51 



lillle or no toxic effect. In all cases the beneficial effect 

 was intensified, or the toxic effect entirely eliminated 

 when the i)ots were allowed to stand for a period of 

 about six months after the application of the com- 

 pounds. 



Upson and Powell (30) report that vanillin in the soil, 

 even at a concentration of 1000 parts per million, shows 

 veiy little harmful effect on the growth of wheat. 

 Cumarin acted (piite differently in the soil from what 

 it did in water culture. 



EXPERIMENTAL 



Soils Used 



The soils used were a Norfolk sandy loam from what 

 is known as the "Culler's rotation plot" and a sandy 

 loam from plots on the Experiment Station Farm 

 which have received annual applications of ammonium 

 sulfate. The former soil was ])ractically neutral in 

 reaction, and is of fair fertility. The latter was decid- 

 edly acid. Clover grows poorly upon it. The first soil 

 is similar to one used by Funchess in which the results 

 noted above were obtained. 



Chemicals Used 



The vanillin, cumarin, pyridine and quinoline were 

 Merck's C. P. chemicals. 



The Effect of Vanillin, Cumarin, Pyridine and Quino- 

 line ON the Microorganisms of the Soil 



Nine kilograms of air diy soil (Norfolk sandy loam) 

 were placed in two gallon pots. The pots were thor- 

 oughly watered with tap water and allowed to stand 

 for thirty days. At the end of that time the soil was 

 removed from the pots and spread on sterile paper. 

 The compounds were added, thoroughly mixed with 

 the soil l3y means of a sterile spatula and the soil 

 repotted. The vanillin and cumarin were added at 

 the rate of 9 gms. per pot; the pyridine and quinoline 

 at the rate of 14 cc. per pot. Each treatment was made 

 in duplicate. The soil in two i)ots was removed, mixed 

 and repotted without treatment. These two pots served 

 as checks. An attempt was made to keep the water 

 content uniform throughout the series by weighing 

 about once a week and making up the loss with di- 

 stilled water. The number of microorganisms devcl- 



