THE EFFECT OF PREVIOUS VEGETATION 345 



lutions containing nutrient salts. An experiment was also made 

 by dissolving the oily material as far as possible, in distilled 

 water and using the water as a culture. In the water cultures 

 the oily substance was also hannful to cabbage plants. The ef- 

 fect of the substance separated from the sesame soil on wheat seed- 

 lings in nutrient solutions and water cultures was only slightly 

 harmful. The plants in the cultures containing the oily matter 

 did not make quite as large a growth as the control cultures, 

 yet it was not nearly so harmful to wheat as to cabbage plants. 

 The green weight of the plants after three weeks growth is given 

 in the table. The green weights represent two cultures, each 

 containig ten plants. The relative decreased growth is also 

 given. 



TABLE I 



Showing the effect of oily material isolated f rom sesame soil, on the growth of cabbage 



and wheat plants 





CABBAGE 



WHEAT 



Gr. Wt. 



Relative 



Gr. Wt. 



Relative 



Nutrient solution 



3.36 



100 



4.50 



100 



Nutrient solution and oily substance 



2.80 



83 



4.30 



96 



Distilled Water 



2.00 



100 



2.42 



100 



Distilled Water and oily substance 



1.75 



88 



2.35 



97 



From the table it is readily seen that the oily substance was 

 quite harmful to the cabbage seedlings. In the nutrient solu- 

 tions the growth was reduced from 100 to 83 and in distilled 

 water from 100 to 88. The plate shows the cabbage plants growing 

 in nutrient solution in the early stage of the experiments. Nos. 1 

 and 2 are the nutrient solutions and Nos. 3 and 4 are nutrient 

 solutions plus the oily material. As shown in the table the wheat 

 plants were only slightly affected by the oily substance isolated 

 from the sesame soil. In nutrient solutions the growth was re- 

 duced from 100 to 96 and in distilled water from 100 to 97. 



From the foregoing it appears that the soil, which had grown 

 sesame contained constituents which were harmful to cabbage 

 plants, but did not materially affect wheat seedlings. The field 



