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Notes: Summary The uptake of35SO4 −− by aerial roots ofEpidendrum was investigated using microautoradiographic techniques. During a 30 min application to the velamen the isotope is transported through the cortex and the passage cells of the endodermis and pericycle and accumulated into the protoxylem vessels. The results are discussed with regard to the general problem of ion uptake into the xylem.

Notes: Summary 1. Micro-autoradiographic investigations using 35SO 4 -- showed that in Nepenthes the roofed glands at the bottom of the pitcher and, in the case of Dionaea, the glands of the clap-traps are the preferred loci of resorption. 2. The resorption in Nepenthes-pitchers is specific. L-Alanine, PO 4 3- and SO 4 2- are resorbed with different velocity. For the velocities of resorption the following sequence was observed: L-Alanine〉PO 4 3- 〉SO 4 2- . 3. The velocity of the resorption of phosphate by the Nepenthes-pitcher was investigated in relation to the phosphate concentration of the solution applied. The graph obtained from the measured values corresponds in its initial trend with the theoretically expected curve on the assumption that the Michaelis-Mentenrelation is valid for the effect in question. However, in the range of physiological concentrations no saturation was observed.

Notes: Summary The transport of chloride in isolated tissue from Nepenthes pitchers was investigated using 36Cl-, an Aminco-Cotlove chloride-titrator for the determinations of Cl- concentrations, and KCN and AsO 4 - -as metabolic inhibitors. The tissue was brought in contact with different experimental solutions (=medium). The surface corresponding to the outside of the pitchers was cut with a razor blade to remove the cutinized epidermal layer. At this surface the Cl- uptake from the medium is a metabolic process which depends on the Cl--concentration of the medium in a manner that corresponds to the Michaelis-Menten kinetics. The Michaelis-constant of this transport step was 3×10-2M. The Cl--efflux into the medium, however, is a passive process. The opposite surface of the tissue slices (corresponding to the inside of the pitchers) carries the glands. The chloride secretion taking place here is also dependent on metabolism. In vitro it occurs even when a high gradient of chloride concentration has been set up between the medium and the solution which is in contact with the glands. In vivo the Cl--concentration of the pitcher fluid and the amount of Cl- per gram of tissue water are almost equal. The rôle of chloride in the physiology of Nepenthes is still under investigation, A correlation between the chloride content of the pitcher fluid and its enzymatic activity (Casein-test), however, could already be demonstrated.

Notes: Summary The secretion of 36Cl- by tissue isolated from Nepenthes pitchers was investigated with microautoradiographic techniques. The tissue was transferred into ether at-30°C or embedded in the vacuum, following procedures described earlier (Lüttge and Weigl, 1965). The microautoradiographs which we obtained after application of 1–10 mM chloride solutions to the surface corresponding to the outside of the pitchers showed a high labelling of the gland cells, the cell borders in the mesophyll (i.e. the cell walls including the thin plasmatic layers), plasmatic particles and the conductive tissue. The gland cells have only very small vacuoles and are densely filled with cytoplasm. The grain counts show that the radioactivity in the parts of the tissue which are rich in cytoplasm (glands, cell borders, plasmatic particles) did not differ within the statistical error. The activity of the vacuoles, however, was much less. These findings are discussed in the light of Arisz' theory of symplasmatic transport. However, an artificial transfer of the radioactivity contained in the large vacuoles of the mesophyll cells to the cytoplasm during the preparation can not be entirely excluded.

Notes: Summary Differences in the ultrastructure of the leaf cells of young and old branches of Mnium are demonstrated. The appearance of the cytoplasm and the endoplasmatic reticulum membranes differs with the age of the leaves. In the young leaves numerous vesicles are found within the tonoplast. Quite pronounced are changes in plastid structure. Compared with those of the young leaves the chloroplasts of the old leaf cells have many more thylacoid membranes which form large grana. The changes in ultrastructure coincide with differences in transport phenomena reported earlier. A few speculations on the possible significance of this correlation are presented.

Notes: Summary Inhibition of internodial growth of pea seedlings by light is compensated for by increased growth of leaves. At a given time the sum of fresh weight of internodes plus the product of fresh weight of leaves times a certain factor is constant in darkness or with different periods of light. This correlation may reflect a competition of internodes and leaves for materials delivered at a lightindependent rate from the cotyledons. This hypothesis was tested by immersing roots of pea seedlings into 86Rb labelled K-solutions for one day in darkness, removing the plants from the solutions, exposing the seedlings to near or far red light and measuring the radioactivity and fresh weights of leaves and internodes separately. Radioactivity and fresh-weight were both dependent on phytochrome; i.e. inhibition of ion uptake and of growth in internodes and promotion of both processes in leaves by near red light as compared to dark or far red controls are mediated by phytochrome. Short time experiments of ion uptake by the roots show that K transport into the shoot organs is promoted by light after a lag phase of somewhat more than one hour. This interval corresponds well to the lag phase of the light induced growth inhibition of internodes. Seedlings deprived of cotyledons and roots grow well in water but exhibit no difference in growth rate of leaves and internodes in light and darkness. Light dependence is restored if the seedlings are submersed in approximately 3% sucrose solutions. This result seems to indicate that the influence of light on growth rates of leaves and internodes is dependent on the uptake of material by the cell. It seems possible that in the etiolated pea seedling light promotes growth of leaves by promoting uptake and hampers growth of internodes by inhibiting uptake of essential growth material delivered from the cotyledons.

