248 MASS. EXPERIMENT STATION BULLETIN 271 



suffered markedly from the high amount of lime, stocks were quite tol- 

 erant and did well. 



The Effect of Temperature on the Nitrate Content of the Soil and Plant 

 Growth in the Presence of Decomposing Cellulose. (L. H. Jones and 

 James E. Fuller). One per cent of cellulose in a soil maintained at con- 

 stant temperatures ranging from 7° to 35° C. definitely affected the ni- 

 trate content of the soil. The tomato, because of its upright habit, was 

 employed as an indicator plant. If the soil is one with a high level of 

 fertility, the plants are unaffected by the reduction in nitrates and the 

 differences obtained in plant growth were directly the result of temperature, 

 a marked increase in growth occurring at a temperature of 22° C. and 

 above. However, if the soil had a low level of fertility, temperature ceased 

 to affect plant growth and the response of the plant M'as dependent upon 

 the available nitrogen. The presence of decomposing cellulose in such a 

 soil reduced the dry weight of the plants as much as one-half to two-thirds 

 of the weight of plants grown in a soil to which no cellulose had been 

 added. With a soil rich in nitrogen the addition of cellulose caused a con- 

 siderable depletion of nitrates at the lower temperatures, while at higher 

 temperatures nitrification was sufficiently active to replace the nitrate used 

 by the cellulose decomposing organisms. In a poor soil to which a con- 

 siderable amount of cellulose was added the ratio of nitrate to cellulose 

 appears to have been so small that temperature had little influence on the 

 degree of nitrate depletion, the rate of nitrification, or the response of 

 the indicator plant. 



Temperature Control Tanks. (A. Vincent Osmun and L. H. Jones). 

 Many changes and improvements have been made in the apparatus for 

 maintaining constant soil temperatures. Better results are now obtained 

 with less attention and lower maintenance cost. In conducting an experi- 

 ment of three month.s' duration no adjustments were necessary except the 

 replacement of a loose nut on one of the contactors. Each of the thir- 

 teen compartments maintained its temperature throughout the period. 

 This apparatus is available for many types of research. It has been of 

 invaluable assistance in the study of the following problems: the smut 

 disease of onions, black root-rot and brown root-rot of tobacco, nematode 

 galls, growth of gladiolus in the greenhoiise, soil temperattire in plant 

 containers, Verticillium wilt of eggplant. 



j\n Electric Steam Generator for Sterilizer Retorts. (Howard Bidwell 

 and L. H. Jones). This steam generator was developed to fulfill the re- 

 quirements of obtaining a sterilizing pressure quickly, and is a decided de- 

 parture from the usual type. About 80 per cent of the water volume in 

 the boiler is available for supplying steam to the sterilizing chamber, with- 

 out danger of low water, or requiring intake of additional water during 

 the sterilizing process. The principle on which this generator operates 

 is original and eliminates the usual delay in obtaining the required steril- 

 izing pressure. The generator is under automatic control at all times, thus 

 reducing necessary attention to a minimum. The details of its construc- 

 tion and operation are given in a paper entitled "Packed heat from a 

 new type electric steam generator" accepted for publication in Industrial 

 and Encjineering Chemistry. 



