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VARIOUS attempts have been described1 to acetylate alginic acid by means of acetic anhydride or acetic acid, without or with catalysts, for example, pyridine, acids, etc. Some of the products thus obtained were probably degraded, and it appeared of interest, therefore, to find out whether the acetylation of alginic acid can be done by a relatively mild method; for this reason the interaction with ketene was studied.

Volcanic dome-building episodes commonly exhibit acceleration in both effusive discharge rate and seismicity before explosive eruptions. This should enable the application of material failure forecasting methods to eruption forecasting. To date, such methods have been based exclusively on the seismicity of the country rock. It is clear, however, that the rheology and deformation rate of the lava ultimately dictate eruption style. The highly crystalline lavas involved in these eruptions are pseudoplastic fluids that exhibit a strong component of shear thinning as their deformation accelerates across the ductile to brittle transition. Thus, understanding the nature of the ductile-brittle transition in dome lavas may well hold the key to an accurate description of dome growth and stability. Here we present the results of rheological experiments with continuous microseismic monitoring, which reveal that dome lavas are seismogenic and that the character of the seismicity changes markedly across the ductile-brittle transition until complete brittle failure occurs at high strain rates. We conclude that magma seismicity, combined with failure forecasting methods, could potentially be applied successfully to dome-building eruptions for volcanic forecasting.

A VARIETY of mechanisms underlie the pharmacological blockade of membrane excitability. Some drugs seem to reduce the frequency at which ion channels open; a good example is the effect of curare on acetylcholine receptor channels at normal resting potentials. Another sort of mechanism may account for the action of many local anaesthetics and related drugs containing charged ammonium groups. It is postulated that such molecules block transmembrane currents as they bind to sites within open ion channels, much like a plug in a drain, with the important difference that the events occur on a millisecond time scale. This model, which we shall call ‘open-channel blockade’, was first applied to the effect of internal tetraethylammonium ions on K+ channels in squid axon1 and more recently to similar actions of local anaesthetics on acetylcholine receptor channels2–4 and on electrically excitable Na+ channels5. (Curare seems to exert an additional open-channel blockade at high negative potentials6,7.) The concept of open-channel blockade would receive direct experimental support from the demonstration that the blockade is exerted even if the blocking molecule is not bound to the channel (or indeed is not present at all) until after the channel opens. Such a demonstration is made possible by a drug that (1) blocks acetylcholine receptor channels in Electrophorus electroplaque, and (2) is created, in less than a millisecond, by a flash of light.

IT has been shown1 that birefringent fully swollen calcium alginate fibres of 0·4 mm. diameter contract on replacing the bifunctional calcium ion by the mono-functional sodium ion. Ingersoll and Johnson suggest2, inter alia, that the contraction is due to osmotic de-swelling rather than to devulcanization brought about by ionic exchange1. This explanation is unacceptable for the reasons below.

THE process described by Masson1 as “cytocrine” implies that the melanocyte is the active partner in the transfer of melanin granules to Malpighian cells. Cruickshank and Harcourt2 pointed out this implication and advanced evidence that, as judged by the activity of the cell membrane, the epithelial cell appeared to play a more active part in the transfer of melanin granules. Recent investigations indicating that the Malpighian cells may be the active partner in phagocytosing melanin granules led Fitzpatrick and Breathnach3 to the development of their concept of an “epidermal melanin unit” in which the functional unit of pigmentation is seen as a melanocyte and the pool of epidermal cells to which it is connected. Such units were recently demonstrated in amphibian skin by Hadley and Quevedo4, who in addition provided evidence that the rate at which melanin granules are carried away from melanocytes may also be a decisive factor in determining the rate at which they are synthesized. This useful concept is a significant advance in the study of “melanokinetics”5, but it does not embrace other cells transporting melanin, such as leucocytes.

