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The neglect of inertia terms and assumption of Poiseuille's flow approximations in describing the motion of a liquid with a free surface in narrow passages are inappropriate for certain motions. This is demonstrated with experiments in which the rates of spontaneous rise of a meniseus in an empty capillary tube, when one end is suddenly contacted with a pool of water, were determined with the aid of a high-speed camera. Glass capillary tubes 266 to 1191 μm in diamter were used in the vertical and horizontal orientations. The results indicate that the mean rise velocity falls steadily with time in a logarithmic fashion for the horizontal arrangement and linearly for the initial stage of vertical rise. Deviations from theoretical predictions in which the assumptions above are made are significant and not similar for the different tube sizes. Actual velocity was initially less than predicted. For vertical rise, the velocity after a while exceeds the prediction at different elapsed times for each tube size. It is suggested that, since the highest Reynolds number (

SUMMARY Transpiration rates from and oil content changes in developing oil palm fruits were measured. During fruit development, transpiration rates showed a monotonic increase. The rate of increase was most rapid in the last three weeks of fruit ripening during which practically all mesocarp oil formed. The rate of oil accumulation in the fruits exhibited an exponential followed by a steady increase phase. The phases are proposed to correspond to those for oil droplet precipitation and growth, respectively. The magnitude of the transpiration stream is significant after most of the fruit non-oily solid matter appears formed and before the appearance of oil. Later on, transpiration becomes high enough to account for all the water convected into the fruit with the sugar precursors for oil production. This suggests that xylem flow occurred initially into the fruit before the phloem becomes the primary source for transpired water as oil is produced.

Vessel-length distributions in some trees, shrubs, and a vine have been calculated from measurements of particle penetration and of air-volume flow through the xylem. In shrubs and diffuse-porous species, longest vessels were about 1 m long, but most of them were much shorter, the largest percentage in the 0–10 cm length class. In the two ring-porous species investigated (Quercus rubra and Fraxinus americana), the longest vessels often were as long as the tree's stem, but most of them were much shorter. In the grapevine (Vitis labrusca) which has large-diameter vessels (ca. 300 μm) a small percentage of the vessels was 8 m, but most of them were less than 5 m long. In a given species, lengths of the longest vessel were quite variable, but the distribution of the short lengths was more constant. In general, vessel lengths are correlated with vessel diameters: wide vessels are longer. Even in diffuse-porous species, the slightly narrower latewood vessels are somewhat shorter than the wider early wood vessels. The method is a simplified version of that described by Skene and Balodis, but using a programmable desk calculator. It works best with diffuse-porous species in which vessels are randomly distributed in the stem, and less well in species with wide vessels, because as vessels reach the length of the stem itself, they cannot be randomly distributed.

Mixtures of light hydrocarbons characteristic of liquefied natural gas were boiled on a water surface and the rate of vaporization measured. Heat fluxes were significantly higher than measured for pure liquid methane even when mole fractions ethane, propane, or n -butane were under 0·01. As with pure methane, the rate of vaporization increased during the course of an experiment unless a continuous, thick ice layer formed. Initial liquid water temperatures ranged from 6 to 60°C and spills of LNG from 0·21 to 0·83 g/cm 2 were made. For mixtures of methane and heavier hydrocarbons, where the mole percent of the latter components was greater than 2 per cent, the water surface temperature rapidly dropped to the cryogen temperature, but little change in temperature was noted a few mm below the surface. No significant vapor superheat was noted. Ice formed readily at the interface and the increase in heat flux was explained by postulating a shift from film to nucleate boiling. The boiling mixtures often foamed and photographs taken at the interface revealed that very small vapor bubbles formed early in a run.

Experiments are reported on the spatial distributions of isotopic carbon within the mesophyll of detached leaves of the C3 plant Viciafaba L. fed I4CO2 at different light intensities. Each leaf was isolated in a cuvette and ten artificial stomata provided spatial continuity between the ambient atmosphere (0-03-0-05% v/v CO2) and the mesophyll from the abaxial leaf side. Paradermal leaf layers exhibited spatial profiles of radioactivity which varied with the intensity of incident light in 2 min exposures. At low light, when biochemical kinetics should limit CO2 uptake, sections through palisade cells contained most radioactivity. As the light intensity was increased to approximately 20% of full sunlight, peak radioactivity was observed in the spongy cells near the geometric mid-plane of the mesophyll. The results indicate that diffusion of carbon dioxide within the mesophyll regulated the relative photosynthetic activity of the palisade and spongy cells at incident photosynthetically active light intensities as little as 110 /iE m~2 s~' when CO2 entered only through the lower leaf surface.