216 
M. CHAMBERLAND AND ROUX. 
solution of 1-900 the bacteridie threads remain alive for quite a 
long time, as proved by the cultures which can be made of them, 
even after the expiration of several months. During the entire 
duration of the experiment they give no germs, and the virulency 
continues to diminish. For instance, the culture of thready bac- 
teridies, which have remained for a month in contact with a 
phenic solution of 1-900, kills rabbits and guinea pigs. A culture 
of three months does not kill rabbits. In these cases the loss of 
the virulency is less rapid than in the case where the bacteridies 
are in presence of the antiseptic. It is only a short time before 
the death of the filaments that this diminution of virulency for 
the rabbits can be observed. 
The condition essential to reduce the virulency of the bac¬ 
teridie of anthrax, either by the method of cultures aj: 42—43°, 
or by that which uses the antiseptics, is the absence of spores in 
the threads submitted to the continued action of air, of heat, or 
of various other chemical agents. The spore is the form of resist¬ 
ance of the bacteridie; it, so to speak, removes it from the action 
of the surrounding medium, and preserves the properties of the 
thread from which it comes. Notwithstanding this resistance to 
the external agents, the germ of bacteridie can be modified and 
reduced in its virulency, as the thread itself. 
Well-formed spores of bacteridie, about fifteen days old, are 
exposed to the contact of sulphuric acid at two per cent., and 
to the temperature of 35° in closed tubes, being frequently 
shaken to be sure of the contact of air with the spores. Every 
second day a small quantity of these spores are placed in a bouil¬ 
lon of veal, slightly alkaline. The cultures thus obtained, in the 
first days, kill rabbits and guinea pigs. The culture of the 
eighth or tenth day kills the guinea pigs, but remains harmless to 
the rabbits; that of the fourteenth day remains active only in a 
few of the pigs inoculated. The bacteridies thus obtained pro- 
duce numerous germs rapidly, and preserve their reduced viru¬ 
lency in the successive cultures. 
But it is remarkable that the cultures formed from the spores 
treated by sulphuric acid, and which have lost some of their viru¬ 
lency for rabbits, has preserved it for sheep, and kills them in 
