REMARKS ON MICRO-ORGANISMS. 
857 
gradual modification. Instead of the cloud at the bottom of 
the vessel, a scum began to make its appearance—at first 
greasy-looking and easily broken up—constituting, so lar 
appearances went, an intermediate form between the tuo 
organisms; and in course of time the scum became dryer 
and firmer, and at length the modified Bacillus anthracis w as 
found to be capable of growing in an acid hay infusion, a 
to present in every respect the characters of the hay-bacillus. 
The converse feat of changing the hay-bacillus into the Bacillus 
anthracis proved very much more difficult. A great number 
of ingenious devices were adopted by Buchner, who was, 
nevertheless, continually baffled till at last he attained success 
in the following manner. Having obtained l be blood of a 
healthy animal under antiseptic precautions, and defibi mated 
it also antiseptically, and having arranged his appparatus so 
that the pure defibrinated blood, which was to be the cul¬ 
tivating medium, should be kept in constant movement so as 
to continually break up the scum, and also keep the red 
corpuscles in perpetual motion so as to convey oxygen to all 
parts of the liquid—in this way imitating, to a certain extent, 
the conditions 1 of growth of the Bacillus anthracis outside the 
an ma body withhi which the hay-bacillus could not be got 
bv any means to develop-he proceeded to cultivate through 
numerous successive generations. A transitional form soon 
made its appearance; but the change advanced only to a 
limited degree, so that further progress by this method became 
hopeless. The modified form hitherto obtained faded entirely 
to grow when injected into the blood of an animal. On the 
contrary, it was in a short time completely eliminated from 
the system, just like the ordinary hay-bacillus. It had, 
however, been observed by Buchner that spores had never 
been formed by the bacillus growing in the defibrinated 
blood • and it occurred to him that, perhaps, if it were trans¬ 
ferred to extract of meat, and induced to form spores here, 
the modified organism might yet grow in the blood of a living 
animal. The carrying out of this idea was crowned w^th 
success ; and, both in the mouse and in the rabbit, Buchner 
succeeded by injecting various different quantities containing 
the organism in different animals. When large quantities 
were introduced, the animals died rapidly from the merely 
chemical toxic effects of the injected liquid; but, in some 
instances after the period for these primary effects had passed 
a " disease supervened-attended, as in anthrax, with 
great swelling of the spleen, the blood of which was founc 
peopled as in that affection with newly formed bacilli; and 
the spleens affected in this way were found to communicate 
