Hf 



VITA. 



The writer was born at Dagus Lines, .-Pennsyl- 

 vania, May 3, 1883. In 1906 he received the degree of 

 Bachelor of Arts from Cornell University. Prom August 

 ly06 to September 1907 he was assistant chemist in the 

 Agricultural Experiment Station, Tucson, Arizona. 

 From 1907 to 1912 he was scientist in the Bureau of 

 Soils, United States Department of Agriculture. Prom 

 1912 to 1914 he was in private practice as a chemical 

 engineer in San Francisco, California. Since October 

 1914 he lias been a student in the Department of Plant 

 Physiology of the Johns Hopkins University. 



