177 
organic and inorganic compounds of manganese deposited man- 
ganese dioxide in the epidermis of the leaves. Other investigators, 
particularly in Japan, have shown that manganese salts have a 
toxic effect upon plants other than pineapples when used in large 
amounts. It can be said briefly that the manganese oxides and 
hydroxides which exist in the Wahiawa soils are soluble in 
liydroxy acids including citric acid which is responsible for the 
greater part of the acidity of the pineapple ; that it is possible for 
manganese salts to be taken up and deposited in the plant, and 
that these salts in large amounts would no doubt be toxic to the 
plant. It is doubtful, however, if manganese dioxide would be 
deposited in the pineapple as Molish found to be the case with 
water plants for the reason that the citric acid would immediately 
act upon it liberating carbon dioxide. 
Wherever sugar cane has been planted upon these soils it has 
given much better results than pineapples. There must be some- 
thing essentially different in the nature of the two crops with 
relation to manganese that one should be so markedly affected and 
the other practically unharmed. Since the mineral matter of the 
plant is contained in the ash we may expect to find these differ- 
ences made apparent in the ash. The writer has tabulated below 
some of the mineral matter taken up by the sugar cane and by 
the pineapple : 
As the ash of the pineapple is at least 1.5% of the plant ciud 
the ash of cane is not over .8% it will be seen that the pineapple 
plant takes up more of these ingredients pound for pound than 
does the cane. This is true particularly of the manganese, chlorine 
and lime. The greater solubility of the salts in the pineapple may 
be due to greater acidity or some other cause, but we have evi- 
dence from the ash analysis that more of these elements are taken 
up by the plant than by the sugar cane. There is considerable 
manganese present in some soluble form possibly complex and 
organic, there is considerable chlorine present indicating chlorides 
of the alkalis and alkaline earths, and there is an abundance of 
lime. In fact we have in the plant all the necessary elements for 
the decomposition of hydrochloric acid and the formation of cal- 
sium manganites. 
Manganese dioxide with lime forms several manganites, CaO 
MnO, CaO 2 MnO, and CaO 5 Mn02- These compounds are 
very toxic and we may suppose that they could be formed in the 
plant or in the soil around the roots froni manganese chloride. 
Pineapple 
Sugar Cane 
Manganese Mn.O^ . 
Chlorine 
Lime 
Potash 
Phosphoric acid P^O; 
1.52 
8.25 
7.61 
40.00 
4.5 
.05 
6.07 
5.78 
33.08 
8.05 
