bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECTS OF SOME INHIBITORS ON THE RATES OF PHOTOSYNTHESIS AND RESPIRATION BY CHLORELLA
Authors: Yuan Edward Lung , Daniels Farrington
Published: May 2004

The effects of several inhibitors on the rates of photosynthesis and of respiration by Chlorella pyrenoidosa have been studied. The inhibitors used in this study include potassium cyanide, hydroxylamine hydrogen chloride, dinitrophenol,and sodium azide. Each inhibitor seems to have its own characteristic action in photosynthesis and in respiration. With the exception of hydroxylamine, all the inhibitors show a stimulation of respiration at low concentrations of the inhibitors. Only dinitrophenol inhibits respiration to a marked extent. Potassium cyanide, hydroxylamine, and dinitrophenol are about equally effective in inhibiting photosynthesis, but sodium azide is nearly ten times as effective.
PHOTOREVERSAL OF NUCLEAR AND CYTOPLASMIC EFFECTS OF SHORT ULTRAVIOLET RADIATION ON PARAMECIUM CAUDATUM
Authors: Brandt C. L. , Giese A. C.
Published: May 2004

1. Irradiation with three short ultraviolet (UV) wave lengths, 226, 233, and 239 mµ rapidly immobilizes Paramecium caudatum, the dosage required being smaller the shorter the wave length. 85 per cent of paramecia immobilized with wave length 226 mµ recover completely. Recovery from immobilizing doses is less the longer the wave length.

2. Irradiation continued after immobilization kills the paramecia in a manner which is markedly different for very short (226, 233, and 239 mµ) and longer (267 mµ) wave lengths.

3. An action spectrum for immobilization in P. caudatum was determined for the wave lengths 226, 233, 239, 248, and 267 mµ, and found to resemble the absorption of protein and lipide in the wave length region below 248 mµ. Addition of these data to those of Giese (1945 b) gives an action spectrum resembling the absorption by albumin-like protein.

4. Division of P. caudatum is delayed by doses of wave lengths 226, 233, and 239 mµ which cause immobilization, the longest wave length being most effective.

5. Immobilization at any of the wave lengths tested (226, 233, 239, 248, 267 mµ) is not photoreversible when UV-treated paramecia are concurrently illuminated.

6. Division delay resulting from immobilizing doses of 226, 233, and 239 mµ is photoreversible by exposure to visible light concurrently with the UV.

7. Division delay induced by exposure to wave length 267 mµ is reduced by exposure to visible light applied concurrently with UV or immediately afterwards.

8. The data suggest that the shortest UV wave length tested (226 mµ) affects the cytoplasm selectively, because it is absorbed superficially as indicated by unilateral fluorescence in UV. Consequently it immobilizes paramecia rapidly but has little effect on the division rate because little radiation reaches the nucleus.

9. The data support the view that nuclear effects of UV are readily photoreversed but cytoplasmic effects are not.
COMPARATIVE HYDROLYSIS OF GELATIN BY PEPSIN, TRYPSIN, ACID, AND ALKALI
Authors: Northrop John H.
Published: May 2004

A comparison has been made of the relative velocity of hydrolysis of the various peptid linkings of the gelatin molecule when hydrolyzed by acid, alkali, pepsin or trypsin. It has been found that:

1. Those linkages which are most rapidly split by pepsin or trypsin are among the more resistant to acid hydrolysis.

2. Those linkages which are hydrolyzed by pepsin are also hydrolyzed by trypsin.

3. Trypsin hydrolyzes linkages which are not attacked by pepsin.

4. Of the linkages which are hydrolyzed by both enzymes, those which are most rapidly hydrolyzed by pepsin are only slowly attacked by trypsin.

5. Those linkages which are attacked by trypsin or pepsin are among the ones first (most rapidly) hydrolyzed by alkali.

In general it may be said that the course of the early stages of hydrolysis of gelatin is similar with alkali, trypsin, or pepsin and quite different with acid.
THE NATURE OF FOVEAL DARK ADAPTATION
Authors: Hecht Selig
Published: May 2004

1. After a discussion of the sources of error involved in the study of dark adaptation, an apparatus and a procedure are described which avoid these errors. The method includes a control of the initial light adaptation, a record of the exact beginning of dark adaptation, and an accurate means of measuring the threshold of the fovea after different intervals in the dark.

