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THE determined crystal structures of a number of primary alkyl ammonium halides indicate that in such compounds the carbon atoms are arranged collinearly1 in a particular group. Thus in the case of primary amyl ammonium chloride2 the X-ray diffraction data from powders and single crystals can be completely explained by a tetragonal unit of structure containing 2NH3C5H11Cl with a = b = 5.01 A., c = 16.69 A. The space group is D42, Vd3, S41, C4v1 C41 D4h7, and the CI, N and C atoms are at o½u, ½oū, with ucl = c. 0.095. The absence of reflections in odd orders from planes (hkO) with (h + k) odd and the intensities of reflections from other planes such as (200) require the carbon atoms of the C5H11 groups to scatter X-radiation as if they are arranged collinearly in each group.

MANY viable seeds fail to germinate in darkness after imbibing water, but do so to varying degrees in solutions of several compounds. Well known promoters of germination are nitrate, nitrite and various sulphydryl and gibberellin salts1. Hydroxylammonium salts, although often cited as inhibitory1, are known to promote germination at low concentrations2. The essential action of none of these is understood and the use of nitrates in seed testing remains empirical. In seeking underlying causes for the promotive effects of nitrates we examined the germination responses to other nitrogenous salts as well as compounds affecting respiration. Cyanides were found to promote germination of many kinds of seeds in extension of the observations of Roberts3.

UPTAKE of phosphate by Saccharomyces cervisiae has three components as indicated by first-order kinetic analysis of uptake under steady-state conditions as a function of phosphate concentration. Two of these components, having Michaelis–Menten constants K m = 10−5 and 10−3, respectively, are evident on a plot of rate of uptake m against m/phosphate concentration1 (Fig. 1). Action of glycolytic and respiration inhibitors, including anaerobiosis—illustrated by the action of iodoacetate (Fig. 1)—indicates that both these components are coupled to oxidative phosphorylation associated with the action of glyceraldehyde-3-phosphate dehydrogenase. The component reaction with K m = 10−5 is found to be rate-limited by formation of adenosine triphosphate, which acts as a competitive inhibitor in the oxidative phosphorylation, and the component with K m = 10−3 by the action of hexokinase, which becomes rate-limiting for utilization of adenosine triphosphate. The coupling of phosphate uptake with glycolysis, but not its components, was recognized by Strickland2 and Goodman and Rothstein3. Rothstein4, in particular, has related the uptake to glycolytic activity at a membrane surface.

INTERRUPTION of the dark period of a 24-hr, cycle with visible radiation has been found to control reproduction in representatives of the Spermatophyta, Chordata, Arthropoda and Mollusca. Elongation, possibly cell division, in certain seedling structures is controlled by the same photoreaction as that for the photoperiodic control of reproduction in plants. It seems quite probable that the plumage cycles of birds, production of wings by aphids, prevention of diapause in some insects and the regulation of hair cycles of certain animals are controlled by the same photoreaction that controls sexual reproduction. A considerable volume of descriptive literature has grown up on this day-length phenomenon, which is a major expression of species adaptation to changing season.

THE manner in which water is adsorbed on clays has long been a matter for speculation. Structure determinations for the clay mineral hydrates throw new light on this question. These hydrates are the minerals vermicullite, hydrated halloysite and mont-morillonite. Their compositions, subject to iso-morphous replacements, are (OH)4Mg6Si8O20.8H2O; (OH)8Al4Si4O10.4H2O; and (OH)4Al4Si8O20.nH2O, respectively. Each structure contains sheets formed by joining tetrahedra of oxygen atoms around silicon atoms into interlocked hexagonal groupings as first described by Pauling1. These are combined with octahedra of oxygen atoms and hydroxyl ions about magnesium and aluminium ions, forming layers the compositions of which in a unit are given by the above formulae.

E. G. Cox1 states that l-ascorbic acid, is optically negative with α = 1.462, β = 1.68, and γ>1.70. We have examined a material isolated from peppers after the method of A. Szent-Gyorgyi2 by Dr. A. G. Grollmann, of the Johns Hopkins Medical School. This substance gives the characteristic absorption spectrum of l-ascorbic acid with a maximum coefficient3 at 2650 A.; the melting point is 188°, and the analysis (Mrs. M. S. Sherman) C, 40.80 per cent, H, 4.78 per cent (calculated for C6H8O6; C, 40.89 per cent, H, 4.58 per cent). The compound as crystallised from methyl alcohol or acetone has α = 1.465, β= 1.600±0.006, and γ= 1.747 for 5780 A. The optical sign is either positive or negative within the limit of experimental error, as is verified by the lack of curvature of the isogyre in a centred optic axis interference figure. No evidence was found for structural polymorphism, but the possibility was not rigorously eliminated. These constants, which are for crystals of the type shown in Szent-Gyorgyi's Fig. 2a2, are published since they are of value in identification of ascorbic acid and since they substantiate Cox's deduction of a plane configuration for the molecule, which is in accord with the accepted furanose ring structure.

THE first significant work on the structures of the micas was that of Maugin1, who measured the units of structure and discussed types of isomorphous replacements. Pauling2, on the basis of his co-ordination theory, proposed general structures that were shown by Jackson and West3 to be correct in some detail for muscovite. Maugin noted that the lattice dimension along the c axis of a biotite crystal was apparently one half that of muscovite, and he further observed diffuse scattering of X-rays from several crystal zones.