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 Be'champ 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, Pettenkof er and Nageli, 

 set forth this telluric theory of disease, and several 

 facts confirm it. It explains why intermittent fever, or 



