The Distribution of Zinc-65 in Agrostis tenuis sibth. and A. stolonifera L. Tissues4

The distribution of ⁶⁵Zn in zinc-tolerant and copper-tolerantplants of Agrostis spp. from toxic mine-tailings in Enflandand Wales was compared with zinc distribution in non-tolerantplants. Isotope was applied in culture solution in which theplants were growing. No differences could be demonstrated betweenthe plants were growing. No differences could be demonstratedbetween the plants by whole-plant radioautography, or by zincanalyses of the tops. Root/shoot ratios calculated from specificactivity values varied with population, the non-tolerant plantshaving the lowest and the zinc-tolerant plants the highest ratio.After solvent (80 per cent ethanol and water) extractions, theroot residue of zinc-tolerant plants contained a higher percentageof ⁶⁵Zn than that of non-tolerant plants. Chemical fractionationof the roots revealed that the main high difference was thatthe amount of ⁶⁵Zn in the pectate extract of the cell wall washigh in zinc-tolerant plants and low in non-tolerant plants.The ⁶⁵Zn distribution in the copper-tolerant plants was similarto that in the non-tolerant plants, indicating that the tolerancemechanisms for the elements are different. Soluble protein andRNA preparations were made but they contained low levels of⁶⁵Zn. An exception was the relatively high value for RNA fromzinc-tolerant A. stolonifera shoots. An anionic complex of ⁶⁵Znin the soluble fraction was investigated. This complex accountedfor most of the radioactivity in A. tennis extracts of shootsbut the concentration of the complex was low in A. stoloniferashoots, and in root extracts of all plants examined.     

THE RELATIONSHIP BETWEEN CONSUMER PREFERENCES AND TRAINED PANEL RESPONSES

Eight samples of dried tomato soups were profiled by a trained panel, who also provided ratings of overall liking and liking for particular attributes on relative-to-ideal rating scales. A consumer panel tested a subset of four of the soups in home trials, assessing them for overall liking and for particular attributes on either hedonic or relative-to-ideal rating scales. The pattern of overall preferences differed between the trained and untrained panelists, demonstrating the inappropriateness of using trained panelists to provide measures of preference or acceptance. The conclusions regarding consumer preferences would differ depending on which rating scale was used; these differences disappeared when the relative-to-ideal ratings were converted into values of the same form as the hedonic ratings. The overall liking was best predicted by flavor rather than color or thickness. A principal components analysis (PCA) of the profile data compared well with a plot based on the trained panel preference data using MDPREF. The preference data were also fitted to the PCA dimensions using the PREMAP vector model, which gave a good fit for only six of the 15 trained panelists; the PREMAP ideal point model failed to show a better fit. In order to test these models adequately more than eight samples would need to be tested.     

CORRIGENDUM

Vol. II, N. S. No. 5 (January 1938), article by A. H. K. PETRIEand j . G. WOOD. In Table VII, p. 53, all values of the coefficientsof A²_R and A²_T should be preceded by minus signs.     

Phosphate fluxes, compartmentation and vacuolar speciation in root cortex cells of intact Agrostis capillaris seedlings: effect of non-toxic levels of aluminium

From compartmental analysis of ³²P elution measurements, concentrationsand fluxes of orthophosphate were estimated for root corticalcells of intact seedlings of the indigenous grass Agrostis capillarisL. cv. Highland when in complete nutrient solution containing10 mmol m^–3 or 100 mmol m^–3 phosphate with or without3.7 and 37 mmol m^–3 Al, respectively, during loading andelution. When plotted as counts min^–1 remaining in thetissue as a function of time, the data failed to meet the criteriafor first order kinetics. Transformation of the data to meetthe kinetic criteria gave corrected values for compartmentalconcentrations and fluxes of phosphate, and estimates of theotherwise unresolved slowly exchanging compartment within thevacuole considered to be the cause of the discrepancy in fluxanalysis. In the control, the discrepancy was considered dueto sequestration of phosphate with Ca in the vacuole and a small,but not significant, increase in sequestered P occurred in thepresence of Al, the presence of which was confirmed by X-raymicroanalysis. A chemical speciation model was used to demonstrate,for various values of pH and carboxylic acid concentration,the possibility that phosphate was precipitated in root cellvacuoles as Ca and Al phosphates (hydroxy-apatite and variscite).The ecological significance of the ability of A. capillarisplants to make efficient use of scarce P resources by minimizingthe sequestration of P by Al in vacuoles, compared with Loliumperenne, was recognized. Key words: Phosphate sequestration, phosphate use efficiency, X-ray microanalysis, super-saturation     

