EXPERIMENTAL PHYSIOLOGY. 
131 
made many experiments upon the Bacillus anthracis, with the 
intelligent assistance of Dr. Jean Wesnessenky. 
The former researches of Toussaint, confirmed and explained 
by M. Pasteur, have demonstrated that the heating of the 
anthrax blood is susceptible of diminishing considerably the viru- 
lency of the bacilli which it contains. 1 have also demonstrated 
that this attenuation can be graduated, at will, so to speak, in 
varying the condition of the heating process. I will now prove 
that this heating, considered as a means of pseudo instantaneous 
attenuation of viruses, can bo applied to the liquids of artificial 
culture with much more success than to the natural fluids of the an¬ 
imal economy ; liquids whose manipulation is difficult and delicate, 
while that of the culture is as simple in the processes as it is sure 
in the results. I proceed as follows: 
In sterilized bouillon I sow anthrax blood. The matrasses 
are then placed in a thermostat, kept at the temperature -f- 42° to 
43°, as in the Pasteur process. Put instead of leaving the ma¬ 
trasses during twelve or thirteen days in the thermostat they are 
taken from it after about twenty hours, to be submitted in another 
thermostat to the temperature of -(- 47°, during one, two, three 
hours or even more. The operation is then finished; it lias not 
destroyed the vitality of the virulent agents of the culture, but 
they have lost more or less of their noeuity, according to the 
length of time they have been heated. 
The first step of the operation, the sojourn of twenty hours in 
the thermostat heated at -(- 43° corresponds to the stage of prolif¬ 
eration of the virus. There is nothing particular to remark upon 
the preparation of the cultures. 1 use light and very clear chicken 
bouillon, in which I place one drop of blood, rich in carbuncular 
batonnets. I prefer this to the spores of a previous culture in 
order to avoid the danger, undoubtedly imaginary, which would re¬ 
sult from the non-transformation of some of those very resist¬ 
ing agents. Indeed, the important point is to obtain, in the 
cultures, virulent agents under a form which leave them very 
accessible to the influence of heat. This indication is thoroughly 
realized in the conditions mentioned. The bouillon is soon 
cloudy by the formation of a mycelium, which breaks up in small 
