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The major phospholipids of two strains of Bdellovibrio bacteriovorus were characterized. Both strain UKi1, which is obligately saprophytic, and strain UKi2, which is facultatively parasitic, contained phosphatidylethanolamine and phosphatidylglycerol as their major glycerophosphatides. A branched, 15-carbon fatty acid is the major component of these alkali-labile lipids. Absent from UKi1 but present in UKi2 were three alkali-stable lipids (compounds 8, 9, and 11) which appear to be phosphosphingolipids. After acid hydrolysis, both compound 8 and 9 yield the identical phosphorus-containing substance that is water soluble, dipolar ionic, and ninhydrin positive. This substance appears to contain a C-P bond since P i could not be released from this substance by treatment with alkaline phosphatase or by very harsh mineral acid treatment. Based on chromatographic comparisons, this phosphonate appears to be a novel lipid constituent. Upon degradation, compound 8 yields 1 mol of dihydroxy long-chain base and compound 9 yields 1 mol of a trihydroxy long-chain base. These bases appear to have a 17-carbon, possibly branched, structure based on gas-liquid chromatography retention times. Degradation of both sphingolipids yields a mixture of hydroxy fatty acids, the major component being a branched, 15-carbon hydroxy acid.

Changes in extrinsic fluorescence intensity, associated with step changes in membrane potential, have been studied in intracellularly or extracellularly stained squid axons, and in lipid bilayers, using six different aminonaphthalene dyes: 1,8-TNS; 2,6-TNS; 1,8-MANS; 2,6-MANS; 2,6-ANS and NPN. In all preparations the optical signals were found to be roughly proportional to the voltage applied. All signals had a very fast initial component, which was followed in some case by a slower change in the same direction. The slow component was observed only in intracellularly stained axons, and not for all chromophores studied. 1,8-TNS, 1,8-MANS and 2,6-MANS yielded the largest fluorescence signals in all preparations. The sign of these signals was independent of the type of membrane studied. However, the fluorescence changes of 2,6-MANS were opposite to those of 1,8-TNS and 1,8 MANS. Staining of both sides of the axolemma with 1,8-MANS or 2,6-MANS showed that these dyes yield larger signals when applied to the extracellular face. The changes in fluorescence light intensity of 2,6-TNS, 2,6-ANS and NPN were smaller and their sign depended on the membrane preparation studied. The comparison of the extrinsic fluorescence signals from the nerve membrane and the phosphatidylcholine bilayer suggests strong similarities between the basic structures of the two systems. The variety of observed signals cannot be easily interpreted in terms of changes in membrane structure. A possible alternative interpretation in terms of electrically induced displacements, rotations and changes in partition coefficient of bound chromophores, is discussed.

The positive action of protonic substances in the palladium catalyzed dimerization of butadiene to 1, 3, 7 octatriene has been discovered and discussed. A reaction mechanism is proposed.

Some aspects of cell development and division of Bdellovibrio bacteriovorus strain UKi2 were examined by use of electron microscopic techniques. Under saprophytic and parasitic conditions of growth, the comma-shaped cells enlarge, elongate, and form helical filaments. The mechanism of division appears to consist of an asymmetrical constriction of the filamentous cell by the cytoplasmic membrane, accompanied by a breakdown of the outer layers of the cell wall in the division region. During regeneration of the cell wall, the flagellum and flagellar sheath are formed. The development of the flagellum of the daughter cell is initiated prior to separation of the newly formed cells from the filament. Observations of B. bacteriovorus UKi2 grown under saprophytic and parasitic conditions indicate that development and ultrastructure are similar in both modes of growth.

The oscillatory behavior of the cephalopod giant axons in response to an applied current has been established by previous investigators. In the study reported here the relationship between the familiar "RC" electrotonic response and the oscillatory behavior is examined experimentally and shown to be dependent on the membrane potential. Computations based on the three-current system which was inferred from electrical measurements by Hodgkin and Huxley yield subthreshold responses in good agreement with experimental data. The point which is developed explicitly is that since the three currents, in general, have nonzero resting values and two currents, the "Na" system and the "K" system, are controlled by voltage-dependent time-variant conductances, the subthreshold behavior of the squid axon in the small-signal range can be looked upon as arising from phenomenological inductance or capacitance. The total phenomenological impedance as a function of membrane potential is derived by linearizing the empirically fitted equations which describe the time-variant conductances. At the resting potential the impedance consists of three structures in parallel, namely, two series RL elements and one series RC element. The true membrane capacitance acts in parallel with the phenomenological elements, to give a total impedance which is, in effect, a parallel R, L, C system with a "natural frequency" of oscillation. At relatively hyperpolarized levels the impedance "degenerates" to an RC system.