ASSESSMENT OF BIVALVE INTRACELLULAR DIGESTION BASED ON DIRECT MEASUREMENTS

Two methods of studying intracellular digestive state in bivalvemolluscs, (1) the subjective tubule grading technique and (2)an alternative method based on measurements of digestive tubuleand luminal widths, were compared using data from a starvation/feedingexperiment on the quahog, Mercenaria mercenaria (L.). Measurementsof digestive cell heights or lumen widths could not be directlycompared due to differences in tubule widths within and betweenindividuals (range = 56.6 to 77.4 µm; X = 63.0; SD 4.8(µm) which were unrelated to quahog length. Instead, themean proportion of the tubule width (MPTW) covered by digestivecell cytoplasm was used for comparisons between samples of animals.MPTW covaried directly with the subjectively established proportionof Type II tubules (r = 0.882). The inclusion of data from obliquesections of digestive tubules did not unduly affect statisticalresults . Of 4 sampling schemes compared, a systematic samplingscheme in which measurements were made on only one digestivegland tubule within an area containing a cluster of similartubule types, was shown to be best. ¹Contribution No. 105, Marine Science Institute, NortheasternUniversity, Nahant, MA., 01908 ²Current address: New England Aquarium, Central Wharf, Boston,MA, 02110 USA (Received 28 September 1981;     

Plankton community respiration in Bransfield Strait (Antarctic Ocean) during austral spring

Community respiration (R) was determined in Bransfield Straitfrom oxygen changes in water samples incubated in borosilicatebottles maintained at in situ temperature. The respiratory electrontransport system (ETS) activity of seawater communities wasalso measured from the same samples. Both data sets were relatedby the regression equation: log R (mg O₂ m^–3 day^–1)=0.462+0.730xlogETS activity mg O₂ m^–3 day^–1) (r=0.80, n=23). Fromthis equation and 37 ETS activity depth profiles, we calculatedthe integrated (0–100 m) community respiration as beingin the range 1.2–4.5 g O₂ m^–2 day^–1 (mean=2.2).These values do not differ significantly from other publishedresults for the Arctic and Antarctic Oceans. Assuming a respiratoryquotient of unity, the areal respiration ranges between 0.45and 1.69 g C m^–2 day^–1 (mean=0.8). This would representan important sink for the primary production reported for BransStrait. The spatial distribution of community respiration showedhigher values associated with the warmer and phytoplankton-richwaters outflowing from Gerlache Strait into Bransfield Strait,and with the front that separates Bellingshausen Sea watersfrom Weddell Sea waters. We suggest that this pattern of distributionmay be related to the transport of organic matter by the BransfieldCurrent along the front.     

Uptake, transport and stability of [2-14C] abscisic acid in cucumber following foliar application

The uptake, transport and stability of ABA after foliar applicationto cucumber plants was studied using [2-¹⁴C] ABA. ABA uptakethrough uninjured epidermis of cucumber leaves appeared to bevery slow compared with the uptake through abraded leaves. Transportof [2-¹⁴C] ABA in the same system was also found to be veryslow. No metabolic changes in the absorbed [2-¹⁴C] ABA weredetected 24 hr after its application as checked by TLC and GLCtechniques. These results are compared and discussed in relationto previous reports. ¹The Irene and David Schwartz Professor of Plant Genetics (Received April 26, 1976; )     

REDUCING THE NOISE CONTAINED IN DESCRIPTIVE SENSORY DATA

A data reduction protocol was designed to minimize distortion inherent in sensory data. Following removal of nonexistent attributes and treatment levels, extreme value analysis and distribution comparisons combined with graphical respresentations, facilitated elimination of inconsistent (with respect to overall consensus) panelists. Application of a calibration factor showed superresponsive panelists (those with intensity values consistently higher than other panelists) were among the most accurate and thus were retained in spite of their tendency to produce extreme value data. Panelists that consistently produced a narrow variance around the overall mean and rarely produced extreme values were classified as noncomittal and removed. Analysis of variance calls for a split plot design; blocks (sessions) and treatments in main plot, and panelists in subplot. In general, the subplot can be ignored. These methods are suggested for evaluating panelists' training needs; and for eliminating data that distorts the statistical analysis.     

