96 ABSTRACTS 



soils possess differing ferrifying powers, and that the process is in part 

 chemical and in part bacterial in nature. A line of investigations is 

 thus opened up which may prove of much interest. Ferrification in 

 soils apparently should be studied further both from the technical and 

 from the practical standpoints. 



Coll-like Organisms of the Soil. B. R. Johnson. 



Forty-two samples of soil were examined for the presence of coli- 

 like bacteria. Eighteen samples were from manured and twenty- 

 four from unmanured areas. It seems from this study that in both 

 manured and unmanured soils, the incidence of coli-like organisms is 

 considerably greater, if a crop is being raised than if the soil is fallow. 



In a preliminary study of 363 cultures as to their reaction with methyl 

 red and the Voges Proskauer test, 261 were found to be alkahne. Of 

 these over 84 per cent reacted positively to the Voges Proskauer test. 

 Of the 219 cultures which gave the Voges and Proskauer reaction, over 



97 per cent were alkaline to methyl red. This striking correlation be- 

 tween the two reactions has been previously pointed out by Levine, who 

 observes that such forms are rarely found in feces, but relatively abun- 

 dant in sewage. Rogers and his co-workers found methyl red alkaline 

 coli to be the prevailing type on grains and seldom present in cow 

 manure. The prevailing coli-like organisms in the soil are apparently 

 of a non fecal type and they may be differentiated from fecal strains by 

 the Voges Proskauer and methyl red reactions. 



The Influence of Soil Solution on the Longevity of Microorganisms Sub- 

 jected to Desiccation. Ward Giltner and Virginia Langworthy. 

 It is already well known that bacteria resist desiccation in soil for a 

 much longer time than in a naked or unprotected condition such as 

 might be offered by the surface of a solid culture medium. It is also 

 known that any porous substance, not in itself antimicrobial, will offer 

 protection to microbes against the deleterious effects of desiccation. 

 There is a question as to just what factors are responsible for the pro- 

 longed life of microbes in the soil. Soil solution, as used in these tests, 

 was extracted by the paraffin oil displacement or pressure method. 

 Tests were made with other solutions, viz., physiological salt, 0.1 per 

 cent agar, gelatin, albumin, gum arable, soluble starch, also nutrient 

 broth and milk using Ps. radicicola and drying in quartz sand after 

 suspension in the different solutions. The results were that: (a) after 

 suspension in normal salt, gum arable, starch or agar solutions drying 

 in sand was rapidly fatal, few or no bacteria being alive after one 

 month, (b) after suspension in gelatin or albumin solution drying was 

 less rapidly fatal, (c) after suspension in milk or bouillon drying in 

 sand was still less rapidly fatal. Suspension in soil solution followed 

 by drying in sand gave in one case better results than with milk and 

 all other solutions used except broth and in another case better than all 

 other solutions except milk and broth. Tests were also made of the 

 longevity of Ps. radicicola dried in quartz sand and in clay loam. 