Notes: Summary Methods of quantitative microautoradiography are described. The kinetics of ion uptake into the cytoplasm (including the plastids and other organelles) were investigated by means of microautoradiography and electron probe X-ray microanalyser. The results of microautoradiography show that under our experimental conditions at the end of the experiments the cytoplasm contains much more label per unit of volume than the vacuoles. The kinetics of this filling — up of the cytoplasm correspond to the system-1 isotherm of ion uptake. It must be concluded from the literature that system-1 reflects the process filling up the cytoplasm (=transport through the plasmalemma). The kinetic data reported here describe directly the actual filling — up of the cytoplasmic phase. For this reason the coincidence of kinetic features such as the hyperbolic shape of the rate versus concentration curves in both instances is of interest for the general model of ion uptake into cells of higher plants. The time course of the filling of the cytoplasm is dependent on the external concentration. Similar kinetic data are obtained with the electron probe X-ray microanalyser. The usefulness of a parallel application of microautoradiographic and electron probe X-ray microanalyser techniques in kinetic studies of transport is discussed.

Notes: Summary Isotherms of K(Rb)-, Cl- and SO4-uptake by young and old branches of the moss Mnium cuspidatum were investigated. Old moss gametophytes from the 1966 vegetation period were collected in the forests surrounding Darmstadt from February to mid-April 1967 and from the 1967 season in late September 1967. Young plants were sampled from mid-April to the end of May 1967 and they were also grown by water culture of old plants. Both young and old branches have hyperbolic isotherms of ion uptake in the low concentration range (0–0.5 mM) (Fig. 1–3), which slightly differ in K mand V max (Table). Isotherms in the high range (1–10 mM), however, are drastically different, changing from linear or exponential with young moss branches to hyperbolic with old gametophytes (Figs. 1–3). The linear or exponential high-range isotherm obtained with young moss plants is compared with other examples reported in the literature (Fig. 4). As the leaflets of the moss plants, which constitute 2/3 of the fresh weight of the material used in the experiments, have well developed vacuoles, the correlation between hyperbolic isotherms and vacuolation does not apply here (Fig. 4a, Torii and Laties, 1966). The change in shape of the high-range moss isotherm with age resembles the change from exponential to hyperbolic kinetics in isolated potato discs during washing (Fig. 4b, Laties, Macdonald and Dainty, 1964). The events triggered by isolation of potato discs from the interior of the tuber may be similar to the changes in the moss material under the control of the terminal bud, which is only active in the young branches. The suggested influence of the active terminal bud of young moss plants on the ion absorption process of cells in the tissue may be related to effects of growth substances on translocation reported in the literature and may point to a direct effect of these regulatory systems on membrane function. In this respect the comparison of corn root stele and cortex is of interest. Isolated steles, both freshly isolated and after washing, have exponential isotherms in the high range (Fig. 4c), whereas cortex displays a hyperbolic isotherm which changes little with ageing (Lüttge and Laties, 1967). In contrast to the case in potato and moss materials, this phenomenon is not simply due to ageing but involves morphogenetic differences. Temperature is another factor which influences the shape of the high range isotherm. All examples discussed so far refer to experiments at room temperature. At low temperatures high-range isotherms for proximal root tissue or aged potato discs have an exponential shape (Torii and Laties, 1966; Laties, Macdonald and Dainty, 1964). It thus appears that the exponential isotherm of young moss branches indicates that as in freshly isolated potato discs or in corn root stele the metabolic high-range uptake system is not developed.

Notes: Summary The fine structure of the salt-glands in the leaf epidermis ofLimonium vulgare was investigated. The glands are very similar to those ofStatice Gmelini (Ruhland, 1915). The main results were as follows: 1. All gland cells have dense cytoplasma, large nuclei, numerous mitochondria and sometimes protuberances of the cell wall. 2. The passage spots in the cutinized “border cap” between the outer “cup cells” and the “collecting cells” show numerous plasmodesmata. 3. The cell wall protuberances in the gland cells often grow out in connection with plasmodesmata and not seldom include parts of the cytoplasm. 4. In the inner “cup cells” the mitochondria sometimes show paracrystalline inclusions. 5. In the gland cells (with the exception of the outer “cup cells”) electron-dense belts are often formed. 6. The “border caps” under the secretion-pores have no direct contact with the protoplast of the secretion cells but are attached to the outer cell wall.