Acid-base regulation after maximal exercise testing in late gestation

Kemp, Justin G., Felicia A. Greer, and Larry A. Wolfe.Acid-base regulation after maximal exercise testing in late gestation. J. Appl. Physiol. 83(2):644-651, 1997.This study employed Stewart's physicochemicalapproach to quantify the effects of pregnancy and strenuous exercise onthe independent determinants of plasmaH⁺ concentration([H⁺]). Subjects werenine physically active pregnant women [mean gestational age = 33 ± 1 (SE) wk] and 14 age-matched nonpregnant controls. Venousblood samples and respiratory data were obtained at rest and during 15 min of recovery from a maximal cycle ergometer test that involved 20 W/min increases in work rate to exhaustion. Mean values for[H⁺],PCO₂, and total protein increased,whereas those for bicarbonate concentration([HCO₃]) and the strong ion difference ([SID]) decreased in the transition fromrest to maximal exercise within both groups. At rest and throughoutpostexercise recovery, the pregnant group exhibited significantly lowermean values for PCO₂,[HCO₃], and total protein,whereas [SID] was significantly lower at rest and early recovery from exercise.[H⁺] was also lower atall sampling times in the pregnant group, but this effect wassignificant only at rest. Our results support the hypothesis thatreduced PCO₂ and weak acidconcentration are important mechanisms to regulate plasma[H⁺] and to maintain aless acidic plasma environment at rest and after exercise in lategestation compared with the nonpregnant state. These effects areestablished in the resting state and appear to be maintained aftermaximal exertion.

     

Soil microbial community and bacterial functional diversity at Machu Picchu, King George Island, Antarctica

The objective of this study was to evaluate the potential contribution of the soil microbial community in the vicinity of two plant covers, Sanionia uncinata and Deschampsia antarctica, at Machu Picchu Station, King George Island, Antarctica. Soil samples were collected at the study site during the southern (pole) summer period from 0-5 cm and 5-10 cm depths, for chemical and biological analyses. Soil microbial biomass reached a maximal value of 144 µg g^-1 in soil samples taken from under the S. uncinata upper layer plant. qCO₂ ranged from 167 to 239 µg CO₂^.mgC_mic^.h^-1 at the 0-5 and 5-10 cm depths, respectively. CO₂ evolution showed values of 54.3 mg^.m^-2 h^-1 beneath plant cover and 55.9 mg^.m^-2 h^-1 in the open space. CO₂ evolved by substrate induced respiration in the soil samples taken under the plant cover in the summer period, oscillated between 0.25 and 4.78 µg CO₂ g^-1 h^-1. The data obtained from this short study may provide evidence that both activity and the composition and substrate utilization of the microbial community appear to change substantially across the moisture level and sample location.     

Investigations of the {delta}13C Pattern in Leaves of Fagus sylvatica L.

The natural abundance of ¹³C in different parts of beech (Fagussylvatica L.) leaves was analysed. Values for leaf ribs wereconsistently higher than those for intercostal tissue. Similardifferences occur between petiole and stem, with petiole beingless negative. The pattern of results is the same, independentof the position in the tree. However, the absolute values differby up to 6%. from the bottom to the top of the tree. Valuesof ¹³C are in the range of – 29 to – 32%. for thelower leaf strata; while values between – 24 and –26%. have been measured for the top of the tree. Absolute ¹³Cvalues of the whole tissue and cellulose differ by about 2%.,but relative ¹³C trends are almost identical. However, ¹³C trendsare not identical for different leaf parts. A comparison ofcellulose and whole tissue ¹³C data makes it unlikely that the¹³C variations are primarily due to different compositions ofchemical compounds. No fractionation seems to exist betweenleaf and wood cellulose. Tissue from different areas of a leafrevealed identical carbon isotope compositions. Key words: Carbon isotope ratio, Fagus sylvatica L., beech leaves     

