Concentration of Solutes in Vacuolar and Cytoplasmic Saps

Water Relations of Plant Cells. Ii

“…XXII and XXIV. The most remarkable contrast between our results and those of Phillis & Mason (1937) is that, whereas they obtained no exudation of juice from living cotton leaves when pressures as high as 280 atm. were applied, we find marked exudation from beech leaves at applied pressures of 20-30 atm.…”

“…The choice of a non-living model consisting of a solution separated from the water phase by an ideal semipermeable membrane as a representation of the living vacuolated cell seems to us, in view of the evidence brought forward in this paper and in a number of other recent investigations (Bennet-Clark et al 1936;Buhmann, 1935;Mason & Phillis, 1939;Phillis & Mason, 1937;Roberts & Styles, 1939), to be unjustified. There seems to be little doubt that the hydrostatic pressure inside a fully turgid cell is often much in excess of the osmotic pressure of the vacuolar sap; moreover, many of the solutes which on the classic theory are supposed to be responsible for the static osmotic pressure are undoubtedly able to permeate the protoplast (cf.…”

Plant Juices in Relation to Silage Fermentation

“…It is generally assumed that the expressed juice comes mainly from the vacuoles and that the variation in solute concentration is due to a differential filtering action of cell membranes. On the other hand, Phillis and Mason (8) found that with fresh cotton leaves the concentration of the inorganic constituents in the juice did not change as the pressure increased, provided no 'shearing forces' were present. They found that the yield of sap under these conditions, even at pressures as high as 16,000 Ib/in^., was very limited.…”

Methods of Sap Expression From Plant Tissues With Special Reference to Studies on Salt Accumulation by Excised Barley Roots

“…The values for the fresh samples are discontinuous at the limit of hydraulic pressure and are joined by dotted lines to values obtained on the frozen and re-expressed press-cakes. The approximately constant values for the different fractions of sap from frozen tissue up to a removal of 90 per cent of the total liquid present indicate that the expressed liquid was representative of the tissue as a whole, associated with the destruction of the normal state of the living substance (Lepeschkin, 1936;Mason and Phillis, 1936;Phillis and Mason, 1937). Freezing, like heat killing, cytolysis, and thorough grinding, apart from other possible objections, has made possible the release of the tissue fluids in a composite mixture.…”

“…As with initially frozen tissues, the liquid so obtained is of relatively constant composition. I f any fraction of this liquid, or a composite sample, is analyzed, it is generally found that its solute concentration is higher than that of any fraction, or composite sample, of the freshly pressed tissue (Gortncr, Lawrence and Harris, 1916;Phillis and Mason, 1937) although this relation may not hold for all types of plant tissues. Evidence at hand shows that discs of potato tuber after accumulating potassium salt may have an electrolvte concentration in the fluid from the residual fro;en press-cake even lower than that of the fluid expressed from fresh tissue.…”