THE EFFECT OF HYDROGEN ION CONCENTRATION ON THE PRODUCTION OF CARBON DIOXIDE BY BACILLUS BUTYRICUS AND BACILLUS SUBTILIS

1. The maximum rate of CO₂ production of Bacillus butyricus was found to be at a pH value of 7; of Bacillus subtilis at pH 6.8. If the pH value be raised or lowered there is a progressive decrease in the rate of production of CO₂. 2. Spontaneous recovery follows the addition of alkali to either organism, while addition of acid is followed by recovery only upon addition of an equivalent amount of alkali, and is not complete except when the amount of acid is very small.     

THE ACTIVATION OF STARFISH EGGS BY ACIDS : II. THE ACTION OF SUBSTITUTED BENZOIC ACIDS AND OF BENZOIC AND SALICYLIC ACIDS AS INFLUENCED BY THEIR SALTS.

1. Comparison of the rates of activation of unfertilized starfish eggs in pure solutions of a variety of parthenogenetically effective organic acids (fatty acids, carbonic acid, benzoic and salicylic acids, chloro- and nitrobenzoic acids) shows that solutions which activate the eggs at the same rate, although widely different in molecular concentration, tend to be closely similar in C_H. The dissociation constants of these acids range from 3.2 x 10^–7 to 1.32 x 10^–3. 2. In the case of each of the fourteen acids showing parthenogenetic action the rate of activation (within the favorable range of concentration) proved nearly proportional to the concentration of acid. The estimated C_H of solutions exhibiting an optimum action with exposures of 10 minutes (at 20°) lay typically between 1.1 x 10^–4 M and 2.1 x 10^–4 M (pH = 3.7–3.96), and in most cases between 1.6 x 10^–4 M and 2.1 x 10^–4 M (pH = 3.7–3.8). Formic acid (C_H = 4.2 x 10^–4 M) and o-chlorobenzoic acid (C_H = 3.5 x 10^–4 M) are exceptions; o-nitrobenzoic acid is ineffective, apparently because of slow penetration. 3. Activation is not dependent on the penetration of H ions into the egg from without, as is shown by the effects following the addition of its Na salt to the solution of the activating acid (acetic, benzoic, salicylic). The rate of activation is increased by such addition, to a degree indicating that the parthenogenetically effective component of the external solution is the undissociated free acid. Apparently the undissociated molecules alone penetrate the egg freely. It is assumed that, having penetrated, they dissociate in the interior of the egg, furnishing there the H ions which effect activation. 4. Attention is drawn to certain parallels between the physiological conditions controlling activation in the starfish egg and in the vertebrate respiratory center.     

THE EFFECT OF CYSTINE AND GLYCOCOLL ON THE OXIDATION OF SODIUM LACTATE BY HYDROGEN PEROXIDE

The rate of production of CO₂ from sodium lactate when treated with H₂O₂ may be increased by the addition of a compound containing a sulfhydryl group, i.e. cystine. A small part of this increase in rate of CO₂ is due to the action of the amino group as shown by the action of glycocoll. The results tend to show that the mode of action of H₂O₂ is one of dehydrogenation and that the action of the cystine is comparable to the Atmungskörper of Meyerhof.     

REGULATION OF HUMAN MYELOPOIESIS BY PROSTAGLANDIN E AND LACTOFERRIN

Studies on human myeloid stem cell proliferation indicate that progenitor cell populations committed to monocytoid differentiation are preferentially inhibited by prostaglandin E (PGE). the addition of PGE but not PGF to day 7 CFU_GM cultures upon initiation results in the dose-dependent inhibition of total colony and cluster formation. Morpholigical analysis of proliferating clones demonstrates that the effect of PGE on total colony and cluster formation results from the selective inhibition of monocyte-macrophage colony forming cells. Mixed monocytoid/neutrophil colony formation was markedly less sensitive and neutrophil and eosinophil colony formation essentially insensitive to the inhibitory effects of PGE. the inhibition of monocytoid colony formation by PGE₁ extends equally well to day 13 CFU_GM, but not to CFU_GM in suspension culture. the observed effects of PGE₁ on monocytoid committed pre-CFU_GM and day 7 and day 14 CFU_GM indicate that sensitivity to inhibition by PGE increases with progenitor cell maturity. Specificity analysis indicates that prostaglandins of the E series (PGE₁, PGE₂) are by far the most active naturally occurring prostanoate compounds inhibiting CFU_GM proliferation. The addition of iron saturated lactoferrin to liquid cultures of human peripheral blood monocytes, inclusion into mononuclear cell feeder layers or addition to agar cultures proliferating in response to endogenously produced CSFs, results in the equivalent inhibition of CSFs necessary for day 7 and day 14 monocytoid and/or neutrophil and eosinophil colony and cluster formation. These results indicate roles for PGE and lactoferrin in myeloid stem cell regulation in vitro and suggest that they may serve as physiological regulators of granulocyte and monocyte proliferation.     

