2i0 MASS. EXPERIMENT STATION BULLETIN 271 



DEPARTMENT OF BACTERIOLOGY AND PHYSIOLOGY 

 G. E. Gage in Charge 



Nitrogen-Fixation in Relation to Leguminous Crops. (James E. Fuller"). 

 Previous work on phases of this subject has been reported during the past 

 year in Soil Science, Volume 30, July, 1930, under title of "Nitrogen-Fixa- 

 tioii in Field Soil under Different Conditions of Cropping and Soil Treat- 

 ment." During the course of this investigation the data indicated the 

 possibility that the lime applied may have been responsible for the varia- 

 tions in the amount of nitrogen fixed by the soil from the different plots 

 ot the field. Tlie hydrogen-ion concentration of the soil from the various 

 plots showed no marked variation, although the quantity of linie applied 

 varied widely. Therefore, there is a possibility that lime may have some 

 relation to Azotobacter metabolism other than the neutralization of acid- 

 ity. 



Synthetic media have been studied in the laboratory during the year 

 to ascertain the influence of different calcium compounds on the amount 

 of nitrogen fixed by the different strains of Azotobacter. These experi- 

 ments are being repeated. Plant-house experiments are being conducted in 

 which soil is treated with the calcium compounds employed in the synthetic 

 media, these compounds including salts varying in their ability to neutral- 

 ize acids. The purjiose of the investigation is to study the influence of 

 tiie calcium in the presence and absence of combined nitrogen. 



Another phase of this project has had to do with distribution of cellu- 

 lose-decomposing activity in the soil of the experimental field. The data 

 at present appear to correlate the nitrogen-fixing activity of the soil from 

 the different plots of the field. 



Besides work on this project, a cooperative experiment has been in pro- 

 gress with the Department of Botany. This has had to do with the effect 

 of temperature on the utilization of nitrates by cellulose-decomposing or- 

 ganisms. The data obtained thus far indicate that from the laboratory 

 standpoint soil known to contain active cellulose-decomposing organisms 

 will bring about decomposition of cellulose within a certain space of time. 

 Decomposition was less active at temperatures below 1.5° C. Data from the 

 pot experiments will be found in the report of the Department of Botany. 

 Laboratory Service. (Ralph L. France). During the past year the 

 Laboratorv Service has given assistance to local milk inspectors and milk 

 dealers throughout the Connecticut Valley. Towns and a few cities have 

 called vipon the laboratory for monthly tests of all milk sold within their 

 boundaries. This jihase of service has grown into a health control service 

 not only through the medium of laboratory tests but also through in- 

 formation given in personal interviews with dealers and inspectors and by 

 inspections of dairy barns. 



Samples of water from private supplies from many parts of the State 

 have been submitted for bacteriological analysis to establish their purity 

 for drinking purposes. Fifty per cent of all the samples analyzed during 

 the year were unsafe for hunum consumption. This condition shows no 

 great improvement over previous years, and indicates that there is need 

 for active education concerning the location and construction of rural 



