44 BOARD OF AGRICULTUEE. [Jan., 



sources of animal nutrition and animal power and animal product. 

 "We would know the effects of changes introduced by man upon 

 the reaction of the animal with his food, and much more. 



Let us illustrate with the corn plant. What does the agricutu- 

 ral experimenter want to know ? He requires the aid of the 

 investigator to determine: 



The Investigator. 



1. Plant-food. 



1. Character of plant-food. 



2. Sources of plant-food, and causes which determine its availa- 



bility. 



3. Effects of special plant foods in excess upon growth and com- 



position of product. 



4. Effect of deficiency of supply of certain plant-foods. 



5. Essential and non-essential plant-foods, in their various rela- 



tions to plant products. 



2. The Soil. 



6. Physical relations of the soil to plant-food and plant-feeding. 



7. Chemical relations of tlje soil to plant-food and plant-feeding. 



8. Changes produced in the plant by its relation with physical 



and chemical soil conditions. 



3. The Plant. 



9. The plant, as modified by heredity. 



10. How the plant feeds, and how it grows. ' 



11. Germination, and the conditions which are involved. 



12. Growth, and its conditions. 



13. Development, and its conditions. 



14. When the plant establishes its relations with the food supply 



of the soil, and when these relations are discontinued. 



15. Changes produced in the plant by its atmospheric relations. 



16. Changes produced in the plant by its soil relations. 



17. Changes produced in the plant by the acts of man, including 



selection, protection, tillage, fertilization, etc., and the con- 

 ditions involved. 



4. The Man. 



18. Selection, its influence in modifying products. 



19. Protection, or the warding off of injurious competitors, in- 



cluding distance of planting, weeding, etc., and its influence 

 on the plant growth and cropping. 



