36

under these circumstances, rapidly produces spores. The aqueous humor
of a rabbit's and the sheep's eye is a particularly favourable medium
for the production of spores, and the ordinary bacillus gives, in it,
after twelve hours, beautiful spores, capable of resisting a temperature of
15° C. and 190° C. The asporagenous bacillus does not produce spores
even when cultivated in fresh, aerated aqueous humor. This, then, is
no temporary and passing change of the bacilli of charbon, but a
permanent hereditary change, and at present we are not acquainted with
any method by which we may endow the bacilli so modified with the
power of producing spores.

The appearance of cultures of asporagenous bacilli closely resem-
bles that of ordinary cultures of the bacillus. In broth they give
flocculi which are more easily broken down; the filaments of the
asporagenous bacillus are shorter and slightly thinner; they often
contain in their interior refractile grains, smaller than spores, and not
resistant to heat. At the commencement of the culture the filaments are
transparent and stain well; in proportion as the culture ages, many of
them become granular, swell up and stain badly. Cultivated on gelatine,
the asporagenous bacilli appear to liquefy it more rapidly than do
the ordinary bacilli. Broth in which the sporeless bacilli develop
is less coloured in the incubator, and gives less abundant crystals of
ammonio-magnesium phosphate than that which has nourished the
ordinary bacillus of charbon. The cultures of asporagenous bacilli
finally perish at 33° C. after a longer or shorter time, but generally
within a month. If after some days in the incubator we place them
at the temperature of the air, they remain alive for a much longer
period. Sporeless cultivations have been preserved in this manner sown
in broth for 155 days, at the end of which time they have given cultures;
they did not, however, contain any spores, and after heating at a tempera-
ture of 65° C. for fifteen minutes were sterilized. In other cases, these
asporagenous cultures remained in a cupboard in the laboratory, being
still alive after 81 days; a culture on nutrient jelly was still alive after
47 days. In these old cultures very few bacilli remained alive; to
resuscitate them they should be sown in large quantity, and after several
days we may perceive development taking place; the virulence of these
cultures without spores persists until they perish. A culture taken a
short time before its death or the death of its filaments is active and
destroys guinea-pigs and rabbits. In the mother cultures, on the contrary,
made in the presence of an antiseptic, there is a diminution of virulence,
as MM. Chamberland and Roux have long since pointed out. The
daughter cultures made from phenic cultures about eight days old—that
is, at the time when the loss of virulence is least marked—do not weaken
sensibly in successive cultures in broth. However, it seems that these