The Incorporation of 14C into the Protein of Particles Isolated from Plant Cells

The incorporation of ¹⁴C from labelled fructose, succinate,urea, and proline, by particulate preparations from dormantand tissue-cultured carrot cells, is examined. It is shown that¹⁴C is incorporated readily from proline, and less readily fromfructose. No significant incorporation occurs from succinateor urea. No differences are noted between the two kinds of preparation.It is concluded that the incorporation of ¹⁴C does not dependon prior transfer of the label to carbon dioxide followed byfixation of carbon dioxide, since the particles do not incorporate¹⁴C from supplied carbon dioxide. Incorporation of ¹⁴C by various fractions of dormant carrottissue is examined, and it is established that the greatestincorporation per mg. nitrogen occurs in particles isolatedat 10,000 g. A total cell homogenate fails completely to incorporate¹⁴C from proline into protein, and this may be due to suppressionof the activity of the particles by a constituent of the supernatantliquid. The presence of coconut milk reduces the incorporationof ¹⁴C from proline by particles sedimented at 10,000 g, andaddition of a protein hydrolysate reduces it further. Hydroxy-prolinedoes not appear to compete with proline for incorporation, andin this respect the paniculate preparations contrast with wholecells. Particles from carrot tissue are shown to be more active inincorporating ¹⁴C from proline than are particles extractedby the same procedure from red beet roots, potato tubers, andskunk cabbage inflorescences. They are, however, considerablyless active than a mitochondrial preparation from rat liver. It is demonstrated by paper chromatography that the bulk ofthe ¹⁴C incorporated in the particles from carrot cells remainsin proline and there is little or no conversion of proline tohydroxyproline in the preparations. The nature of the particlesemployed in this investigation is discussed, and their metabolismconsidered, in relation to the structure and activity of wholecells.     

Dark uptake of inorganic14C in oligotrophic oceanic waters

Dark uptake of inorganic ¹⁴C by offshore plankton was measuredat two depths at 36 stations in the Atlantic Ocean from 52°Sto 26°N, mainly along 30°W. The samples were incubatedfor 2 h with and without inhibition of biological activity withHgCl₂. In addition, six time course experiments were performed.The mean dark uptake rate varied from 0.68 to 4.82 (µmolC m^–3 h^–1 over the transect and showed a significantpositive relationship with chlorophyll a. The dark uptake wasusually >5% of the maximum photosynthetic capacity (P^m),and higher values relative to P^m were associated with low valuesof P_m and not with high absolute dark values. A linear relationshipbetween dark uptake and P_m was found with a background value(y-axis intercept) of 0.51 (µmol C m^–3 h^–1and a slope of 0.77% of P^m. A major fraction of the dark signal,66–80% of the total signal, persisted in bottles treatedwith HgCl2, indicating that most of the dark signal was independentof biological activity. Time course experiments showed a lineardark uptake with time for the first hours, whereafter the uptakeceased. At stations with low concentrations of inorganic nitrogen[>1 (µmol (NH₄⁺+NO₃^–)], a second stage was observedafter 3–8 h, probably due to an increase in bacterialactivity. The results suggest three mechanisms for the darkvalue in short-term incubations in oligotrophic waters. A backgroundvalue independent of biomass and incubation time which was thedominant part of the dark signal in samples with very low phytoplanktonbiomass (>0.3 p-g Chi a 1"). Another important part was residualsof ¹⁴C associated with plankton, probably adsorbed to compoundsinside the cells. This fraction was dominant in short-term incubationsat chlorophyll concentrations >0.3 p.g Chi a H. Active uptakeby living cells (total minus ‘HgCl2 uptake‘) wasonly a minor part of the dark signal in short-term incubations,but dominated at longer incubation time (>3–9 h), probablydriven by an increase in bacterial activity. A significant enhancementof the non-photosynthetic uptake of ¹⁴C was observed in light,probably associated with a carbon-concentrating mechanism inphytoplankton or light stimulation of ß-carboxylationactivity. The results strongly suggest that dark values shouldbe subtracted from the light uptake. This correction is particularlyimportant when photosynthetic rates are low, e.g. at low lightor in short-term incubations where a time-zero background becomesa significant part of the total uptake in light. Present address: National Environmental Research Institute,Department of Marine Ecology and Microbiology, Frederiksborgvej399, PO Box 358, DK-4000 Roskilde, Denmark     

Comparison of Four Methods Calculating the Seasonal Pattern of Plant Growth Efficiency of a Kiwifruit Berry

