TRANSFORMATION OF MINERALS IN THE SOIL 



647 



Kamamura 11 described an organism, Volcanothrix silicophila, found 

 in the volcanic material in Japan at an altitude of 6600 feet, which 

 formed a zoogloeal mass, the ash of which contained 8.873 per cent 

 silica. 



2.0 _ 



a 



3 



a 3.0 



4.0 



5.0 



6.0 



log Ch 5.0 



4.0 



3.0 



2.0 



Fig. 48. Influence of sulfuric acid upon the solubility of calcium silicate (from 

 Wright). 



The presence of bacteria was also found to increase the etching 

 power of the roots of plants. 12 

 A certain relationship exists between the hydrogen-ions produced by 



11 Kamamura (cited by Wright, 1922 (p. 648)). 



12 Fred, E. B., and Haas, A. R. C. The etching of marble by roots in the pres- 

 ence of bacteria. Jour. Gen. Physiol., 1: 631-638. 1919. 



