126 



liariiiful eft'ect in the soil on the growth of wheat. 



From the above brief review it can be noted that 

 Davidson, Fraps and Upson and Powell found little 

 harmful effect from the addition of vanillin to the soil. 

 Skinner also found vanillin to have little or no effect 

 when added to the fertile Hagerstown loam. He obtain- 

 ed, however, marked bad effects in the Arlington soil, 

 in the infertile Florida sandy loam and in the infertile 

 Susquehanna sandy loam. 



From our own work on Alabama soil we assume that 

 the results first cited where little harmful effect was 

 observed were due to the fact that bacteria which fed 

 on vanillin were present and the soil conditions were 

 suitable for their growth and their destructive action 

 on vanillin. On the addition of vanillin to these soils 

 the bacteria destroyed the vanillin and little or no bad 

 efl'ect resulted. The results in the Arlington soil, in 

 the Florida sandy loam and the Susquehanna sandy 

 loam would be explained as due either to the absence 

 of suitable bacteria or to conditions in those soils which 

 prevented the growth and the action on vanillin of the 

 bacteria. Under either of these conditions the added 

 vanillin would persist and evidence its toxicity. To 

 demonstrate the correctness of this view samples of all 

 the above soils except the Hagerstown loam, Florida 

 sand}' loam and Susquehanna sandy loam have been 

 examined for the presence of vanillin-destroying bac- 

 teria. In addition the effect of vanillin on the numbers 

 of microorganisms in the Arlington soil has been 

 studied. 



Through the courtesy of Dr. T. L. Lyon of the New 

 York State College of Agriculture a sample of soil was 

 received from the same field and as nearly as could be 

 determined from the same spot as that used by David- 

 son in the experiments noted above. This soil was col- 

 lected with a sterile spoon and shipped by express in a 

 sterile can. Upon its receipt, using all precautions to 

 avoid contamination, a small quantity was added to a 

 sterile nutrient solution containing vanillin." 



'This solution contained: 

 Na NO3 0.1 gm. 



K, HPO4 0.1 



Mg SO4 0.05 



NHv CI 0.1 



KCr 0.05 



Vanillin 0.1 



Water Dist. 200 cc. 



