348 



SOILS. 



capacity of each of the mixtures was determined and the earth 

 in the pots kept at the point of half-saturation generally ad- 

 mitted to be the optimum (best condition) for plant growth. 

 Each pot was sown with ten seeds of white mustard, subse- 

 quently reduced to five plants selected for their vigor. 



The (" galvanized ") vegetation pots were made as nearly 

 as possible of similar proportions in depth and width for each 

 dilution, so as to give opportunity for the proportional develop- 

 ment of the root systems. The photographs show the latter 

 as nearly as practicable in their natural form, restored after 

 washing off the adherent soil It was of course extremely dif- 



FIG. 55. Same, diluted i to 3. 



DEVELOPMENT OF ROOTS OK WHITE MUSTARD IN CLAY SOIL, DILUTED WITH 

 VARIOUS PROPORTIONS OK PURK SAND. 