THEORY AND MEASUREMENT OF VISUAL MECHANISMS : III. ΔI AS A FUNCTION OF AREA,INTENSITY, AND WAVE-LENGTH,FOR MONOCULAR AND BINOCULAR STIMULATION

Measurements of ΔI as a function of retinal area illuminated have been obtained at various levels of standard intensity I ₁, using "white" light and light of three modal wave-lengths (λ465, 525, 680), for monocular stimulation and for simultaneous excitation of the two eyes ("binocular"), using several methods of varying (rectangular) area and retinal location, with control of exposure time. For data homogeneous with respect to method of presentation, log ΔI_m = -Z log A + C, where ΔI = Ĩ ₂ – I ₁, A is area illuminated, and C is a terminal constant (= log ΔI_m for A = 1 unit) depending on the units in which ΔI and A are expressed, and upon I ₁. The equation is readily deduced on dimensional grounds, without reference to specific theories of the nature of ΔI or of retinal area in terms of its excitable units. Z is independent of the units of I and A. Experimentally it is found to be the same for monocular and binocular excitations, as is to be expected. Also as is expected it is not independent of λ, and it is markedly influenced by the scheme according to which A is varied; it depends directly upon the rate at which potentially excitable elements are added when A is made to increase. For simultaneous excitation of the two eyes (when of very nearly equivalent excitability), ΔĪ_B is less than for stimulation of either eye alone, at all levels of I ₁, A, λ. The mean ratio (ΔĪ_L + ΔĪ_R)/2 to ΔI^B was 1.38. For white light, doubling A on one retina reduces ΔI_m in the ratio 1.21, or a little less than for binocular presentation under the same conditions. These facts are consistent with the view that the properties of ΔI are quantitatively determined by events central to the retina. The measure σ_1ΔI of organic variation in discrimination of intensities and ΔI_m are found to be in simple proportion, independent of I ₁, A, λ (and exposure time). Variability (σ_1ΔI) is not a function of the mode of presentation, save that it may be slightly higher when both retinas are excited, and its magnitude (for a given level of ΔI_m) is independent of the law according to which the adjustable intensity I ₂ is instrumentally controlled.     

THE ACCUMULATION OF ELECTROLYTES : X. ACCUMULATION OF IODINE BY HALICYSTIS AND VALONIA

Analyses of the sap of Halicystis Osterhoutii and of Valonia macrophysa for iodide indicate accumulations of the order of 1000 to 10,000-fold in the first case, and 40 to 250-fold in the second case. The chemical potential of KI, NaI, HI, and CaI₂ is greater inside than outside.     

Characterization of a Photosynthesizing Reconstituted Spinach Chloroplast Preparation : REGULATION BY PRIMER, ADENYLATES, FERREDOXIN, AND PYRIDINE NUCLEOTIDES

A particulate preparation (MgP) capable of photosynthetic CO₂ assimilation without the addition of stromal protein was obtained by rupturing whole spinach (Spinacia oleracea var. America) chloroplasts in 15 millimolar MgCl₂ buffered with Tricine at pH 8.5. This CO₂ assimilation was dependent upon light, inorganic phosphate, ferredoxin, ADP, NAD or NADP, and primer. Excepting glycolate, the products of CO₂ fixation by MgP were similar to those found with whole chloroplasts.     

