A System of Analysis for Plant Tissue by Use of Plant Juice.

The utilization of expressed plant juice for determining the chemical constituents of a plant is becoming increasingly important. It has the advantage of presenting the products of metabolism in a state more similar to that found in living tissue than any of the more commonly used extraction methods. Conditions of state and equilibrium, however, can probably never be identical for juice within and without the cell, for at the moment of cell rupture, the coniditions that control living cellular activity are changed. To illustrate, if living leaf tissue is placed in an atmosphere of carbon dioxide, the juice becomes more basic (8), but if the cell liquid is expressed, and carbon dioxide bubbled through it, the juice becomes more acid. The first important studies of expressed juice were for the investigation of physical constants such as density, refractive index, freezing point, etc. This .work has been summarized by SASTRI and SREENIVASAYA (21). Recently, attention has been paid to the inorganic and more particularly to the organic fractions, of plant juice including the sugars and nitrogen fractions. This paper is presented to describe methods for the determinations of a portion of the inorganic and organic constituents in plant juice extracts, and calculation of the results on a fresh weight basis.