856 REMARKS ON MICRO-ORGANISMS. 
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 Bacterium 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 pro¬ 
ducing 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 luxuriance; 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 tem¬ 
peratures, which is not the case with the Bacillus anlhracis 
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 antliracis produces a delicate cloud at the bottom of 
the vessel, increasing slowly. Nothing daunted by these 
apparent essential differences, Dr. Buchner has laboured with 
indomitable 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 com¬ 
munication with a cultivating vessel, so that any cultivation 
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 apparatus, Buchner pro¬ 
ceeded to cultivate the isolated Bacillus anthracis in extract of 
meat for several hundred successive generations. As an early 
result of these experiments, he found that the bacillus lost its 
power of producing disease in an animal inoculated with it. 
Up to this point he is confirmed by Dr. Greenfield, who has 
found that, when the bacillus anthracis is cultivated in aqueous 
humour, after about six generations it loses its infective pro¬ 
perty. Then, as Buchner's experiments proceeded, the ap¬ 
pearance of the growing organism was found to undergo 
