LETTER OF TRANSMITTAL 
Honolulu, Hawaii, May 1, 1912. 
Sir: I have the honor to submit herewith and recommend for 
publication, as Bulletin Xo. 28 of the Hawaii Agricultural Experi- 
ment Station, a paper on the Effect of Manganese on Pineapple 
Plants, and the Ripening of Pineapple Fruit, prepared jointly by 
myself and Mr. W. P. Kelley, chemist. Chemical investigation on 
the cause of yellowing of pineapples on certain soils and on the 
ripening of the pineapple fruits has been carried on for the past 
three years, and some of the important results of this investigation 
are stated in this paper. A microscopic study was made of all the 
different parts of pineapples for the purpose of learning the struc- 
tural changes produced by the presence of large quantities of man- 
ganese in the soil and the morphological changes which occur in the 
ripening of the fruit. The anatomical and chemical findings are in 
rather striking harmony. The practical bearing of these investiga- 
tions should be of importance in the further development of the 
pineapple industry. 
Respectfully, E. V. Wilcox, 
Special Agent in Charge. 
Dr. A. C. True, 
Director Office of Experiment Stations, 
V. S. Department of Agriculture, 'Washington, D. C. 
Publication recommended. 
A. C. True, Director. 
Publication authorized. 
Ja^ies "Wilson, Secretary of Agriculture. 
(3) 
[Bull. 28] 