The ulstrastructural study on Porphyridium aerugineum showed vesicles in the peripheral cytoplasm which contain fibrous material similar in appearance to the cell sheath. In most respects the morphology of P. aerugineum, a freshwater form, is very similar to that of P. cruenturn, a marine species. However, there is a marked difference in the shape of the phycobilisomes which are attached to the chloroplast lamellae. In P. cruentum the phycobilisomes are always spherical or oblate, whereas in P. aerugineum they are disk shaped. The possibility is considered that the shape of the phycobilisomes may be determined by the phycoerythrin and phycocyanin content.

Two freshwater blue-green algae, Tolypothrix tenuis and Fremyella diplosiphon , and an oscillatorialike marine alga, were found to possess structures on the photosynthetic lamellae which appear to correspond to the phycobilisomes of red algae. These homologous structures are important because they contain the phycobilins which are accessory pigments involved in photosynthesis. As in the red algae, the phycobilisomes were attached on the outer side of each lamellae, i.e., the side facing away from its own membrane pair. Although our study on Anacystis nidulans has not thus far revealed the presence of phycobilisomes, some observations were made on the structure of the polyhedral bodies. After negative staining, the polyhedral bodies were seen to be composed of regularly spaced subunits arranged in a crystalline array. Elongated segmented rods, which differed from the polyhedral bodies, were found in the nuclear region of apparently healthy Tolypothrix cells.

Dipeptides of different amino acids have been studied by NMR in aqueous solutions at different pH values. The results obtained are discussed in terms of the different contributions to the chemical shift of the α-CH protons.

The deoxyribonucleic acids of 70 hyphomicrobia were examined at equilibrium in neutral CsCl density gradients. The guanine plus cytosine (%G+C) content was estimated to range from 59.2 to 66.8% G+C. The strains could be divided into three groups with different base composition of their DNA; 61.0±1.1%, 64.1±0.6%, and 66.5±0.6% G+C. The values are compared with those for the base composition of DNA of a number of phototrophic, budding bacteria.

Holt, Stanley C. (Dartmouth Medical School, Hanover, N.H.), S. F. Conti, and R. C. Fuller . Effect of light intensity on the formation of the photochemical apparatus in the green bacterium Chloropseudomonas ethylicum . J. Bacteriol. 91: 349–355. 1966.—When the green bacterium Chloropseudomonas ethylicum was grown at various light intensities, the formation of the photosynthetic vesicles was found to be an inverse function of the light intensity at which the cells were grown. The specific chlorophyll content of isolated vesicles varied as the light intensity was changed over a wide range. Thus, the regulation of chlorophyll content in C. ethylicum in response to a change in light intensity is achieved both by a change in the number of vesicles that are formed and by a change in the specific chlorophyll content of these vesicles.

Changes in refractility and optical density occurring in individual spores of Bacillus cereus T and B. megaterium QM B1551 during germination were investigated by use of a Zeiss microscope photometer. The curves revealed that the germination process in single spores had two distinct phases; an initial rapid phase was followed by a second slower phase. Under the experimental condition employed, the first phase of germination of B. cereus spores lasted for approximately 75 ± 15 sec, whereas the second phase lasted for 3 to 4.5 min. In B. megaterium spores, the first phase was observed to last for approximately 2 min and the second phase for more than 7 min. The duration of the second phase was dependent on conditions employed for germination. The kinetics of the first phase were strikingly similar under all conditions of physiological germination. Time-lapse phase-contrast microscopy of germinating spores also revealed the biphasic nature of germination. It was postulated that the first phase represents changes induced by an initial partial hydration of the spore and release into the medium of dipicolinic acid, whereas the second phase reflects degradation of the cortex and hydration of the core.

Conti , S. F. (Dartmouth Medical School, Hanover, N.H.), and Peter Hirsch . Biology of budding bacteria. III. Fine structure of Rhodomicrobium and Hyphomicrobium spp. J. Bacteriol. 89: 503–512. 1965.—The ultrastructure of 14 strains of hyphomicrobia, and of Rhodomicrobium vannielii , was investigated by means of electron microscopy of thin sections. The majority of the strains of hyphomicrobia possessed a well-developed internal membrane system, which appeared to be derived by invagination from the cytoplasmic membrane. The subcellular organization of the hyphomicrobia and R. vannielii was investigated.