THE SORPTION OF BACTERIOPHAGE BY LIVING AND DEAD SUSCEPTIBLE BACTERIA : I. EQUILIBRIUM CONDITIONS

The above data relating to the antistaphylococcus phage and single strain of S. aureus with which previous papers have been concerned (9, 10, 11, 12), bring out the following points. (a) For live, resting, susceptible B suspended in broth as well as for B in a P-B mixture during the logarithmic phases of B growth and P formation, P is distributed in a manner typical of numerous materials soluble in both phases of a two phase system, i.e., distribution proceeds in accordance with the equation C_b/C_a = K where C_b = extracellular P/ml. of broth and C_a = intracellular P/ml. of B. The combination is quantitatively reversible. (b) With heat-killed, susceptible B, P distribution is of the adsorptive type, expressible in the form of the adsorption isotherm equation a = kC ^1/n. The average value of 1/n is 0.80 in agreement with the results of von Angerer (2). Under ordinary conditions dead B take up much more P than do live B, the reaction proceeding to > 99 per cent completion. The combination of P with dead B is not demonstrably reversible and with high initial P/B ratios saturation of B with P is effected. Bacteria killed at 65°C., 80°C. and 100°C. show no differences in adsorptive ability. (c) The rates at which live, resting, susceptible B and heat-killed, susceptible B remove P from solution do not differ significantly. Velocity constants of the process calculated from See PDF for Equation agree satisfactorily. It is shown that the time interval consumed is concerned with an actual reaction between P and B and not with diffusion of P through the broth to B. (d) P determinations have been found to serve as satisfactory indicators for B growth in P-B mixtures where [B] is to be maintained at a constant level. Very small increments in [B] give rise to measurable increases in P by virtue of the fact that dP/dt is proportional to a power of the rate dB/dt (9). (e) Similarly [P] estimations will detect death of B cells in P-live B suspensions. Dead B take up large amounts of P irreversibly; such P cannot function in the titration and the result is a sharp drop in [P] of controls.     

I. THE RELATION BETWEEN ATTACHMENT TO THE SUBSTRATUM AND INGESTION BY AMEBA IN STRYCHNINE SULFATE SOLUTION AND CONDITIONED MEDIA : II. BIOLOGICAL ASSAY OF CONDITIONED MEDIA

1. Strychnine sulfate 0.000069 M decreased percentage attachment to the substratum by Amoeba proteus in 0.0029 M NaCl from 77.3 to 1.3, in 0.0029 M KCl from 40.8 to 2.5, in 0.002 M CaCl₂ from 73.3 to 68.0, in 0.002 M MgCl₂ from 85.5 to 83.3. 2. Frequency of ingestion of chilomonads by Amoeba proteus is increased by adding strychnine sulfate to solutions of NaCl, KCl, or CaCl₂. Frequency of ingestion is increased in NaCl solution from 1.3 to 2.3, in KCl from 0.75 to 2.25, and in CaCl₂ from 1.1 to 1.9 chilomonads per minute. Ingestion is not significantly increased by the addition of strychnine to MgCl₂ solution. 3. Frequency of ingestion of food by Amoeba proteus is not closely correlated with attachment to the substratum in NaCl and KCl solutions to which strychnine sulfate is added. 4. Chilomonads adhere to the plasmalemma of Amoeba proteus in solutions of NaCl, KCl, or CaCl₂ containing strychnine, but in MgCl₂ plus strychnine only a few adhere to it. Strychnine appears to make the surface of the amebae and chilomonads sticky in the former but not in the latter. Frequency of ingestion is apparently correlated with adherence of chilomonads to the plasmalemma. 5. Attachment to the substratum and ingestion by Pelomyxa carolinensis is increased by dead Chilomonas, Colpidium, and Paramecium in aqueous solutions, by materials obtained from paramecia by alcoholic-ether extraction, and by solutions in which these organisms have lived. 6. Attachment to the substratum by Pelomyxa carolinensis is not closely correlated with kind or concentration of inorganic salts used in this study. 7. Materials were found in extracts of paramecia which had certain characteristics in common with choline esters. There is no reason to doubt that under certain conditions materials are present in aqueous and alcoholic extracts which are pharmacologically similar to choline and acetylcholine. 8. Aqueous suspensions of paramecia when subcutaneously injected into young mice for 21 days inhibit the gonadotropic luteinizing hormone of the pituitary. Ovaries from injected mice showed no corpora lutea, and the seminal vesicles from injected males were smaller and contained less fluid than those of the controls.     

DYNAMICS OF NERVE CELLS : II. THE TEMPERATURE COEFFICIENTS OF CARBON DIOXIDE PRODUCTION BY THE HEART GANGLION OF LIMULUS POLYPHEMUS.

