46 FIELD CROPS 



and heat; how they utilize these different factors, and the results if 

 any are lacking. Farmers' Bulletin 408, School Lessons in Plant 

 Production, may be obtained free by any teacher and will be very help- 

 ful in suggesting useful exercises for the laboratory. The first four 

 chapters of A. D. Hall's recent book, "The Feeding of Crops and 

 Stock," will be found very readable and instructive, as well as sug- 

 gestive of numerous methods of illustrating the germination of seeds 

 and the growth of plants. 



SUPPLEMENTARY READING 



Farmers' Bulletin 408, School Exercises in Plant Production. 

 Bailey's Cyclopedia of American Agriculture, Vol. II, pp. 5-21. 

 Hall's Feeding of Crops and Stock, pp. 1-77. 

 Johnson's How Plants Grow. 

 Johnson's How Plants Feed. 



