284 DISTRIBUTION OF BACTERIA 



have their home in the soil, such as the B. tetani and B. 

 feseri (symptomatic anthrax). A great many more disease- 

 producing bacteria simply pass a short but variable time in 

 the soil, in an inactive condition. There has been a great deal 

 of discussion as to whether or not pathogenic bacteria can 

 grow in the soil, and it is still an open question how long these 

 bacteria can persist in the soil if they do not grow. There is, 

 perhaps, no good reason a priori why disease-producing bac- 

 teria might not grow in the soil. In certain localities, at least, 

 there would be an abundance of food, and at certain seasons of 

 the year there is sufficient heat. Some pathogenic forms will 

 grow in media made from soil extract, but the evidence that 

 bacteria can grow in the natural soil is very slight, and the 

 chief reason why they do not grow, it is easy to imagine, is 

 because of the antagonism of what may be termed the soil bac- 

 teria. Disease bacteria are preserved in the soil for a con- 

 siderable period of time, and this is especially true of those 

 bacteria which have spores. Soil which has become contami- 

 nated with the Bact. anthracis is dangerous soil for many 

 years. The sporeless forms live for a much shorter time, and 

 ordinarily they cannot cope with the unfavorable conditions 

 which surround them except for a brief time. The practical 

 importance of this problem comes out in the question of the 

 persistence of disease bacteria in human or animal cadavers. 

 The popular notion is that a cemetery is a dangerous place 

 and many epidemics have been traced, in the popular mind, 

 to close proximity to such places, or to contamination of 



