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Germination of Panicum capillare L. caryopses induced by solutions of ethanol and ethyl ether was prevented by application of pressure >1 MPa during the period of exposure to the anesthetic. This effect of pressure indicates that germination is correlated with expansion at a site of anesthetic action in a cell membrane. The effects of several other anesthetics were measured on germination of P. capillare seeds. Ethanol, chloroform, and ethyl ether had the highest activity. Methanol and isopropanol were inactive. The effective compounds are thought to distribute preferentially to lipid-solution interfaces in cell membranes of the seeds.

Leakages of amino acids and/or fluorescent material as functions of temperature between 15 and 40 C are reported for imbibed seeds of Avena fatua L., Lactuca sativa L., Barbarea vulgaris R. Br., Amaranthus albus L., Abutilon theophrasti Medic., Lychnis alba Mill., Daucus carota L., Setaria faberi Herrm., Setaria viridis (L.) Beauv., and Datura stramonium L. The leakage indicates prominent increase in permeability of the plasmalemma in the 30 to 35 C range for 8 of the 10 kinds of seeds studied. Germination of the seeds at constant temperatures or with daily shifts in temperature is related to the membrane transition temperature for permeation by amino acids. Seeds of A. albus and A. theophrasti, which did not show membrane changes in the 25 to 40 C range, germinated best at 35 to 40 C; the other seeds germinated best below 30 C. Seeds of B. vulgaris showed rapid permeation of limiting membranes upon initial wetting with water, which was indicative of membrane disorder when dry. Leakage under anaerobiosis was observed for S. faberi seeds.

growth over an unseasonal warm period. Instead, they use the cold days of winter to prepare for a resurgence of growth in the spring. These are aspects of dormancy or arrest in development under conditions favorable for growth. Such rest or dormancy periods are shown by spores, seeds, and buds of vascular plants as well as by spores of fungi and bacteria. A fully developed seed contains an embryonic plant having an initiated root and shoot with food reserves in the

An ionization spectrometer for intensity measurements is described. The coaxial rotation of chamber and crystal is accomplished on precision ball bearings in place of the usual conical bearing. The scales of the instrument are projected for ease in operation. A simple ``manual'' recorder is included.

effects of ultraviolet radiation on plant growth, noted that injury was found only when the radiation was used to interrupt a dark period. Results of a more detailed study on the effect of ultraviolet radiation on a higher plant are reported here. These results point to a similarity in the nature of photoreactivation in higher plants and in lower plants and animals. METHODS.-Preliminary experiments indicated that soybean leaves (Glycine max, var. Wabash) irradiated with ultraviolet lost chlorophyll when kept in darkness for about 3 days, while leaves exposed to visible light for about 10 min. following ultraviolet irradiation remained green during the same dark period. The loss of chlorophyll in ultraviolet-irradiated leaves has been used as a measure of radiation damage and has been found to be

Flowering of Chenopodium rubrum L., selection 374, was examined with respect to an endogenous circadian rhythm, the state of phytochrome, and the result of changing the form of phytochrome during a single dark period of 2 to 96 hours interrupting continuous light. Darkness was imposed either 4 or 5 days after seeds were placed on moist filter paper in Petri dishes.The following working hypothesis, which is partly retrospective, is projected to explain the main features of the experimental results. Flowering is controlled by a product of the enzymatic action of the far-red absorbing form of phytochrome (Pfr) on a single but unknown substrate. In acting, Pfrfinally reverts to the inactive red-absorbing form of phytochrome (Pr) or is changed from the Pfrform in some other way. The available substrate, if not utilized by Pfraction, is soon depleted by other reactions. The substrate for Pfraction is low during the skotophile but high during the photophile phases. The significant time for phasing is the beginning of darkness. The initial substrate supply appears to be derived from the preceding light period but some time in the region of the 9th to 12th hour of darkness a significant rhythmic change of substrate starts up. The dependence of flowering on the time that darkness is interrupted by light is directly related to a rhythmic change in the optimum Pfrlevel required for the processes leading to flowering.The role of the endogenous rhythm in flowering under natural conditions is questioned. Similarities that are shown in the control of flowering, whether the display is governed by an endogenous rhythm or by a daily photoperiodic cycle, indicate that phytochrome acts as a "pacemaker". It is suggested that the distinct ecotypic populations of C. rubrum that differ in flowering response have dissimilar levels and rates of supply of substrate for phytochrome action. In C. rubrum-374, complete reversion or loss of Pfrdoes not occur during a long dark period of 72 hours at 20 °C, but Pfrdoes decrease to low levels.A hydrodynamic system is discussed as an analogy to rhythmic flowering response.

Action spectra between 4100 and 8500 A for seed germination and radicle elongation were measured for Nemophila insignis and Lactuca sativa var. Great Lakes and between 6500 and 8500 A for seed germination of Lamium amplexicaule. The responses observed are features of the continued excitation of the photomorphogenic pigment in those regions of the spectra where both pigment forms have appreciable absorptivities.

A small differential thermal analysis unit that embodies the fundamental features of larger laboratory models is designed for field exploration for bauxite and related materials. The apparatus, requiring only a source of electrical power, combines portability with ease of operation and rapid analysis. The portable unit is suitable for quantitative work and has been successfully applied in bauxite exploration on the island of Hispaniola.