1. It is possible to determine by the colorimetric method the rate of production of carbon dioxide by the cardiac ganglion of Limulus. 2. Carbon dioxide formation in the cardiac ganglion was found to run parallel to the rate of heart beat for different temperatures. 3. The conclusion seems justified that the rate of cardiac rhythm of Limulus depends upon a chemical reaction in the nerve cells of the cardiac ganglion and that this reaction is associated with the production of carbon dioxide since the rate of beat and the rate of CO₂ production are similarly affected by changes in temperature.     

THE EFFECTS OF RADIATIONS ON BIOLOGICAL SYSTEMS : II. IMMEDIATE AND SUBSEQUENT EFFECTS OF X-RAY IRRADIATION UPON RESPIRATION OF DROSOPHILA LARVAE

By means of measurement of CO₂ respiratory rates it has been possible to observe immediate and latent effects of x-ray irradiations upon Drosophila larvae. The observations were extended over a period of several days, the duration of the prepupal period being observed also. In every instance a significant decrease in the rate of CO₂ respiration was observed immediately after irradiation. This decrease was univariant with the period of irradiation within the experimental limits.     

ON THE RATE OF OXYGEN CONSUMPTION BY FERTILIZED AND UNFERTILIZED EGGS : IV. CHAETOPTERHS AND ARBACIA PUNCTULATA

1. Unfertilized eggs of Chaetopterus consume about 2.4 mm.³ O₂ per hour per 10 mm.³ eggs at 21°C. 2. In the 1st hour after fertilization, the fertilized eggs consume oxygen at about 53 or 54 per cent of this rate, which is about 1.3 mm.³ O₂ per hour per 10 mm.³ eggs at 21°C. 3. For the first 6 hours after fertilization, at 21°C., the curve of the rate of oxygen consumption is slightly asymmetrically sigmoid. The prefertilization rate is regained between 4½ and 5 hours after fertilization. Soon after 6 hours, ciliary activity begins, and the rate of oxygen consumption rises rapidly. 4. The unfertilized eggs of Arbacia punctulata consume about 0.36–0.5 mm.³ O₂ per hour per 10 mm.³ eggs at 21°C. The absolute determination is difficult as these eggs are highly sensitive to shaking in the manometer vessels, and these difficulties are discussed. 5. The fertilized eggs of Arbacia punctulata consume oxygen at the rate of about 2.0 mm.³ O₂ per hour per 10 mm.³ 21°C. At 1 hour after fertilization the rate is already rising. 6. A comparison of the absolute rates of oxygen consumption, and the changes in rate at fertilization of these and a number of other eggs, together with a theoretical discussion, and a discussion of discrepancies in measurements on the eggs of Arbacia punctulata, is contained in the fifth paper of this series (21).     

