THE MICROBES OF HUMAN DISEASES. 167 
the nature of anthrax, of which we have spoken above. 
These observers collected earth in the neighbourhood of 
trenches in which animals which had died of anthrax 
had been buried, and found that not only on the surface, 
but at some depth, this earth was full of bacteridia 
(Bacillus anthracis), and also of many other microbes 
or germs, of which the inoculation might produce more 
or less dangerous diseases in animals. In order to 
procure earth in a more perfect state of division, it 
occurred to Pasteur to collect the excrement of earth- 
worms, which consists almost exclusively of clay, rich 
in humus or vegetable earth, on which the worms 
are nourished. This earth, after passing through the 
intestinal canal of worms, still contains microbes which 
have not lost their virulence. As we have already 
said, spring water, on issuing from the soil, contains 
microbes which it has acquired in filtering through 
geological layers; and we have also mentioned the 
living microbes of chalk, dating, as Béchamp believes, 
from the secondary epoch. 
Telluric and Diblastic Theories.—Hence, it is in- 
telligible that a theory should have been formed, 
ascribing most epidemic diseases to the influence of 
microbes of the soil, which can at a given moment 
enter the human body, first by penetrating into the 
lungs and digestive organs, and thence into the blood. 
Two German discoverers, Pettenkofer and Négeli, 
set forth this telluric theory of disease, and several 
facts confirm it. It explains why intermittent fever or 
