12 
acid. The presence of citric acid in pineapples would tend to keep 
the manganese in solution, and this may explain the fact that no 
visible deposits of manganese could be found in pineapples. 
In addition to the brown color of the protoplasm referred to above, 
it should be mentioned that the roots of pineapples growing on 
highly manganiferous soils show a darker brown color than in normal 
plants and that distinct brown patches appear on the upper surface 
of the leaves of plants during the later' stages of yellowing. These 
brown areas may be sunken or elevated and the roughness of the 
surface seems to be due to the death of the tissue underneath and the 
consequent shrinking, thus throwing the surface into folds. The 
brown patches are perhaps the results of sun scald, which apparently 
takes place more rapidly after the living tissues have been injured by 
manganese and the regulatory apparatus is thereby destroyed. 
THE CHEMISTRY OF THE PINEAPPLE PLANT. 
The development of a yellow color in the leaves of pineapples on 
certain soils of Oahu has become a matter of common observation. 
Investigations into the cause of this phenomenon have resulted in 
establishing a direct relationship between the occurrence of manga- 
nese in the soil and the yellowing of the pineapples. In 1909, 1 
from a preliminary investigation, it was pointed out that the degree 
of yellowing is directly proportional to the amount of manganese in 
the soil, and that the manganese exists in the soil in a state of higher 
oxids, from which forms it readily becomes available to the roots 
of plants. It was further shown by the use of the Dyer method that 
the manganese is quite soluble. Subsequently it has been pointed 
out that the solubility of manganese in various dilute organic acids 2 
is very pronounced, and that its solubility in distilled water in some 
instances is greater than that of any other element in the soil. It 
was further pointed out that the general metabolism of the pineapple, 
when grown on manganiferous soils, is considerably modified. In 
order to throw more light on this question, an extensive study of the 
chemistry of the pineapple plant has been undertaken in conjunction 
with the anatomical and physiological investigations. 
The results obtained, it is believed, will enable a proper under- 
standing of certain peculiarities already mentioned and afford a 
more exact chemical basis for a comprehension' of the physiology of 
the plant, and also furnish some explanation for the peculiarities 
attending the presence of large amounts of manganese in the soil. 
In this study the mineral constituents of the several parts of the 
plant have been determined. 
1 Hawaii Sta. Press Bui. 23; Jour. Indus, and Engin. Chem., 1 (1909), pp. 533-538. 
2 Hawaii Sta. Rpt. 1909, p. 63. 
[Bull. 28] 
