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13
unquestionably modifies the toxic action of the gastric juice. An
increase in temperature, above the optimum for the fungus, increases
the toxicity of the juice to this species. Thus, while the juice had
no inhibitory effect on the development of spores of Penicillium
notatum and P. frequenlans at the optimum temperature for these
fungi, a rise in temperature to 37° C. destroyed the vitality of
these spores but did not kill the spores of the thermophilous
species.
A similar modifying effect of temperature on the toxic properties
of chemicals has been noted before. HEIDER (26) found that the
toxic action of certain chemicals on the spores of Bacillus anthracis
increases with a rise in temperature. Brooks (3) worked with
Botrytis vulgaris, Monilia fructigena, Aspergillus niger, Mucor mucedo,
and »Penicillium glaucum», and found that the deleterious action of
copper sulphate, sulphuric acid, and nitric acid very rapidly
increased with the rise of temperature. The injurious effects were
in all instances least at the optimum for the fungus.
Seen in the light of the above mentioned facts, it appears very
probable that the combined action of body temperature (in the case
of warm-blooded animals) and gastric juice, kills the spores of fungi
with low optimum temperature when these are passing through the
alimentary canal. The circumstance that the toxic action of the
juice is least at the optimum temperature of the fungus, enables
the thermophilous species to pass through alive. The curious fact
that none of the extremely common green species of Penicillium,
the majority of which have a comparatively low optimum temperature,
could be isolated from human faeces, becomes intelligible as well.
On the other hand, the presence of these particular species in faeces
of cold-blooded animals is to be expected, since the toxic action of
the gastric juice cannot be raised to any considerable degree in
these animals with low body temperature. The finding of Penicil-
lium notatum in lizard and P. frequentans in frog tends to substant-
iate this view. |
As was stated above, WEIGMANN and WOLFF (69) found Penicillium
brevicaule in the faeces of cow. It is interesting to note that this
species grows vigorously at 37? C. (Praur 50, THom 63). FERGUSON
(14) failed to recover Agaricus campestris in the faeces of rabbits
when spores of this fungus had passed through the digestive tract
of the animal. If the failure is to be ascribed to the above mentioned
facts about the killing of moulds of low optima is not certain, but
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