32 NOTES ON MICRO-ORGANISMS. 
Klein mentions four facts as essential to establishing the cer- 
tainty of an organism being associated with disease :— 
1. Presence of the organism in the blood or tissues. 
2. Obtaining pure cultivations of this organism. 
. The retention of virulent properties, that is, being able to 
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originate the same complaint. 
4. The same organism must be found in the dead body. 
There has been much debate about the relations of pathogenic 
to ordinary septic organisms, and it remains an open question 
whether these last can under any conditions promote a state of 
the body of animals inducing an infectious disease. Dr. Hans 
Biichner some years ago positively asserted that he had trans- 
formed the hay bacillus into the anthrax bacillus, but there is 
every reason to doubt the fact, especially as Biichner was experi- 
menting on anthrax at the time, and so probably obtained impure 
cultures. Klein points out besides, that there are very consider- 
able morphological differences in the two organisms, Bacillus 
anthracis, for instance, has never been seen in a motile form. 
The only established case of a common septic organism being 
transformed into a pathogenic one is in the case of a mould 
called Aspergillus. Spores of this mould were introduced into 
the jugular vein of a rabbit, which died 36 hours after, and a 
free growth of the mould was found in various parts, especially 
the kidneys. Any organism that has an effect in the system pro- 
bably possesses it ad zzitio, and does not acquire it. 
Generally speaking, the temperature of the human body is a 
very favourable one for the development of micro-organisms. 
Where fevers are accompanied by an organism, it may be pre- 
sumed that the rise of temperature first favours the growth, and 
that later a temperature is reached that has an adverse effect ; and 
that every Bacterium has its most favourable point in such a 
range of temperature. It is evident that were the favourable and 
unfavourable degrees of temperature known for each pathogenic 
organism, that additional light would be thrown upon the treat- 
ment of certain fevers. 