IN estimating the size of very large colourless molecules by light scattering, according to the transmission method1, the following relationships are relevant: where τ is the turbidity of the solution to be tested, l is the optical path-length, J and J 0 are the intensities of incident and transmitted light, c is the solute concentration, λ is the wave-length of light, M is the weight average molecular weight of the solute, N is Avogadro's number, µ, and µ0 are the refractive indices of solution and solvent, Q exp. and Q theor. are the particle dissipation factors, the former to be determined from the wave-length dependence of turbidity and refractivity and the latter from analytical expressions due to Doty and Steiner1 and Bueche, Debye and Cashin2. The dependence of β′ on molecular dimensions is shown in Fig. 1; the limiting values, β′∞, are respectively 2.0, 1.7, 1.45 and 1.0 for spheres, monodisperse coils, polydisperse coils and thin rods. It will be seen that a comparison between β and β′∞ gives information regarding the shape of sufficiently large scattering particles. The approximate value of M for such solutes can be obtained from (3), in conjunction with an extrapolation method proposed by Cashin and Debye3, in which (Hc/τ)λ c → 0 is plotted against (µ0/λ)2, thereby enabling an estimation of the intercept for (µ0/λ)2 = 0. Inserting the reciprocal of this intercept in (2) leads to Q λ exp.; and comparison of this with Q λ theor. enables one to compute the order of magnitude of the molecular dimension.

Recently we described a procedure for preparing antibodies to the acetylcholine receptor (AChR) based on immunoglobulin idiotypes and on the hypothesis that, regardless of functional differences, macromolecules of the same specificity will show structural homologies in their binding sites. Antibodies were prepared in rabbits to a structurally constrained agonist of AChR, trans-3,3'-bis[alpha-(trimethylammonio)methyl]azobenzene bromide (BisQ). These antibodies mimicked the binding specificity of AChR in its activated state--agonists were bound with affinities that were in accord with their biological activities and antagonists were bound poorly. Rabbits were then immunized with a specifically purified preparation of anti-BisQ to elicit a population of antibodies specific for the binding sites of anti-BisQ. A portion of the anti-idiotypic antibodies produced in the second set of rabbits cross-reacted with determinants on AChR preparations from Torpedo californica, Electrophorus electricus and rat muscle. Moreover, several of the rabbits showed signs of experimental myasthenia gravis, in which circulating AChR antibodies are typically found. To devise a more direct route to monoclonal anti-receptor antibodies we based our strategy on acceptance of the concept of the anti-idiotypic network theory of Jerne. According to this theory, injection of an antigen elicits, in addition to antibodies to the antigen, other populations that include anti-idiotypic antibodies directed at the combining sites of the antigen-specific antibodies. If the antigen-specific antibodies recognize a ligand of a receptor, then the anti-idiotypic antibodies should bind receptor. Thus, when a mouse is immunized with a bovine serum albumin conjugate of BisQ (BisQ-BSA), it should be possible to expand populations of spleen cells that secrete antibodies which bind anti-BisQ and AChR, in addition to populations specific for BisQ. Fusion of the spleen cells with an appropriate myeloma line should yield monoclonal anti-AChR antibodies. Here we report the success of this approach and its implications.

FOR the further development of the theory of reaction kinetics and polymerisation in the condensed state, it is important to compare the rate of an association reaction, of the type a + b c, in solution and in the gas phase. In this communication experiments are reported from which such a comparison is possible.

THE decomposition of dicyclopentadiene into cyclopentadiene is an inverse diene synthesis. It was found previously1 that in paraffin solution the reaction is monomolecular and that the rate constant is given by k = 6.0 × 1012 e34000/RT sec.1.

IF a chemical reaction takes place with change of colour, colorimetric measurements at time intervals form a convenient method for examining the kinetics of the reaction. It is possible to improve the older methods1 based on this principle by the use of the Pulfrich-Stufenphotometer by Zeiss. This instrument permits of measurements: (1) at constant temperature; (2) for a large range of concentrations; (3) with monochromatic light; (4) in coloured and very volatile solvents.

