36 SOURCES OF INFECTION. 



sioii that very slight currents convey microbes from the margins of 

 drying fluids, while Naegeli asserted that a current of considerable 

 force is necessary to effect such transportation, and that the lifting 

 up of the particles into the air by the current was greatly influenced 

 by the force of adhesion which exists between the particles and 

 the surface to which they adhere. 



The great media for the diffusion of pathogenic microbes over 

 the surface of the globe are the air and water. Some of the micro- 

 organisms, as the pus-microbes, appear to be almost omnipresent, 

 while others are diffused over a more limited area, their existence 

 being dependent upon certain conditions of the soil or temperature. 

 Water as a medium of diffusion and vehicle for the entrance into 

 the organism of pathogenic microbes, is of greater interest to the 

 physician than the surgeon. The superficial layer of the soil con- 

 tains most of the disease germs and spores, as they are deposited 

 upon it from the air, and carried into it by water which contains 

 them, the soil in the latter instance serving the purpose of a filter- 

 ing substance. To the surgeon, direct infection with microbes of 

 the soil has awakened new interest by Nicolaier's discovery that 

 the bacillus of tetanus has here its natural habitat, and from the 

 well-known circumstance that the bacillus of anthrax is known to 

 multiply in the soil of pastures which have been inhabited by 

 animals suffering from this disease. 