INFLUENCE OF THE CONCENTRATION OF ELECTROLYTES ON SOME PHYSICAL PROPERTIES OF COLLOIDS AND OF CRYSTALLOIDS

1. When a 1 per cent solution of a metal gelatinate, e.g. Na gelatinate, of pH = 8.4 is separated from distilled water by a collodion membrane, water will diffuse into the solution with a certain rate which can be measured by the rise of the level of the liquid in a manometer. When to such a solution alkali or neutral salt is added the initial rate with which water will diffuse into the solution is diminished and the more so the more alkali or salt is added. This depressing effect of the addition of alkali and neutral salt is greater when the cation of the electrolyte added is bivalent than when it is monovalent. This seems to indicate that the depressing effect is due to the cation of the electrolyte added. 2. When a neutral M/256 solution of a salt with monovalent cation (e.g. Na₂SO₄ or K₄Fe(CN)₆, etc.) is separated from distilled water by a collodion membrane, water will diffuse into the solution with a certain initial rate. When to such a solution alkali or neutral salt is added, the initial rate with which water will diffuse into the solution is diminished and the more so the more alkali or salt is added. The depressing effect of the addition of alkali or neutral salt is greater when the cation of the electrolyte added is bivalent than when it is monovalent. This seems to indicate that the depressing effect is due to the cation of the electrolyte added. The membranes used in these experiments were not treated with gelatin. 3. It can be shown that water diffuses through the collodion membrane in the form of positively charged particles under the conditions mentioned in (1) and (2). In the case of diffusion of water into a neutral solution of a salt with monovalent or bivalent cation the effect of the addition of electrolyte on the rate of diffusion can be explained on the basis of the influence of the ions on the electrification and the rate of diffusion of electrified particles of water. Since the influence of the addition of electrolyte seems to be the same in the case of solutions of metal gelatinate, the question arises whether this influence of the addition of electrolyte cannot also be explained in the same way, and, if this be true, the further question can be raised whether this depressing effect necessarily depends upon the colloidal character of the gelatin solution, or whether we are not dealing in both cases with the same property of matter; namely, the influence of ions on the electrification and rate of diffusion of water through a membrane. 4. It can be shown that the curve representing the influence of the concentration of electrolyte on the initial rate of diffusion of water from solvent into the solution through the membrane is similar to the curve representing the permanent osmotic pressure of the gelatin solution. The question which has been raised in (3) should then apply also to the influence of the concentration of ions upon the osmotic pressure and perhaps other physical properties of gelatin which depend in a similar way upon the concentration of electrolyte added; e.g., swelling. 5. When a 1 per cent solution of a gelatin-acid salt, e.g. gelatin chloride, of pH 3.4 is separated from distilled water by a collodion membrane, water will diffuse into the solution with a certain rate. When to such a solution acid or neutral salt is added—taking care in the latter case that the pH is not altered—the initial rate with which water will diffuse into the solution is diminished and the more so the more acid or salt is added. Water diffuses into a gelatin chloride solution through a collodion membrane in the form of negatively charged particles. 6. When we replace the gelatin-acid salt by a crystalloidal salt, which causes the water to diffuse through the collodion membrane in the form of negatively charged particles, e.g. M/512 Al₂Cl₆, we find that the addition of acid or of neutral salt will diminish the initial rate with which water diffuses into the M/512 solution of Al₂Cl₆, in a similar way as it does in the case of a solution of a gelatin-acid salt.     

GALVANOTROPISM AND "REVERSAL OF INHIBITION" BY STRYCHNINE

The cathodically galvanotropic orientation of nemerteans, Lineus, and the anodic orientation of the gephyrean Echiurus, are reversed by the action of strychnine under conditions such that the typical "reversal of inhibition" induced by this substance is apparent. Nicotine does not give this result. Since it is necessary to assume that the strychnine effect is due to action upon the central ganglia, and since the galvanotropic effect depends upon action of the current on nerve cell bodies of the central ganglia, it must be assumed that the locus of reversal by strychnine is not perikaryal, but presumably synaptic.     

Host-Pathogen Interactions : XVIII. ISOLATION AND BIOLOGICAL ACTIVITY OF GLYCINOL, A PTEROCARPAN PHYTOALEXIN SYNTHESIZED BY SOYBEANS

A previously unrecognized phytoalexin has been isolated from soybean cotyledons that had been infected with bacteria or exposed to ultraviolet light. The phytoalexin has been purified to homogeneity by silica gel flash chromatography and high pressure liquid chromatography. It has been structurally characterized by its ultraviolet, circular dichroism and nuclear magnetic resonance spectra, polarimetry, and its mass spectrometric fragmentation pattern. The phytoalexin, (6aS,11aS)-3,6a,9-trihydroxypterocarpan, is a compound that had previously been detected in CuCl₂-treated soybeans and is structurally related to the previously identified soybean phytoalexins glycerollins I to IV. It is proposed that the trivial name glycinol be used for this phytoalexin. Glycinol is a broad spectrum antibiotic capable of prolonging the lag phase of growth of all six bacteria examined, namely Erwinia carotovora, Pseudomonas glycinea (races 1 and 3), Escherichia coli, Xanthomonas phaseoli, and Bacillus subtilis. Glycinol also inhibits the growth of the fungi Phytophthora megasperma f. sp. glycinea (race 1), Saccharomyces cerevisiae, and Cladosporium cucumerinum. Glycinol is a static agent against the six bacterial species listed above and against S. cerevisiae, and appears to be static against the other fungi examined. As with other phytoalexins, there is no correlation between the pathogenicity of a microorganism and its sensitivity to glycinol.     

COMPARATIVE STUDIES ON RESPIRATION : X. TOXIC AND ANTAGONISTIC EFFECTS OF MAGNESIUM IN RELATION TO THE RESPIRATION OF BACILLUS SUBTILIS.