Cyclopentadiene can be converted catalytically, by trichloroacetic acid, into a brown-red polycyclopentadiene–trichloroacetic acid ester, (I), the colour of which is due to conjugated double bonds1. If this ester is brought into contact with sufficiently concentrated strong acids, a dark blue, almost black, molecular compound, (II), is immediately formed. In tests in which the concentrations are small, or in which weaker acids are used, the colour of this compound is greenish-blue or green.

Diene syntheses are reversible associations of the type The equilibrium constant K = has been measured for four of these reactions. (1) cyclopentadiene + -naphthoquinone l cyclopentadiene--naphthoquinone. (2) cyclopentadiene + benzoquinone l cyclopentadiene-benzoquinone. (3) cyclopentadiene + cyclopentadiene l dicyclopentadiene. (4) cyclopentadiene + acrolein l endomethylene-tetrahydrobenzaldehyde.

Cyclopentadiene can be converted, catalytically by trichloroacetic acid (HA), into a brown-red polycyclopentadiene trichloroacetic acid ester (I). The colour of this adduct is due to conjugated double bonds1, which are also responsible for its proton acceptor properties2, namely, for the fast reversible reaction: where (II) is a blue salt-like adduct, formed by transfer of a proton from (HA) to (I).

THE reaction cyclopentadiene + cyclopentadiene diclopentadiene is reversible, and is bimolecular in the direct and monomolecular in the reverse directions. No observation indicates that a chain mechanism is involved. The association was measured in benzene solution between 15° and 55°, and the decomposition in paraffin solution between 135° and 175°. The Arrhenius equation k = ZeE/RT proved to be valid.

Conversion of Cyclopentadiene into New Bicyclopentyl Derivatives: Structure Determination with the Help of Proton Magnetic Resonance Spectroscopy

IN the Arrhenius equation , C is the collision frequency and P the steric factor. For gas reactions the kinetic theory gives C 1011. Bimolecular reactions in solution can be divided into two main types1: (a) reactions involving simple ions where Z 1011; (b) reactions involving molecules with many internal degrees of freedom, where Z 1011 (slow reactions). For reactions (a) a statistical mechanical treatment shows2 that P should be of order unity and here it can be concluded that C is of order 1011. For reactions (b) a statistical mechanical calculation of P is difficult and thus it is possible a priori that C falls below the gas value by several powers of ten.

IN previous communications1 it has been shown that copper sulphide, activated by oxidizing a part of its surface into copper sulphate, is a catalyst for the low molecular polymerization of isobutene. It has now been found that the main product of the catalytic process is a mixture of the two 2: 2: 4-trimethylpentenes which on hydrogenation were converted into 2: 2: 4-trimethylpentane. This latter compound was identified by determining the boiling point, the specific gravity, the refractive index, the melting point and the mixed melting point with an authentic sample. A detailed description of the experiments will be published elsewhere.

THE interaction of simple ions with plant cells has been frequently studied, and it has been found that in some cases cations and anions are both absorbed in the vacuoles1, while under different conditions the readjustment of the salt content occurs mainly by ion exchange2. The experiments now to be described belong to the latter type ; but, so far as I am aware, this is the first time that the ionic adsorption by a plant material has been systematically studied under flow conditions comparable to those prevailing in inorganic chromatographic adsorption analysis.

DOHLE bodies, which occur as blue-staining inclusions in neutrophils on Romanowsky-stained preparations, have been described as an acquired anomaly in various conditions in man1–5. They have also been reported as a familial anomaly associated with platelet abnormalities in 4 families so far6 and are then denoted by the eponym, May–Hegglin syndrome. They have not been reported in experimental animals.

Grundlagen der analytischen Chemie und der Chemie in wasserigen Systemen Von Prof. F. Seel. Pp. 348. (Weinheim/Bergstr.: Verlag Chemie, 1955.) 29 D. marks.