271 



9. SUMMARY OF CONCLUSIONS 



Grains of Zea mais may be immersed in kerosene for periods of 

 ten to twenty days without injury if the optimum conditions for the 

 germination and growth of such grains are provided. These condi- 

 tions incUide the removal of the superficial oil from the grains and the 

 presence of a minimum amount of water during germination and in- 

 itial growth. 



Injuries which occur to the dry grains immersed in kerosene for 

 longer periods than above indicated are due to the penetration of the 

 oil into the embryos through imperfect membranes. 



The dry membranes covering the corn embryo, when perfect, are 

 impermeable to kerosene and to Sudan III, 



Some grains of Zea mais may be immersed in kerosene for eight 

 years without injury to the dormant embryo. 



The life of dormant grains, with membranes which have been 

 mechanically injured, is destroyed within seventy-five days after im- 

 mersion in kerosene. 



Kerosene is injurious to the germinating grains in direct propor- 

 tion to the length of time of immersion and to the increase of the; 

 water content of the soil above the minimum required for germina- 

 tion. 



When moist grains are immersed in a solution of kerosene and 

 Sudan III, the membranes are penetrated by the kerosene but not by 

 the Sudan III. The membranes are, therefore, semi-permeable. 



The germinating corn grain may absorb and dispose of a limited 

 amount of kerosene without injury. The smaller the amount of water 

 present during germination the larger the quantity of kerosene which 

 can be disposed of. Older corn seedlings may dispose of compara- 

 tively large quantities of kerosene without injury. 



It is not advisable to treat seed corn with kerosene unless the 

 water content of the soil is under control. 



The injurious effects of petroleum oils on germinating corn seem 

 to vary inversely as the volatility of the respective oils. 