The mechanism of inhibitor-tolerant respiration in Rhodotorula glutinis was studied. This inhibitor-tolerant respiratory pathway was not due to the presence of an excess of cytochrome c oxidase, nor to the operation of an inhibitor-resistant cytochrome c oxidase. Carotenoids do not appear to be involved in this respiratory chain pathway; data are also presented which show that the inhibitors penetrate into the cell. Although the initial rate of oxygen uptake by intact cells was not inhibited in the presence of cyanide or antimycin A, in the presence of these inhibitors the rate of oxygen uptake decreased significantly when the oxygen concentration fell below 100 mum. This change in rate of oxygen uptake as a function of pO(2), suggests that a respiratory chain with a low affinity for oxygen operates in the presence of inhibitors. The characteristics of this alternate pathway are described.

The sequence of events occurring during the germination and outgrowth of appendage-bearing spores of Clostridium bifermentans was studied by phase-contrast and electron microscopy. The mature spore was characterized ultrastructurally as having the normal spore components as well as long tubular appendages which orginated from the surface of the spore coat. Spores were incompletely enclosed by a distinctly laminated exosporium which possessed hairlike projections on its outermost layer. During germination, structural changes were observed in the core, core wall, cortex, and spore coat layers. Cortical material was extruded from the spore during outgrowth, which usually occurred from the pole opposite the appendages. The subunits comprising the structure of the appendages and the morphology of the mature appendages were observed. No discernible changes could be observed in the spore appendages during germination and outgrowth.

Small granules with a diameter of approximately 350 A are attached to the chloroplast lamellae of the red alga Porphyridium cruentum. To some extent, their size depends on the culture conditions and the age of the cell. It was possible to preserve the granules only with aldehyde prefixation. It can be seen that fixed or negatively stained granules are comprised of smaller subunits. The granules are arranged regularly on the lamellae in repeating rows with a center-to-center granule distance of 400 to 500 A. Attempts at characterization of these chloroplast granules revealed that they are resistant to hydrolysis by ribonuclease and appear to be structurally unaffected by methanol-acetone extraction. Because of their close association with the chloroplast lamellae, they are considered as possible sites of phycobilin concentration. This possibility is supported by two observations: when the phycobilins are removed, the granules disappear; and, when the chlorophyll and stainable membrane portions are selectively removed, the phycobilins and granules are still present. It was found that all other marine red algae examined had granules which were associated with the chloroplast lamellae.

An electron microscopic examination of Porphyridium cruentum revealed the presence of mitochondria which had been reported absent in this aerobic organism. The chloroplast in this red alga was found to contain small granules (about 320 A) regularly arranged along the parallel chloroplast lamellae. The chloroplast granules differ in size and staining intensity from the ribosomes located in the cytoplasm. Two tubular elements are described. One type (450 to 550 A) is associated with the Golgi bodies. Another type (350 A), in the cell periphery, is believed to connect the endoplasmic reticulum and the cell membrane. Daughter nuclei were found to be positioned at opposite ends of the cell prior to commencement of cell division. Cytokinesis is accomplished by an annular median constriction causing the gradual separation of the chloroplast, pyrenoid, and other cell organelles, resulting in two equal daughter cells. No appreciable differences were observed between cells grown in high light (400 ft-c) and low light (40 ft-c). Structural differences between young and old cells were compared.

Conti , S. F. (Brookhaven National Laboratory, Upton, N. Y.) and M. E. Gettner . Electron microscopy of cellular division in Escherichia coli . J. Bacteriol. 83: 544–550. 1962.—Exponentially growing cells of Escherichia coli were fixed in formalin, exposed to uranyl nitrate, dehydrated at low temperatures with ethanol, and embedded in methacrylate. Polymerization was carried out at −70 C, by exposure of specimens to radiation from a cobalt 60 source. Electron micrographs revealed that cellular division occurs by the centripetal growth of the cell wall. The fine structure of the cytoplasm, nuclear apparatus, cell wall, and cytoplasmic membrane was also studied.

