140 THE SPIRIT OF THE SOIL 



" It has been found, however, that when peat is 

 treated with certain micro-organisms a large quantity 

 of soluble humate is obtained, and the peat is ren- 

 dered alkaline. An aqueous extract of this treated 

 peat (i part peat to 200 parts water) will supply all 

 the plant-food necessary for successful water-culture 

 experiments. As no trace of nitrate was found in 

 the culture solutions during the whole course of the 

 experiments, it is evident that the nitrogen need of 

 the plants was supplied by some form of organic 

 nitrogen present in the solution. 



" Water-cultures with tomato seedlings, ger- 

 minated in sterilized sand, showed that the plants 

 failed to grow in raw peat extract, but in treated 

 peat extract the plants grew well, flowered, and 

 produced fruit. Experiments with buckwheat, 

 radish, and barley gave similar results." 



In view of the disappointment with nitrobacterine 

 it seemed unwise to attempt to generalize from the 

 laboratory results, and three years ago the authori- 

 ties at Kew Gardens were asked if they would be 

 willing to conduct experiments with the new 

 material. 



The authorities at Kew consented. It is un- 

 necessary to state that Kew Gardens are ideal for 

 such a purpose, having the facilities necessary for 

 conducting large scale experiments, and the per- 

 sonnel competent to experiment on rigidly scientific 

 lines. There was an additional advantage, however, 

 about Kew. Experiments had already been tried 

 there with nitrobacterine, and had given negative 

 results. Naturally, therefore, the authorities were 

 inclined to be sceptical, and the stringency of the 

 tests to be made was insured. 