1. Internodes of young seedlings of Pinto bean (Phaseolus vulgaris L.), grown under fluorescent lights, elongated to about three or more times their normal length in response to low radiant energies of unfiltered incandescent-filament light applied at the close of daily high-energy fluorescent-light periods. The lengthening response was due to the far-red radiant energy of the supplemental light and was completely and repeatedly reversible with red. Maximum lengthening occurred when the plants received cycles of about 4 hours of light and 20 hours of dark. Plants that received no daily high-energy period of light did not elongate in response to far-red treatments unless given sugar solution through their severed hypocotyls. 2. The lengthening response was found to result from the action of a photoreversible pigment which also controls flowering, seed germination, and certain other photoregulated phenomena. Experiments with bean internode elongation show that this pigment is present and functioning in the ...

The method of electron diffraction is used for determining the C–O–C valence angle (α) in 4,4′ diiododiphenyl ether [(C6H4I)2O] and the molecular structures of phosphorus (P4) and arsenic (As4). The electron diffraction photographs were analyzed by four different methods as follows: (1) Visual measurements, (2) measurements of densitometer records, (3) conversion of densitometer records into relative intensity curves, (4) comparison of transformed intensity curves obtained by multiplying the intensity of scattering by [(1/λ) sin θ/2]2 which produces prominent maxima for measurement. The valence angle α was found to be 118±3° for 4,4′ diiododiphenyl ether, definitely greater than the oxygen valence angle found for simpler types of molecules. Phosphorus and arsenic molecules were found to have a regular tetrahedral structure within the limits of experimental error, the atomic separations being 2.21A and 2.44A, respectively, [methods (1) and (2) were used for the case of arsenic]. The minimum atomic distances as found by crystal structure analysis for phosphorus and arsenic are approximately the same as the atomic separations obtained for the gas molecules, showing in addition that these distances do not change greatly when the bond angle decreases from 100° to 60°.

1. Mimosa pudica L. pinnae close in darkness when phytochrome is predominantly in the far-red-absorbing form (Pfr) and remain open when Pfr is low [6]. The leaflets remain open, however, in normal light periods irrespective of the form of phytochrome. Pinnae, after closing in darkness, regularly reopen in light. 2. An action spectrum for the opening response shows maxima for effectiveness near 710 and 480 nm. This action spectrum is similar to that for a high-energy response affecting morphogenesis in many plants. 3. Dropping of the petiole of M. pudica can be photostimulated by irradiation of the primary pulvinus after holding the plants in darkness [4]. 4. The photostimulation of the primary pulvinus is effective only at wavelengths less than 520 nm. Wave bands in the region of 400 to 470 nm are about equally effective. 5. These photoresponses of M. pudica are related to current discussion about the nature of the high-energy and phytochrome photomorphogenic reactions.

1. The purposes of this investigation were to obtain quantitative data on the photoreactions that prevent flowering of short-day plants, from which an action spectrum relating wave length to photoperiodic effectiveness of light could be derived, and to draw such inferences concerning the nature of the photoreactions as the action spectrum would permit. 2. Experiments designed to give the action spectrum made use of a specially designed prism spectrograph having a dispersion of 15 A. per cm. at 5000 A. At this wave length and with an effective slit width of 100 A. the energy was about 3000 ergs per sq. cm. per second with the slit illuminated by a carbon arc operated at 12 kw. input. 3. Plants investigated were soybean, Soja max (L.) Piper var. Biloxi, and cocklebur, Xanthium saccharatum Wallr. To facilitate irradiation, the foliar surface of the plants of each species at the beginning of an experiment was reduced to a single leaflet or leaf, respectively. 4. The experimental treatment was based on the fac...

Rotational analyses of ${\mathrm{S}}_{2}$ bands as carried out by various workers have led to the following values for the nuclear separation; 1.60A, 1.84A, 1.73A, and 1.93A. In the present work this distance was determined by electron diffraction from ${\mathrm{S}}_{2}$ vapor at 800\ifmmode^\circ\else\textdegree\fi{}C and was found to be 1.92\ifmmode\pm\else\textpm\fi{}0.03A. This value is based upon the measured relative intensities of scattering in the region of the third maximum, $(\frac{1}{\ensuremath{\lambda}})sin\frac{1}{2}\ensuremath{\theta}$ from 0.70 to 1.0, and upon visual measurements on the fourth, fifth and sixth diffraction maxima. When the temperature of sulphur vapor is decreased appreciably below 800\ifmmode^\circ\else\textdegree\fi{}C its electron diffraction pattern shows the presence of higher molecular types. The results obtained can be explained on the basis of ${\mathrm{S}}_{2+n}$ molecules where $n=1,2,3\ensuremath{\cdots}$ with a S---S---S valence angle of about 100\ifmmode^\circ\else\textdegree\fi{} and a S---S distance, between closest neighbors, of ca. 2.1A. These values are in agreement with those found for the symmetrical puckered ring-shaped ${\mathrm{S}}_{8}$ molecule present in crystalline sulphur.

Dark-germinating seeds of Ace and Porte tomato varieties can be inhibited by far-red radiation. Germination of inhibited seed is promoted by red radiation and in turn is reversed by far-red radiati...

Crystals of some micas and related compounds having "layer" lattices show pronounced continuous scattering of x-rays together with normal interference maxima. Continuous scattering is explained as arising from destruction of the lattice periodicity normal to the perfect cleavage of these types of substances. This is a result of translation of some layers along the $b$ axis and parallel to the cleavage by $\frac{n{b}_{0}}{3}$, where ${b}_{0}$ is the unique lattice periodicity and $n$ is an integer. Various crystals differ in their degree of randomness and four general types are recognized; (1) no irregularity, (2) most elements of the crystal mosaic have a few irregular layers, (3) some elements have a regular sequence of layers while others have many irregular layers, (4) all elements have many irregular layers which leads to a small pseudo unit of structure. The phenomenon is illustrated by reproductions of photographs.