Electron microscopic studies of thin sections of filaments, knots, resettes, gonidia, and gonidial-forming filaments of Leucothrix mucor were carried out. The cell wall is typical of gram-negative bacteria, with a double outer layer of variable thickness, a single thin middle layer which is probably peptidoglycan, and a double inner layer which is the cell membrane. The transverse septa of these filaments show two peptidoglycan layers, and no clearly demarked outer layer. During gonidial formation, there is a gradual rounding up of the cells, and the transverse septa become part of the gonidial wall. The cell membrane contains many invaginations, both along the outer wall and along the transverse septa. Thin sections through rosettes show the holdfast as material which is a heavily-staining amorphous material peripheral to the outer wall layer. Sections through knots show highly contorted cell walls, closely appressed. Fibrillar nuclear material, ribosomes, and storage granules can be seen within the cytoplasmic matrix.

High-resolution nuclear magnetic resonance spectra at 100 MHz have been obtained on poly-N-methyl-L-alanine in the chloroform–trifluoroacetic acid system under various conditions of solvent composition. Different spectra are observed for the CH3–Cα, Cα–H, and N–CH3 protons. On the basis of conformational analysis an interpretation of the NMR results was attempted.

The dynamics of 180° domain walls has been studied in three hexagonal ferrite single crystals with a high uniaxial anisotropy. By means of an improved pulsed magnetic‐field technique and by analysis of the experimental method, we can observe the single‐wall mobility η just from the initial domain‐wall motion, i.e., for the lowest values of the internal field Hi. In the examined ferrimagnetic oxides the initial domain‐wall motion shows, as in cubic ferrites, a constant mobility η of the order of 102 cm/sec/Oe. Such a dynamical situation is followed by a more complex one, characterized by mobilities at least one order of magnitude lower. Moreover, we have indications that the domain‐wall apparent mass increases with increasing wall acceleration. We discuss the above‐mentioned phenomena in connection with the possible spin‐wave excitation during the wall movement.

Holt, Stanley C. (Dartmouth Medical School, Hanover, N.H.), S. F. Conti, and R. C. Fuller . Photosynthetic apparatus in the green bacterium Chloro-pseudomonas ethylicum . J. Bacteriol. 91: 311–323. 1966.—When cells of Chloro-pseudomonas ethylicum were broken by ballistic disruption and examined by electron microscopy, vesicles 1,300 to 1,500 A long and 300 to 500 A wide were found to rim the periphery of the cell. Examination of these vesicles obtained by disruption with a French pressure cell and purified by density gradient centrifugation revealed inter-connections between the vesicles. During sonic and Mickle disruption of the cells, chlorophyll was released at a lower rate than soluble cytoplasmic components, but faster than the membrane-bound enzyme succinic dehydrogenase. Unlike the situation that exists in the purple photosynthetic bacteria, it appears that the chlorophyll in the green bacteria is contained as part of a structure which may be differentiated both structurally and functionally from the bacterial cytoplasmic membrane.

The fine structure of cells of Saccharomyces cerevisiae engaged in the formation of ascospores was studied in electron micrographs of ultrathin sections. Although the mode of the first reduction division could not be clearly determined, the second nuclear division appeared to proceed in a manner similar to that observed previously during vegetative division. That is, division by constriction of the existing nucleus occurs without dissolution of the nuclear membrane and without involvement of discrete chromosomes. Variously shaped areas of low electron density were discerned within the nucleoplasm; these had not been previously seen in the vegetative nucleus. The significance of this nuclear differentiation and its possible similarity to nuclear structures reported in bacteria and an imperfect fungus are discussed. The cytoplasmic membrane appears first in the developing ascospore. The formation of an outer coat and an inner coat then follows. The cytoplasmic vacuole was observed not to be incorporated into the spore. An unusual intracytoplasmic membrane was observed in the spore and appeared to be at least temporarily continuous with the nuclear membrane.

Ten bacteriophages that attack and lyse saprophytic strains of Bdellovibrio bacteriovorus were isolated. Morphological, serological, and host-range studies revealed that there were four different bdellovibrio phages present among the isolates. One of the phages lysed a strain of B. bacteriovorus that requires the presence of a suitable bacterial host for growth. The phage attached to the bdellovibrio cells in the absence of the bacterial host cells; lysis occurred only in the presence of host cells. The 19 saprophytic bdellovibrio strains employed in the phage host-range studies were grouped on the basis of their susceptibility to phage lysis.

A system composed of two ionic solutions, solution (′) and solution (″), which are isotonic and separated by a membrane permeable to the solvent and to at most two of the ionic components present in the solutions, is considered. The variations of the difference of electric potential between solution (″) and solution (′), in the steady state and for zero electric current, corresponding to variations in the composition of e.g. solution (′), are found to depend only on the properties of the membrane phase at the boundary with solution (′). This result is deducible under loose assumptions as to the dependence of the properties of transport and absorption of the permeant components in the membrane on their activities in solution. It can therefore be particularly useful for the study of systems, like biological membranes, whose structural and chemical composition is so poorly known that any assumption about that dependence is hardly justifiable.

