388 E. P. Dearrick 
the manganese content of the leaves. Woods (1899) states: “It has 
long been known that chlorophyll could be readily converted by oxida- 
tion, into a yellow coloring matter, xanthophyll.”’ While a moderate 
stimulation of the oxidizing power of the plant juices may result bene- 
ficially, an excessive stimulation may result in the oxidation of the chloro- 
phyll. 
Relation of manganese to the oxidizing power of soils 
In some eases the lack of fertility in a soil has been shown to be due to 
the presence of certain organic substances injurious to plant growth. 
Schreiner and Shorey (1909) found that when such soils are well aérated 
they become productive. Schreiner, Sullivan, and Reid (1910:44) state 
that the addition of manganese to soils promotes “ the most active oxi- 
dation,” and ‘ by its strong oxidizing power ..... would render the 
injurious material in the soil harmless or even beneficial and by the oxi- 
dation of inert or rather stable organic matter might cause”’ a liberation 
of plant food. A brief study of the effect of manganese salts on the oxi- 
dizing power of soils has therefore been made by the writer. 
Portions of Dunkirk silt loam were sprayed with solutions of manganese 
chloride, manganese sulfate, potassium permanganate and suspensions of 
manganese carbonate, and manganese dioxide, in quantities such that 
the manganese added was in the proportion of 10, 100, and 1000 parts 
of manganese per million of dry soil. It was thought that by spraying 
the soil a more uniform distribution of the manganese could be obtained. 
Consequently the calculated amounts of the salts were added to sufficient 
water to bring the soil to 25 per cent moisture content (dry basis). The 
spraying was done with a simple atomizer, made with two pieces of glass 
tubing of different bore and a wide-mouth bottle. It was found that the 
physical condition of the soil was very good when the water was added 
in this way. A determination showed that the moisture lost in the form 
of mist and evaporation during the treatment was negligible. The soils 
were stored in glass quart jars for about seven months. 
To test the oxidation in the soil, 50 cubic centimeters of the following 
solution was added to 10 grams of the air-dried soil in a centrifuge tube: 
10 grams aloin 
200 cubic centimeters N/10 HCL 
790 cubic centimeters distilled water 
