Louis Pasteur: His Life and Labours

swine fever (rouget). Here, again, it is a microbe which causes the disorder. This microbe was first perceived by Thuillier, in a little commune of the Département de Vienne, when examining t

all drop of the preceding cultivation being always taken for seed. Inoculations from these last cultivations produced

having had recourse to the oxygen of the air to attenuate the virulence of the microbe, Pasteur made some experiments in vaccination. Some pigs which had been vaccinated remained in the canton of Bollène, under the supervision of M. Maucuer, the owners having pledged themselves to keep their vaccinated pigs

plication of vaccines to different breeds requires still further

the atmospheric oxygen, for weakening the virulen

. If this microbe has lived in any species of animal-that is to say, if several times over it has passed from the body of one individual into that of another of the same kind, without having been subjected to any sensible exterior influence during its passage-we may consider that the virulence of this parasite has reached a fixed and maximum state for the individuals of that race. The splenic fever parasite pertaining to sheep, for instance, varies little from one subject to another or from one year to another in the same country; this must be attributed, doubtless, to the fact that, in its successive passages thro

hown to be harmless for adult guinea-pigs, but it kills rapidly guinea-pigs only some hours or days old. In following out this inoculation from young guinea-pigs, we have seen the virulence increase, and easily arr

that the microbe, after having increased its virulence by successive passages through the bod

rd to the microbe which is deadly to rabbits. From this arises the all-important consequence, that the habit of living in one species (the guinea-pig) at a definite corresponding d

contains the secret of a new method of attenuation, which can be applied to som

of swine fever, the pigeon dies in an interval of six or eight days

g itself into a ball, and of somnolence, which are the habitual characteristics of the disease, appear in a much shorter time than with the first pigeons of the series. Death likewise comes on

esult. Rabbits inoculated with the infectious products of a pig that has died of the

s. The cultures of the blood of these rabbits in sterilised media become progressively easy and more abundant. The microbe itself changes its aspect somew

, it is found that the virulence has been progressively diminishing from the first rabbit to the following ones. Very soon the blood of