Four methods of determining the substrate requirements for synthesisof a kiwifruit [Actinidia deliciosa (A. Chev.) C. F. Liang etA. R. Ferguson var. deliciosa cv. Hayward] berry were comparedusing data derived from common kiwifruit berry samples collectedfrom anthesis to fruit maturity. The four methods were basedon fruit proximal analysis, elemental analysis, heats of combustion,or tissue carbon content. All methods gave similar patternsof seasonal costs and values of final cost to the plant (mean1.21 g glucose g^–1 season^–1) but there was lessagreement for growth respiration (mean 0.147 g glucose g^–1season^–1). This is the first time that a continuous recordof growth cost over the course of development has been presented,and the trends in seasonal cost reflect the uptake into andsynthesis of the different biochemical constituents in the fruit.The differences between the results of each method reflect theunderlying assumptions used in their development. It appearsfrom this work that the method of McDermitt and Loomis (1981),utilizing elemental analyses, is most preferred. Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson var deliciosa cv Haywood, kiwifruit, true growth yield, plant growth efficiency, production value, glucose value, bioenergetic cost     

Characterization of ATPases Associated with Various Cellular Membranes Isolated from Etiolated Hypocotyls of Vigna radiata (L.) Wilczek

Cellular membrane fractions, including endoplasmic reticum (ER),Golgi-enriched membrane, plasma membrane and tonoplasts, wereisolated from Vigna radiata seedlings. Each of these membranefractions was associated with specific ATPases which were highlydependent on Mg²⁺. ATPases of ER, Golgi-enriched membrane andplasma membrane were sensitive to vanadate but the tonoplastATPase was not. ATPases were mostly dependent on Cl¹, but aslight stimulation by K⁺ was observed in the case of ATPasesof Golgi-enriched membrane and plasma membrane. KNO₃ inhibitedtonoplast ATPase but stimulated the other ATPases. ER ATPasecan be distinguished from other ATPases by the following characteristics:specific inhibition by KNO₂ and Triton X-100, stimulation bylow concentrations of diethylstilbestrol and 4,4'-diisothiocyanostilbene-2,2'-disulfonicacid, and high sensitivity to heat. The ATPases showed typicalMichaelis-Menten kinetics and had K_m values of 0.5 to 0.6 ITIMMg²⁺-ATP for ER, Golgienriched-membrane and tonoplast ATPases,and 2.27 msi Mg²⁺-ATP for plasma membrane ATPase. ATPases ofGolgi-enriched membranes and plasma membranes had similar properties,but they were still distinguishable by the differences in theirK_m values and their responses to Triton X-100. Based on theseresults, it is postulated that each cellular membrane is associatedwith a specific ATPase in cells of V. radiata. ¹Contribution No. 3171 from the Institute of Low TemperatureScience. (Received April 22, 1988; Accepted September 28, 1988)     

A Study of the Exudation of Excised Maize Roots after Removal of the Epidermis and Outer Cortex

The fluid exudation rates and the ionic composition of the exudatesof isolated maize roots were compared with those of similarroots from which the epidermal and outer cortical cells hadbeen removed. The results indicate that in low ionic strengthmedia the salt fluxes into the exudation stream are severaltimes larger in the control than in the treated roots. As theionic strength of the bathing medium increases to 10 mM KClor greater, the salt fluxes become equal. A mechanism to accountfor this behaviour is discussed. The values of L_p, the hydraulic conductivity of the roots toradial water flow, are 0.26 x 10^–6 cm sec^–1 atm^–1for treated and 0.14 x 10^–6 cm sec^–1 atm^–1for control roots, but a statistical technicality precludeda significance test on this apparent difference. The kinetics of tritiated water exchange from external mediumto the exudation fluid in both control and treated roots werenot significantly different. The entry of labelled water seemsto be achieved by the fluid exudation rate in both cases; thusthe barrier to water movement to the exudate compartment remainsintact after removal of the epidermis.     

