The Action of Salts and Non-Electrolytes upon Buffer Solutions and Amphoteric Electrolytes and the Relation of these Effects to the Permeability of the Cell

EFFECTS OF IRON ON THE GROWTH AND ASH CONSTITUENTS OF ANANAS COMOSUS (L.) MERR

“…The results generally emphasize the fact that the absorption of calcium by A. comosus was greatly accelerated by nitrate ions and retarded by ammonium ions, while the extra amounts of iron in the F cultures increased calcium absorption only slightly over those of the 0 cultures. The data suggest that the acceleration of calcium absorption by nitrate ions and its retardation by ammonium ions could have been caused by electrostatic forces as postulated in the theory of GIRARD (7) and HAYNES (10). In conformity, then, with the above theory of absorption the NO3- in the N-n series was electrostatically attracted by Ca++ and possibly by other cations, while that of Ca++ in the A-n series was electrostatically repelled by NH4+ and possibly other cations.…”

Permeability

“…A theory of cell permeability combining an electrical theory with a colloidal theory closely resembling that of Lloyd and Free, has recently been propounded by Miss Haynes (1921), who assumes that the plasma-membrane is a gel of which the more solid phase consists pnncipally of amphoteric emulsoid colloids and the more liquid phase of a buffer mixture. At the iso-electric point the continuous phase will be in a state of minimum hydration and so will occupy a minimum volume, and also will be without charge.…”

Studies on the absorption of ammonia and nitrate by the root of Zea Mays-seedlings in relation to the concentration and the actual acidity of culture solution

“…PFEIFFE1{ (1929) and GELLHORN (1929) are of the same opmIOn. On the other hand, authors like LLOYD (19 15), FREE (1916) HAYNES (1921) and PEARSALL and EWING (1924b are inclined to consider the permeability of the protoplasm to be at its maximum at the isoeIectric point. According to LLOYD, FREE and HAYNE8, protoplasm consists of a hydrophile colloid, its permeability is determind by the change of water content of the disperse phase; the permeability will be lessened through swelling of the disperse phase, because the diffusion way of the protoplasm may become narrow through the swelling.…”