The 1H and 13C NMR spectra of antibiotic Viomycin sulphate and its constituent aminoacids in H2O and D2O were examined in a wide range of pH values. The spectra were analysed by proton spin-spin decoupling experiments and measurements of the relative intensities of the resonance and chemical shift values. Exchange experiments were also carried out and an almost complete assignment of the resonances of the spectra was possible. The data obtained are discussed in terms of possible structures for Viomycin and the presence of intramolecular hydrogen bonds. Some information about the conformation of the molecule is also given. A tentative assignment of the 13C spectrum of Viomycin is given and the experimental 13C chemical shift values compare well with the theoretical ones evaluated by Grant's rule.

A re-determination of the energy barrier for the internal rotation of N, N-dimethylformamide has been carried out by proton magnetic resonance under refined experimental conditions. Consistent data have been obtained for ΔE, ΔG≠, and v0 from different experiments utilizing 60 Mc/s and 100 Mc/s spectrometers including homonuclear double resonance and the use of deuterium substitution. The results are compared with the range of values previously reported in the literature.

Hydroquinone derivatives have been obtained by stoichiometric and catalytic addition of several organic reagents to p -benzoquinone π-bonded to triphenylphosphine Pd° complexes.

The synthesis of π-allyl palldium (II) compounds, [PdCl(CnH2n—1)]2 from olefins and PdCl2 under mild conditions is described. The mechanism of the reaction and the role of the solvent are discussed with reference to some aspects of the catalytic activity of palladium (II) salts in non-aqueous solvents. The behaviour of PtCl2 under similar reaction conditions is compared with that of PdCl2.

The appendages of Clostridium bifermentans UK-A 1003 spores were shown to originate from a substance located just exterior to the outer forespore membrane. The dense spore coat develops along the periphery of this material, and, as the appendages develop in the cytoplasm, the coalescing spore coat intervenes between the appendages and their origin. Freeze etching revealed that the appendages are in the form of distinct fibers in proximity to the mature spore body. These fibers form a network around the spore, seemingly encasing it and insuring that the appendages remain attached to the mature, free spore. The inner wall of each appendage tubule is lined with fibers whereas the outer surface is smooth. The developing exosporium contained several layers consisting of small (3 nm) globular subunits; the outer exosporial surface is composed of relatively unstructured material.

Jacobs , N. J. (Dartmouth Medical School, Hanover, N.H.), and S. F. Conti . Effect of hemin on the formation of the cytochrome system of anaerobically grown Staphylococcus epidermidis . J. Bacteriol. 89: 675–679. 1965.—The cytochrome content and respiratory capacity of cells of a strain of Staphylococcus epidermidis grown in complex media under aerobic and anaerobic conditions were determined. Difference spectra revealed cytochromes of the a, b 1 , and o types in aerobically grown cells. These cells respired at a rate of 66 μliters of O 2 per hr per mg of cells (dry weight). The cytochrome content of anaerobically grown cells was markedly reduced, and trace amounts only of cytochromes of the b 1 and o type were visible. The respiratory rate, with glucose as substrate, was reduced to about one-tenth of that observed in aerobically grown cells. Cells grown anaerobically in medium supplemented with hemin had as high a content of pigments resembling cytochromes b 1 and o as did aerobically grown cells; the respiratory rate was 60% of that observed in aerobically grown cells. Cytochrome of the a type, similar to that found in aerobically grown cells, was not detected.

The cordinative reactivity and stability of the species Pt(PPH 3 ) 2 are reported; its reactivity towards small molecules is compared with that of a chemisorption center on a metal surface. The relation between the coordinative unsaturation and chemical behaviour of Pt(PPH 3 ) 2 and the carbenoid character for the platinum atom is discussed.

The effect of the Void on the thermal and epithermal neutron Spectrum indices and on the fast fission ratio was measured in the EURATOM critical facility ECO, using the detector activation and the back-to-back fission chamber technique. Several irradiation measurements were performed on uranium carbide and uranium metal fuel cluster. AS coolant the organic liquid diphyl (eutectic mixture C 12 H 10 C 12 H 10 O) or the air were used. The experimental results obtained are quoted and discussed, particularly for what concerns the void differential effect.

