338 PROFESSOR JOSEPH LISTER. 
domain of pathology; and this also has reference to the 
Bacillus anthracis. ‘The investigator in this instance is Dr. 
Buchner, assistant physican in Munich. It is well known 
that the Bacillus anthracis is morphologically identical with 
an organism frequently met with in infusion of hay, 
which may be termed hay-bacillus. Such being the case, it 
occurred to Dr. Buchner that they might be merely one 
and the same organism modified by circumstances. For my 
own part, I am quite prepared to hear of such modifying 
influence being exerted upon bacteria, having made the 
observation several years ago that, when the Bacterrum 
lactis had been cultivated for some time in unboiled urine, 
it proved but a feeble lactic ferment when introduced again 
into milk. Its power of producing the lactic fermentation 
had been impaired by residence in the new medium. In the 
case before us, indeed, the physiological difference between 
the two organisms seems, at first sight, so great as to forbid 
the idea of anything other than a specific difference. The 
Bacillus anthracis refuses to grow in hay-infusion, in which 
the hay-bacillus thrives with the utmost Inxuriance; and 
conversely, the hay-bacillus is utterly incapable of growing 
in the blood of a living animal, whether introduced in small 
or in large quantities. ‘The hay-bacillus is remarkable for 
its power of resistance to high temperatures, which is not 
the case with the Bacillus anthracis. The latter is destroyed 
by a very slight acidity of the liquid of cultivation, or by 
any considerable degree of alkalinity, whereas the former 
survives under such conditions. Both will grow in diluted 
extract of meat, but their mode of growth differs greatly. 
The hay-bacillus multiplies rapidly, and forms a dry and 
wrinkled skin upon the surface, while the Bacillus anthracis 
produces a delicate cloud at the bottom of the vessel, in- 
creasing slowly. Nothing daunted by these apparently 
essential differences, Dr. Buchner has laboured with indo- 
mitable perseverance, by means of experiments carried on 
in Professor Nageli’s laboratory, to solve the double problem 
of changing the Bacillus anthracis into hay-bacillus, and the 
converse. Having devised an ingenious apparatus by which 
a large reservoir of pure cultivating liquid was placed in 
communication with a cultivating vessel, so that any culti- 
vation could be drawn off by simply turning a stop-cock, 
and further cultivating liquid supplied to the organisms 
remaining in the vessel by a mere inclination of the appa- 
ratus, Buchner proceded to cultivate the isolated Baczllus 
anthracis in extract of meat for several hundred successive 
generations. As an early result of these experiments, he 
