died nndcrconditions similar to those of the non-vaccinated chickens. 
This kind of experiment carries us to an observation as new 
as it is curious, in its pathological connections : 
When one injects under the skin of a fresh hen, in good 
health, the extract of a filtrated culture of the microbe, corres¬ 
ponding to a very abundant development of the parasite, the hen 
(after a nervous disorder which passes off in fifteen minutes, and 
sometimes is only manifested by a slightly hurried respiration 
and a motion of the beak, which opens and closes several times) 
assumes the shape of a ball, remains immobile, refuses to eat and 
has a desire for sleeping, very marked, as in the case of the dis¬ 
ease produced by inoculation of the microbe. The only differ¬ 
ence consists in the fact that the sleep is lighter than in the real 
disease, the hen waking up at the slightest noise. This somnolence 
lasts about four hours, after which the bird returns to perfect 
health, as if nothing had happened.* 
I have several times repeated that experiment, with the same 
* Here is the observations of one experiment: 
The 4tli of March, at 10:30, a fresh hen is inoculated under the skin with 
the extract of a culture of the microbe of chicken cholera, 120 cubic centimeters 
in volume. After some moments of hurried breathing, the tougue is agitated in 
her open beak. After about fifteen minutes, tendency to sleep. The beak is 
closed, the hen quiet, immobile, nearly gathered into a ball; her eyes are closed, 
but open at the slightest noise, only to close again. She sleeps, but easily 
wakes up, only to fall back to her sleep again. 
12 o’clock, M.: Same condition ; refuses to eat; is very sleepy. She is 
easily wakened. She has the aspect of diseased hens. Another hen, sick, inocu¬ 
lation the day before, and which will be dead to-morrow, is placed alongside of 
her. It is difficult to say which is the sickest, though the second sleeps the 
soundest. 
1:30 P.M.: Always sleeping. Head heavy and droopiug ; body in a ball; 
immobile ; does not eat; awakes readily. 
2 o’clock, P. M : Same condition. Sometimes raises her ^head ; opens her 
eyes as if waking from a dream. 
3 o’clock, P. M.: Regains her vivacity ; begins to eat; carries her head 
up ; no more sleepiness ; dresses her feathers. It is all over. Nothing else par¬ 
ticular to observe. Perfect health. The effect has lasted four hours. 
