Results of dielectric constant and loss measurements at λ=9.22, 3.175, and 1.264 cm are given for a wide variety of aqueous solutions of ions and organic molecules. The water relaxation time is shortened by positive ions and lengthened by hydrogen bond-forming molecules. The properties of water are treated by a statistical method in which the numbers of molecules in four, three, two, one, and zero-bonded states are estimated from dielectric and latent heat data. Fair agreement with experiment is obtained in calculating the static dielectric constant of ice at 0° and water from 0–370°C, using Kirkwood's dielectric theory and Verwey's calculation of the dipole moment of a four-bonded water molecule. The effects of temperature and solutes on the water relaxation time are discussed in terms of this statistical method. The effective number of water molecules ``irrotationally bound,'' i.e., prevented from turning in the electric field by the ion or the organic molecule, is estimated from the depression of the low frequency dielectric constant, using a dielectric theory of mixtures. This number is zero for uncharged solute molecules but is finite for organic or inorganic ions.

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The freeze-fracture thaw-fix (FfTF) technique described in earlier papers is applied in the present work to more detailed study of the chicken erythrocyte, by transmission replicas and high resolution scanning electron microscopy (3 nm scan beam size). The three-dimensional structure of the chromatin, and possibly the non-histone protein matrix, of fractured nuclei is to a large extent retained in this method of preparation and seen in stereomicrographs. In these micrographs the helical sub-structure of the 25 nm chromatin strands can be seen at about the same resolution as that of previously published micrographs in which extracted chromatin is viewed by negative contrast or after metal shadowing. The useful resolution of the secondary electron micrographs, for a suitably mounted specimen, is shown to be as good as that of transmission micrographs of platinum-carbon replicas of the same material.

Two different freeze-fracture methods are explored for preparation of biological material for scanning electron microscopy. In the simpler method the tissues are first fixed and dehydrated. They are then frozen and fractured, and after thawing, critical-point dried. This method has already been used in a number of studies of animal tissues (heart, liver, kidney). It is applied here to the examination of plant material (leaf mesophyll cells). In the second method tissues, or cells, are first infiltrated with cryoprotectant (dimethylsulphoxide) then frozen and fractured, and not fixed until after thawing. The fixed tissues are finally dehydrated and critical-point dried. This method also has previously been used in the study of animal tissues, and is applied here to carrot protoplasts, chicken erythrocytes, and leaf mesophyll cells.