2. The results show that dark adaptation of the eye as measured by foveal vision proceeds at a very precipitous rate during the first few seconds, that most of the adaptation takes place during the first 30 seconds, and that the process practically ceases after 10 minutes. These findings explain much of the irregularity of the older data.

3. The changes which correspond to those in the fovea alone are secured by correcting the above results in terms of the movements of the pupil during dark adaptation.

4. On the assumption that the photochemical effect of the light is a linear function of the intensity, it is shown that the dark adaptation of the fovea itself follows the course of a bimolecular reaction. This is interpreted to mean that there are two photolytic products in the fovea; that they are disappearing because they are recombining to form anew the photosensitive substance of the fovea; and that the concentration of these products of photolysis in the sense cell must be increased by a definite fraction in order to produce a visual effect.

5. It is then suggested that the basis of the initial event in foveal light perception is some mechanism that involves a reversible photochemical reaction of which the "dark" reaction is bimolecular. Dark adaptation follows the "dark" reaction; sensory equilibrium is represented by the stationary state; and light adaptation by the shifting of the stationary state to a fresh point of equilibrium toward the "dark" side of the reaction.
THE SELECTIVE ABSORPTION OF POTASSIUM BY ANIMAL CELLS
Authors: Mitchell Philip H. , Wilson J. Walter , Stanton Ralph E.
Published: May 2004

1. Frog muscles perfused with Ringer solution in which potassium chloride has been replaced by an equivalent amount of rubidium or cesium chloride take up rubidium or cesium and incorporate them into the tissue substance in such form as to be retained during a subsequent perfusion with potassium-free Ringer solution, provided the muscles contract during the first perfusion. Retention of rubidium or cesium by a resting muscle does not occur.

2. Rats on synthetic diets, adequate in all respects except that potassium was replaced by an equivalent amount of rubidium or cesium, died after a period varying from 10 to 17 days with characteristic symptoms including tetanic spasms. Muscle, heart, liver, kidney, spleen, and lung tissues were then found to contain significant amounts of rubidium or cesium. The concentration of these metals in the muscle amounted, in some cases, as shown by a spectroscopic estimation, to about half the concentration of potassium normally found in mammallian muscle.

3. The results are regarded as tending to confirm the theory that the peculiarities in the physiological effects of potassium, including the facility with which it is "selected" by living cells in preference to sodium, are related to the electronic structure of the potassium ion as compared with that of similar ions. The possible relationship of the comparative migration velocity, a function of the electronic structure, to physiological effects is suggested.
COMPARATIVE STUDIES ON RESPIRATION
Authors: Inman O. L.
Published: May 2004

The respiration of Chlorella is diminished by exposure to hypertonic salt solutions. After a short exposure there is complete recovery when the algæ are removed to the normal medium. After a longer exposure recovery may be incomplete, as shown by the fact that the rate of respiration fails to rise to the normal level. Staining with methylene blue indicates that few, if any, of the cells are killed as the result of the exposure. It would therefore seem that the treatment produces a persistent lowering of the rate of metabolism. Such a condition of metabolism is also found after exposure to chloroform.
DIRECT AND INDIRECT DETERMINATIONS OF PERMEABILITY
Authors: Osterhout W. J. V.
Published: May 2004

1. Methods are described for obtaining cell sap from Nitella without contamination.

2. Tests of the cell sap show that in a balanced solution of NaNO3 plus Ca(NO3)2 there is a slow penetration of NO3 and that the cell remains in a normal condition, but in pure NaNO3 there is rapid penetration accompanied by injury.

3. Inasmuch as determinations of electrical conductivity give the same result it may be concluded that this method gives reliable information regarding permeability.

4. While observations on recovery from plasmolysis give similar results, the method is less satisfactory.
THE ORIGIN OF THE ELECTRICAL CHARGES OF COLLOIDAL PARTICLES AND OF LIVING TISSUES
Authors: Loeb Jacques
Published: May 2004

1. When a solution of a salt of gelatin or crystalline egg albumin is separated by a collodion membrane from a watery solution (free from protein) a potential difference is set up across the membrane in which the protein is positively charged in the case of protein-acid salts and in which the protein is negatively charged in the case of metal proteinates. The turning point is the isoelectric point of the protein.

