102 



L. T. SHARP 



writing in 1877 compares the lower microscopic forms of life 

 with the seeds of plants, stating that drying does not destroy 

 their vitality, but that they may endure in the desiccated con- 

 dition for hundreds or even thousands of years. Schroder^ deter- 

 mined that barley grains desiccated over sulphuric acid main- 

 tained their germination power for eleven to twelve weeks, mold 

 spores were alive after seventeen months, yeast cells lived from 

 seventeen weeks to seven months, and putrefactive bacteria 

 resisted the drying effects of the acid for twenty-one to twenty- 

 five weeks. Algae were aUve after five years of drying under 

 room conditions. 



By experimentation with two separate portions of the same 

 soil, one air-dried for two months, the other for two years, Rahn' 

 determined that the soils contained respectively but one-third 

 and one-fifth of the original number of bacteria. Though a 

 decrease in total number was observed, the rate of CO2 and 

 acid production and ammonia formation from peptone and urea 

 solutions was more rapid when the solutions were inoculated 

 with soils previously air-dried than when inoculated with moist 

 soils. In explanation of the above mentioned phenomenon noted 

 by Rahn, Russel^ and Hutchinson suggest that the drying of 

 soils diminishes to a large extent the number of protozoa, which 

 had been feeding on bacteria, and this elimination of competition 

 enables the bacterial processes to gain superiority when sterile 

 solutions are inoculated with dry soil. 



Referring to the resistant power toward drying possessed by 

 species of the Azotobacter group, Lohnis^ states that they are 

 comparatively less sensitive than other groups of organisms, and 

 that some of the cells remain ahve for months or even years. 

 However, Lohriis^ and Pillai observed that nitrogen fixation was 

 somewhat less in dry years than in wet years, and from^ experi- 



^ Untersuch. aus dem. Bot. Inst, zu Tubingen 2: 11, 24-25, 34, 38 and 41. 1886- 



5 Centlb. f. Bakt. 20: 42, 56. 1907-08. ^ 



^ Jour, of Agri. Science, p. 119. 1909. 



' Einfuhrung in die Bakteriologie, p. 687. 



s Centblt. f. Bakt. 20: p. 794. 1908. 



• Einfuhrung in die Bakteriologie, p. 688. 