A Comparison of the Methods of X-ray Microanalysis, Compartmental Analysis and Longitudional Ion Profiles to Estimate Cytoplasmic Ion Concentrations in Two Maize Varieties

Hajibagheri, M. A., Flowers, T. J., Collins, J. C. and Yeo,A. R. 1988. A comparison of the methods of X-ray microanalysis,compartmental analysis and longitudinal ion profiles to estimatecytoplasnuc ion concentrations in two maize varieties.—J.exp. Bot. 39: 279-290. The ion content of compartments within plant root cells hasbeen studied by three different methods; flux analysis usingradioactive isotopes, longitudinal ion profiles and X-ray microanalysis.The data provide estimates of the concentrations of K⁺ and CI^–in the cytoplasm of roots of culture solution and salt grownmaize by three independent methods. In the cultivar LG₁₁ grown in 50 mol m^–3 NaCl X-ray microanalysis,compartmental analysis and longitudinal profiles yielded approximatelyagreeing values for cytoplasmic K⁺ of 90, 70 and 62 mol m^–33of tissue volume respectively. However, the methods disagreedon cytoplasmic Cl^– where the value obtained by compartmentalanalysis was about four times that from X-ray microanalysisand longitudinal profiles. Possible reasons for this are discussed. Key words: X-ray microanalysis, longitudinal ion profiles, compartmental analysis, salt-tolerance.     

Optical emission spectrographic studies on the distribution and accumulation of nanogram amounts of 15N in rice seedlings

An optical emission spectrographic method was used to studythe distribution and accumulation of nanogram quantities of¹⁵N in leaves and roots of individual rice plants. Gaseous nitrogenthat was prepared from plant samples, not weighing more than100 µg, was trapped in an electrodeless tube. The excess¹⁵N was determined by exciting the gas with a high frequencygenerator, then measuring the light intensities of the molecularbandheads at 2977, 2983 and 2989 ?. For leaves that contained4 atom % ¹⁵N the precision obtained was ?1.33%. A comparisonof emission and mass spectrographic ¹⁵N values were obtainedwith a number of second leaves of rice plants that were grownunder similar environmental conditions. The ¹⁵N contents obtainedat a 2 atom % level by the 2 methods were in reasonable agreement. ¹Permanent address: University of Tokyo, Dept. of Agr. Chem.,Japan. ²Permanent address: Argonne National Lab., Argonne, Illinois,U. S. A. (Received April 2, 1969; )     

Effects of Abscisic Acid and Cytoplasmic pH on Potassium and Chloride Efflux in Arabidopsis thaliana Seedlings

The effects of ABA, isobutyric acid (IBA) and nicotine on K⁺and Cl⁺ efflux were studied in Arabidopsis thaliana seedlings,and the role of pH_cyt, and E_m in the regulation of the effluxof these ions was discussed. The data show that treatments withIBA and nicotine influenced in opposite directions the effluxof either K⁺ or Cl^–: K⁺ efflux was increased by nicotineand reduced in the presence of IBA, whereas Cl^– effluxwas stimulated by IBA and decreased by nicotine treatment. Underall the conditions tested ABA induced cytoplasmic acidificationand inhibition of K⁺ and Cl^– net efflux. Experiments aimedto estimate the individual contribution of pH_cyt and E_m in modulatingK^– efflux indicated that, within the range of acidic pH_cytvalues, a regulation of K⁺ efflux was imposed by pH_cyt on thecontrol exerted by E_m, the efflux being inhibited by lower pH_cytvalues. Conversely, in the alkaline side of pH_cyt K⁺ effluxseemed linked only to the E_m values. These results are consistentwith the hypothesis that the decrease in K⁺ efflux observedin non-stomatal tissues in the presence of ABA may be mediatedby the cytoplasmic acidification induced by the hormone. (Received August 6, 1996; Accepted January 19, 1997)     

Analysis of the Diffusion Symmetry Developed by the Alkaline and Acid Bands which form at the Surface of Chara corallina Cells

The diffusion symmetry developed by the alkaline and aeid bandsof Chara corallina was studied. The alkaline system developeda diffusion pattern which could not be fitted to the equationfor a continuous point-source efflux. However, good correlationwas obtained between experimental data and the diffusion equationfor a hollow sphere. The calculated OH- efflux values, obtainedusing the equation of a continuous spherical-surface source,were checked against the influx values of H₁₄ obtained under the same experimental conditions. IndividualOH– band efflux values ranged from 0.07 to 5.95 pmol s^–1and total cell fluxes of 25 pmol cm^–2 s^–1 for OH^-and H were obtained (in the presence of 0.5 mM NaHCO₃). The acid system developed a cylindrical diffusion pattern, butthis could not be fitted to a mathematical equation. Numericalanalysis will have to be employed to obtain values of H⁺ efflux.