1. Concentrations of MgCl₂ up to 0.01 M have little effect upon the rate or respiration of Bacillus subtilis; at 0.03 M there is an increase in the rate, while in the higher concentrations there is a gradual decrease. 2. There is a well marked antagonism between MgCl₂ and NaCl, and a very slight antagonism between MgCl₂ and CaCl₂.     

STIMULATION OF COLLAGEN SYNTHESIS IN RAT CARDIAC FIBROBLASTS BY EXPOSURE TO HYPOXIC CULTURE CONDITIONS AND SUPPRESSION OF THE EFFECT BY NATRIURETIC PEPTIDES

Synthesis of type I and type III collagens by rat cardiac fibroblasts was stimulated when the cells were cultured under 95% N₂/5% CO₂for one hour followed by incubation under normoxic conditions for 24 hours. The stimulative effect was attenutated by the presence of atrial natriuretic peptide (ANP, 10⁻⁶m) or brain natriuretic peptide (BNP, 10⁻⁶m) in the culture medium. Northern blot analysis indicated that α1(I) and α1(III) collagen mRNA levels were also increased by hypoxia, and decreased with the addition of ANP or BNP in a dose-dependent manner. These results indicate interaction between intracellular signals of a physical stimulus (hypoxic stress) and those of a chemical one (ANP or BNP) and demonstrate that both signals regulate collagen synthesis by cardiac fibroblasts at the levels of the mRNAs. The results also suggest that natriuretic peptides produced by cardiomyocytesin vivomay function as paracrine factors that play a role in the prevention of cardiac fibrosis in ischaemic heart diseases.     

EFFECT OF CYSTEINE AND METHIONINE ON SULFATE UPTAKE AND PRIMARY PRODUCTIVITY BY AXENIC ALGAL CULTURES AND LAKE MICROPLANKTON COMMUNITIES1

The presence of up to 500 μg sulfur·l^?1 of an equimolar mixture of cysteine and methionine had virtually no effect on the SO₄^2- uptake rate of Navicula pelliculosa, (Bréb.) Hilse whereas the rate of Ankistrodesmus falcatus (Corda) Ralfs was decreased by the presence of 500 μg S· l^?1 and Anabaena flos-aquae (Lyngbye) Bréb. by 50 μg S·l^?1. Primary productivity in these axenic cultures was affected (decreased) only in A. falcatus. The C:S uptake ratio was lowest in N. pelliculosa and highest in A. falcatus. Considering these species as representative of groups of naturally occurring algae, patterns of SO₄^2- uptake and primary productivity in a eutrophic and a moderately oligotrophic lake reflected the results of the algal culturing experiments: SO₄^2- uptake rates, relative to primary productivity, were higher in the presence of diatoms and bluegreen algae and lower when green algae were present; the addition of the cysteine I methionine mixture to the lake waters decreased the rate of microplankton SO₄^2- uptake in correlation with the makeup of the algal community; primary productivity decreased upon the addition of cysteine I methionine when green algae were relatively abundant. It is concluded that, in most fresh water systems, the effects of organic sulfur pollution on algal SO₄^2- uptake and primary productivity are insignificant as compared to other ecological changes that occur due to that pollution.     

THE OXIDATION OF SODIUM LACTATE BY HYDROGEN PEROXIDE

By means of a modification of the technique of the Osterhout apparatus it is possible to follow the production of CO₂ from sodium lactate when acted upon by H₂O₂. The results of this process indicate that the reaction is not a simple one but is of an autocatalytic type. This conclusion is borne out by the fact that the determinations of H₂O₂ during the reaction show an increased amount of peroxide during the earlier stages of the reaction. This is considered to be due to the formation of a peroxide by the oxidation of the acetaldehyde (formed by the interaction of H₂O₂ and sodium lactate) with the oxygen of the air. When the reaction is carried out in an atmosphere of nitrogen no increase is observed. Further experiments in nitrogen tend to show that acetaldehyde is the end-product of the action of H₂O₂ alone. The effect of FeCl₃ upon the reaction depends upon the previous treatment of the iron salt. If the iron solution is added to the H₂O₂ before mixing with the lactate there is an increased amount of CO₂. If, however, the iron is added to the lactate before the addition of the peroxide, the action tends to inhibit the production of CO₂. The reaction of H₂O₂ with sodium lactate is comparable to the action of killed yeast and methylene blue as determined by Palladin and his coworkers.