The processes of dimethylsulfoniopropionate (DMSP) uptake and dirnethylsulfide (DMS) production from DMSP were investigated using a marine bacterium isolated from Sargasso Sea water. Uptake of DMSP into the cell preceded cleavage to form DMS, indicating an intracellular location for the DMSP lyase. The rate of DMS production accelerated rapidly during the timecourse of DMSP cleavage, independent of cell growth; this increase in rate was suppressed in the presence of 500 pM chloramphenicol, consistent with induction of the DMSP lyase. Additionally, preincubation with acrylic acid, the putative byproduct of the cleavage, as well as with DMSP, stimulated the initial rate of DMS production. Two determinations of the K,, V,,, values for DMSP uptake in induced cells yielded 190 nM, 1.3 fmol cell-' h-' and 105 nM, 3.2 fmol cell-' h-' A single determination of these parameters in uninduced cells yielded 280 nM and 1.9 fmol cell-' h-'. The rate of DMS production from DMSP exhibited a sigmoidal dependence on extracellular DMSP concentration.

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Equilibrium isotherms for water have been measured on three samples of Saran charcoal between 10" C and 60" C. The heats of adsorption at very low surface coverage are as high as 15,000 callmole, but for most of the water adsorbed are only slightly greater than the heat of liquefaction. On desorption, there is no hysteresis loop.Water adsorbs more slowly than a hydrocarbon of comparable size. At low relative

A hard, highly porous charcoal has been prepared by the pyrolysis of polyvinylidene chloride. Adsorption isotherms were determined for water, helium, n-pentane and nitrogen. Isosteric heats of adsorption were obtained for nitrogen, and anomalous results were observed below a pressure of 20 microns. Rates of adsorption have been studied for a number of simple hydrocarbons. Large bulky molecules were adsorbed slowly, while linear and planar molecules were adsorbed quickly. Fick's diffusion law was obeyed by those molecules which were adsorbed at measurable rates. The temperature dependence of the rate showed that activated diffusion occurred, and activation energies were calculated. Variations of these energies do not wholly account for the variable rates of adsorption for different molecules, so that steric limitations must play a part.Saran is the generic term for a series of thermoplastic resins derived from vinylidene chloride, which thus have the formula (CHCI),. Pyrolysis drives off hydrogen chloride and yields a form of charcoal. This material was shown by Pierce, Wiley and Smith 1 to be highly porous and to give Langmuir type isotherms with most organic adsorbates. There were indications that the pores in this charcoal were very small ; thus Emmett 2 reported that one specimen adsorbed one-twelfth as much iso-octane as nitrogen. The work described in this paper was chiefly concerned with an investigation of this selective adsorption. EXPERIMENTAL MATERIALSCharcoal.-Pure polyvinylidene chloride was obtained from the Dow Chemical Co. as a powder. It could be readily pressed at 100" C into hard cylinders, using metal moulds and a hydraulic press. This moulded material was heated in a quartz tube in DCICUO, at first at 180" C for several hours which resulted in about 35 % loss of weight, and then the temperature was raised in steps to 700" C, when decomposition was nearly complete as indicated by approximately 74 % loss of weight (calc. for CHCl --f C + HCl, 75-3 % weight loss). The product was a remarkably hard piece of charcoal which, if the heating had not been too rapid, largely retained the shape of the original moulded piece of Saran. Heating the unpressed Saran powder gave a friable mass with different adsorptive properties (see later). Contrary to the experience of Pierce et al., with this Saran it was not necessary to treat the charcoal at 600" C with hydrogen in order to obtain a water isotherm that showed a sharp rise.Helium was obtained by collecting the gas from the boiling liquid. Nitrogen was from a Matheson " prepurified" sample, and was passed over hot copper turnings and through a liquid-air trap. A mass spectrograph analysis showed the sample to be better than 99.9 % pure. n-Pentane was Phillips research grade ; it was washed with H2SO4, NaOH and water, and dried with CaC12 and P2O5.neo-Pentane was Phillips research grade, and was dried with P205. iso-Octane and cyclohexane were washed with concentrated H2SO4 and distilled from cis-and trans-Butenes were Phillips research grade.sodium.