124 ABSTRACTS 



form. This cannot be the only factor, however, for the longevity of 

 bacteria in various soils is not proportional to the grain-size and hygro- 

 scopic moisture. 



Recently Van Suchtelen has succeeded in extracting the soil-solu- 

 tion directly from soil. It was found in the course of the present experi- 

 ments that if bacteria are suspended in the solution extracted by Van 

 Suchtelen's method from a rich clay loam and are then mixed with 

 sand and dried, they live longer than if suspended in physiological salt 

 solution and then dried under similar conditions. This suggests that 

 the reason why bacteria resist drying longer in a rich clay loam than 

 in sand is not only because of the greater amount of hygroscopic mois- 

 ture present but because there is something present in the soil-solution 

 of the loam that has a protective influence upon the bacteria. The 

 soil-solution was found by Van Suchtelen to contain a slimy material; 

 and the writers suggest that this might be the substance protecting the 

 bacteria when dried. — H. J. C. 



A Comparison of the Acid Production of the B. coli Group Isolated from 

 Various Sources. W. W. Browne (Amer. Jour, of Public Health, 

 1916, 6, 39-48). 



The author undertook this study to determine the amount of acid 

 production in various carbohydrate solutions by members of the B. 

 coli group, as a guide to the recentness or remoteness of pollution of 

 oysters in Narragansett Bay. He found that members of this group 

 isolated from either feces or oysters produced their maximum amount 

 of acid in lactose and glucose when incubated at 37°C. for 24 hours; 

 furthermore that the maximum amount of acid was produced by the 

 end of 24 hours. One series of experiments showed that the largest 

 amount of acid was produced in the monosaccharides and hexites 

 (glucose, levulose, galactose, arabinose, xylose, isodulcite, mannite), 

 less in the disaccharides (lactose, maltose) , and least in the trisaccharide 

 (raffinose). That is to say the yield of acid varies inversely as the 

 complexity of the sugar. The author concludes that the members of the 

 B. coli group isolated from feces produce more acid in carbohydrate 

 solutions than cultures isolated from oysters, the average differences 

 being very slight, but apparently consistent in all the different fer- 

 mentable media studied. — D. G. 



Relation Between Certain Bacterial Activities in Soils and Their Crop- 

 Producing Power. Percy Edgar Browne. Journal of Agricultural 

 Research 1916, 5, 855-869. 



These experiments as a whole represent a line of investigation in 

 soil bacteriology which it is believed will ultimately place the subject 

 on a more practical basis — a basis which will permit the direct appli- 

 cation of the results obtained to the solution of soil-fertility problems. 

 The relations between the bacterial activities studied and the actual 

 crop yields on these plots have proved so striking and so consistent 

 that it was felt that accidental coincidence had been practically elimi- 