Conti , S. F. (Dartmouth Medical School, Hanover, N.H.), and T. D. Brock . Electron microscopy of cell fusion in conjugating Hansenula wingei . J. Bacteriol. 90: 524–533. 1965.—The heterothallic yeast Hansenula wingei is a favorable organism for the study of the process of cell fusion, since strong agglutination of cells of the two mating types ensures a high percentage of cell fusions. The initial agglutination reaction results in cell-wall deformation, so that the walls in the region of contact are tightly appressed over an extensive area. The fusion process is initiated when the walls of two cells elongate, and this elongation seems to be restricted to the region where the cells touch. Occasionally, one cell is seen to push in the wall of the other, but in many cases both cells elongate equally, as would be expected in an isogamous organism. The precise disposition of the elongating wall probably reflects the manner in which the cells initially become associated in the agglutinated cell clump. Soon after wall elongation begins, cell-wall fusion occurs along the margin of contact. Only after fusion is complete is the wall separating the two cells dissolved away. If wall dissolution begins at one edge of the conjugation tube, a flap is formed in which can be seen the remnants of the fused walls. Alternatively, dissolution can begin at the center of the conjugation tube, proceeding towards the outside. Conjugating cells are uninucleate, and the nuclei are large and frequently lobed or elongated. After the conjugation tube is formed, the nuclei migrate towards the center, and fusion occurs only over a small region where the nuclear membranes come in contact. After nuclear fusion, the first diploid bud forms from the conjugation tube and at right angles to the tube axis. The diploid nucleus then migrates into this bud. Frequently, in the later stages of conjugation, a large vacuole develops in each of the original cells. All of the above events will occur in a medium devoid of a nitrogen source and in which vegetative budding will not occur.

The distribution of the electrical potential around the edge of the field plate in a silicon planar diode has been solved by means of a computer. The breakdown voltage related to this region has been derived as a function of impurity doping in silicon and of oxide thickness. If the oxide layer is not thick enough, avalanche breakdown voltage is often considerably lower than the value allowed by the material. The effect of Q ss has been found to be negligible. Breakdown voltage vs. gate voltage measurement on gated diodes and avalanche light emission support an edge breakdown mechanism. Breakdown voltage on field plated diodes matches rather well with the calculated values. It normally drifts towards higher values and during this walkout a hot carrier current is collected by the field plate. The field plate current is fairly proportional to avalanche current and increases with bulk doping. A new planar diode structure suitable for a BV up to 900 V has been designed. The discharge voltage in air between field plate and equipotential ring (EQR) is shown to be correlated with the actual field at the edge.

The polar lipids of the autotrophically grown, obligately anaerobic, photosynthetic bacterium Chromatium strain D were separated by paper chromatography. Four major phospholipids were identified: lysophosphatidylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin. In addition, three glycolipids were observed and characterized, namely, monoglucosyldiglyceride, which is found in other biological systems, and (mannosyl, glucosyl)-diglyceride and (dimannosyl, glucosyl)-diglyceride, which heretofore have not been observed in nature.

Pick‐up coil systems suitable for magnetization measurements are shown to be useful also for the automatic recording of the internal magnetic field of an ellipsoidal specimen. The probe is made to operate in this way not with the need of special devices, but simply by properly changing the coil's position. The accuracy in the measurement is essentially limited by eddy current effects which cause distortion in the signal; it depends strongly on the geometry of the coils and of the sample, and on the differential susceptibility of the tested material. An open flux hysteresigraph that utilizes three coils is proposed as an application of this method and is shown to be particularly advantageous for hard materials.

Linear dimerisation of 1,3-butadiene in the presence of formic acid has been studied. 1,7-Octadiene has been obtained in good yield as the final product.

CHOLINERGIC substrates have been found in a gauche conformation (G), skewed about the Cα–Cβ bond of the (CH3)3N+–CH2–CH2–O cholinic fragment in a number of crystal structures1–11. Sulphur and selenium isologues, on the other hand, with the (CH3)3N–CH2–CH2–(S,Se) group, are normally in the extended trans conformations (T)10,12,13. In agreement with the assumption that the reduced spectrum of biological activity of many rigid analogues and Cα or Cβ substituted derivatives of acetylcholine can be partially ascribed to the reduction in conformational flexibility14–17, a theoretical investigation18 predicted the existence of four almost isoenergetic conformations TTTT, TGTT, TTGT and TGGT about the ψ0, ψ1, ψ2 and ψ3 internal rotation angles schematically represented in Fig. 1.