Lecture 1 — 25 — Survey 



Stewart, Guy R. Effect of season and crop growth in modify- 

 ing the soil extract. Journal of Agricultural Research 12: 

 311-368, 1918. 



Thomas, Moyer D. and Hill, George R. The continuous meas- 

 urement of photosynthesis, respiration and transpiration 

 of alfalfa and wheat growing under field conditions. Plant 

 Physiology 12: 285-307, 1937. 



