SOME BACTERIOLOGICAL STUDIES OF OLD SOILS 



L. T. SHARP 

 University of Nevada, Reno, Nevada 



Ficker has published an exhaustive treatise^ in which he dis- 

 cusses the resistant powers of various organisms under widely 

 different conditions of treatment, and classes the spore-forming 

 bacteria, molds, and yeasts, cyst-producing protozoa, ^ and thick- 

 walled cells in general as morphological forms exhibiting high 

 resistant powers. Soils exhibit an extreme complexity of chem- 

 ical and physical conditions, and a great diversity in the number 

 and species of their micro-flora, and therefore offer an unusually 

 good field for the investigation of the resistance of organisms 

 to desiccation, a subject of much practical importance in the 

 arid regions of the world. The significance of desiccation in 

 general bacteriological practise is apparent in the preservation 

 of various articles of food by drying, and in the transfer of dairy 

 starters, yeasts and cultures of Bacillus radicicola on dried media. 

 It is of interest to note that manufacturers guarantee the vitality 

 of their dried cultures for only a few months. It might be 

 expected that drying of short duration would exert no perma- 

 nent injurious effect on soil organisms within the soil, but it 

 would be surprising to find that the long dry spells and intense 

 heat of the arid regions, particularly of the desert areas, did 

 not decrease the number and activity of the different physiologi- 

 cal groups of organisms of economic importance in the soil, and 

 perhaps alter and rearrange their relative abundance. 



Numerous Hving organisms, such as seeds, algae, bacteria, and 

 molds, have been studied in relation to their respective endur- 

 ances under a great vp,riety of adverse circumstances. Nageli,' 



' Citation from Bui. 78, Delaware Exp. Sta. 



^ Citation from Microbiology, p. 75. Blakiston's Sons and Company, 1912. 

 ' Citation from Untersuch. aus dem Hot. Inst, zu Tubingen, 2: 28. 188G. 



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THE PLANT WOR1.U, VOL. 16, NO. 4, APRIL, 1913 



