io6 



THE SPIRIT OF THE SOIL 



series of trials were made. Nine pots in all were 

 taken, and 15 grains of wheat were planted in each 

 in sand. All nine pots received Ammonia, Phos- 

 phate, and Potash, as in the previous experiment. 

 The first series had this alone, the second series also 

 received some 17 per 1,000,000 solution of the 

 Phosphotungstic acid extract, while the third was 

 given some of the 0*35 per 1,000,000 solution of the 

 Silver nitrate extract. As before, the plants were 

 first treated a week after planting, and then each pot 

 received 100 c.c. of its food solution once a week. 

 At the end of the seventh week the results after 

 drying were as follow : 



As this experiment showed that the silver nitrate 

 extract gave results comparable with those obtained 

 with the Phosphotungstic acid precipitate, it was 

 decided further to try the experiment of growing 

 wheat seedlings in water culture. Two sets of 

 eighteen similar seedlings were selected, each set 

 being originally of equal weight 473 grammes. 



