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Duclaux that spores exposed in a dry state may preserve their power of
vegetating for a month or more. The oxygen, which is necessary for
the development of the bacillus anthracis, may, under such circumstances,
contribute to its attenuation, or may even destroy it. Its action is more
particularly marked in adult bacilli, the spores bearing its presence
much better. Compressed oxygen also acts more energetically on the
rods or filaments than on the spores. When chemical germicides are
caused to act upon the microbes we still observe great differences
between the resistance of the rod and that of the spore; the adult bacilli
are killed more rapidly and with much smaller doses than are the spores.
Bromine, iodine, and chlorine may be used as germicides when we are
dealing with the baciilus anthracis even in the spore form. According
to Davaine 7 milligrammes of iodine sterilizes a litre of fluid in which
has been placed 1 centimetre cube of charbonous blood; it arrests the
development of charbonous microbes in culture media in which it has
been dissolved, and kills the spores after 24 hours' contact (Koch). Char-
bonous spores perish after an hour's exposure to chlorine water and the
rods are destroyed more quickly (Perroneito). Chlorine gas, 25 to 50 per
cent., kills the spores of charbon in a minute (Galtier), but in practice
these agents are little used. As to sulphurous acid, we know that it is
unable to sterilize the spores of charbon; and after the experiments of M.
Thionot we cannot count on sulphurous acid in large quantities used for
24 hours to destroy the microbe of charbon. Essence of turpentine
which has been considered as capable of destroying the bacillus and its
spores (Pasteur), may be inactive against the latter (Koch). Solution of
nitric acid must be used in high percentage to kill the spores, whilst a 2 per
cent. solution of hydrochloric acid should be sufficient to kill the bacilli
and their spores (Koch). A 5 per cent. solution of cresyl rapidly destroys
the adult bacillus; but the spores resist its action for a considerable time —
24 hours according to some, and more than 20 days according to
others (Esrnarch). With regard to the action of carbolic acid the follow-
ing remarks by Koch may be studied with benefit:—"Anthrax spores,
dried upon silk threads, were placed in carbolic solutions of various
strengths and kept in corked bottles. A thread was removed from time to
time, and planted on nutrient jelly. The following shows the results:—