Sui\i\al ot Piithoiicns in the Soil 285 



'ti 



Clostiicliuni tcUiiti appears to be also uiiivt'isalK tlistrihulcd in 

 soils fertilized with animal manures and' subject to the dust of the 

 streets. Nicolaier demonstrated the presence of this organism in 

 more than 50 per cent of the soils examined, an observation later 

 confirmed by others. Of 100 Scottish soils examined, 4 gave cultures 

 producing botulinus toxin and 5 tetanus toxin. It was even sug- 

 gested that the tetanus organism develops in rotting straw or manure, 

 taking a part in processes of decomposition. The presence of this 

 organism in the soil has also been ascribed to fecal excretions, be- 

 cause of its de\'elopment in the intestine. 



The subject of the gas-gangrene-producing bacteria has received 

 special consideration in connection with the study of war wounds 

 and trench fever. Spores of CI. sporogencs, Cl. welchii, CI. teiiius, 

 CI. ocdemoticns, Cl. bifermentans, Cl. cochleariits, Cl. tetani, and of 

 other bacteria haxe been found in all soils of Central Europe. 



The nature of the soil, or its physical, chemical, and biological 

 conditions, have a marked influence upon the survival of these or- 

 ganisms in the soil. The bacterimn causing fowl typhoid {Shigella 

 gallinorinn) will not remain in the soil for more than a week at a 

 reaction of pH 6.2-6.4 or lower. At a pH of 6.7-7.0, however, the 

 organism does not seem to be affected and will survive in the soil 

 for 40-70 days. The organism causing white diarrhoea in chickens 

 (Sh. pullorum) shows somewhat greater susceptibility to acid soils 

 than Sh. gallinarum; it survived for more than 64 days in soils of pH 

 7.0. In moist soils, the organism was more viable and less sus- 

 ceptible to lower pH than in dry soils; it survived for 8 days in soils 

 of pH 6.2-7.0. Mycobacterium tuberculosis will survive in the soil 

 for many years, without losing its virulence. 



The causative agents of human and animal actinomycotic diseases 

 are often claimed to be brought about by soil organisms or forms 

 harbored upon plants. Klinger drew attention to the fact that none 

 of the aerobic actinomycetes commonly found on grasses and in 

 straw infusion (also in soil) were isolated by him in any actinomy- 

 cotic case. Only anaerobic forms were obtained from the latter; 

 these developed on most media at temperatures above 30° C, and 

 only seldom were cultures obtained which made a scant growth 

 under aerobic conditions. Mixed infections consisting of anaerobes 

 growing at body temperature together with aerobes are often ob- 

 tained. We have to do here with species which have adapted them- 

 selves to a svmbiosis with warm-blooded animals, and which have 

 almost nothing in common with aerobic saprophytes. There is no 



