,'r 



75 

 TABLE XXXVIII. (continued) 



the farther away the source was from cultivation, the smaller was the 

 proportion of positive results, but that they were never altogether absent. 

 Unfortunately, neither Houston nor Konrich differentiated between the aero- 

 genes and coli sections. 



Johnson and Levine first pointed out that the coli-like microorganisms 

 of the soil were strikingly similar to those obtained by Rogers and his as- 

 sociates from grains and that they were quite distinct from the true Bact. 

 coli of feces. 



The observations of Johnson and Levine are based upon 42 samples 

 of soil obtained from experimental plots, (data on treatment of which is 

 available for many years) from orchards, corn fields, and miscellaneous 

 sources in different parts of the state of Iowa. 



The method of isolation of cultures was by planting on litmus lactose 

 agar directly or after preliminary enrichment in lactose broth, incubation 



