LETTER OF TRANSMITTAL. 
Hawaii Agricultural Experiment Station, 
Honolulu, Hawaii, September H, 1914- 
Sir : I have the honor to submit herewith and recommend for pub- 
lication as Bulletin No. 39 of the Hawaii Experiment Station a paper 
on The Biochemical Decomposition of Nitrogenous Substances in 
Soils, by W. P. Kelley, chemist. More exact information is needed 
on the sources from which plants draw nitrogen for their growth. 
This bulletin contains the results of a study of the percentages of 
ammonia derived from the bacterial decomposition of various organic 
nitrogenous substances in soils. In six out of the eight substances 
used in this study the basic diamino acid nitrogen was found to be 
more readily converted into ammonia than was the nitrogen of 
other groups. 
Respectfully, 
E. V. Wilcox, 
Special Agent in Charge. 
Dr. A. C. True, 
Director States Relations Service, 
V. S. Department of Agriculture, Washington, D. C. 
Publication recommended. 
A. C. True, Director. 
Publication authorized. 
D. F. Houston, 
Secretary of Agriculture. 
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