2. Measurements of the pH of the (inside) protein solution and of the outside watery solution show that when equilibrium is established the value pH inside minus pH outside is positive in the case of protein-acid salts and negative in the case of metal proteinates. This is to be expected when the P.D. is caused by the establishment of a Donnan equilibrium, since in that case the pH should be lower outside than inside in the case of a protein-acid salt and should be higher outside than inside in the case of a metal proteinate.

3. At the isoelectric point where the electrical charge is zero the value of pH inside minus pH outside becomes also zero.

4. It is shown that a P.D. is established between suspended particles of powdered gelatin and the surrounding watery solution and that the sign of charge of the particles is positive when they contain gelatin-acid salts, while it is negative when the powdered particles contain metal gelatinate. At the isoelectric point the charge is zero.

5. Measurements of the pH inside the powdered particles and of the pH in the outside watery solution show that when equilibrium is established the value pH inside minus pH outside is positive when the powdered particles contain a gelatin-acid salt, while the value pH inside minus pH outside is negative when the powdered particles contain Na gelatinate. At the isoelectric point the value pH inside minus pH outside is zero.

6. The addition of neutral salts depresses the electrical charge of the powdered particles of protein-acid salts. It is shown that the addition of salts to a suspension of powdered particles of gelatin chloride also diminishes the value of pH inside minus pH outside.

7. The agreement between the values 58 (pH inside minus pH outside) and the P. D. observed by the Compton electrometer is not only qualitative but quantitative. This proves that the difference in the concentration of acid (or alkali, as the case may be) in the two phases is the only cause for the observed P.D.

8. The Donnan theory demands that the P.D. of a gelatin chloride solution should be 1½ times as great as the P.D. of a gelatin sulfate solution of the same pH and the same concentration (1 per cent) of originally isoelectric gelatin. This is found to be correct and it is also shown that the values of pH inside minus pH outside for the two solutions possess the ratio of 3:2.

9. All these measurements prove that the electrical charges of suspended particles of protein are determined exclusively by the Donnan equilibrium.
CHANGE OF ACID AGGLUTINATION OPTIMUM AS INDEX OF BACTERIAL MUTATION
Authors: De Kruif Paul H.
Published: May 2004

A distinct difference in acid agglutination optimum for Type D (bacillus of rabbit septicemia) and its mutant form, Type G, has been observed. The optimum for Type D lies between pH 3.5 and pH 3.0. This changes during mutation, the resulting Type G mutants having in general an optimum lying between pH 4.7 and pH 3.8.

The constancy of the optimum for Type D is very strict, while that for Type G is slightly less so. The variation is never so great as to cause an overlapping of optima and consequent failure of differentiation.

These acid agglutination optima are in the nature of physical constants for the two types and would imply a fundamental difference in the chemical constitution of the organisms.

Animal passage, far from causing a reversion of the mutant Type G to the primordial Type D form, brings about a still greater instability in the presence of H ions.
BANANA GEL
Authors: McGuire Grace , Falk K. George
Published: May 2004

The conditions for the formation of gels from banana extracts were studied.

Gels were obtained with extracts more alkaline than pH 7.0 with very small quantities of calcium, strontium, and barium salts, the gel formation with these salts decreasing in the indicated order.

In solutions more acid than pH 6.0, no gels were obtained with these salts.

Magnesium, lithium, and sodium salts did not cause gel formation either in acid or alkaline solutions.

Pancreatine gave a gel on incubation with banana extract at pH 5.0.

The gel-forming property of banana extracts was destroyed on boiling.
QUANTITATIVE LAWS IN REGENERATION
Authors: Loeb Jacques
Published: May 2004

It is well known that a long defoliated piece of stem of Bryophyllum calycinum forms shoots only at the apical or the two apical nodes, while when such a stem is cut into as many pieces as there are nodes each node produces shoots. It is shown in this paper that the dry weight of shoots produced in the apical nodes of a long piece of stem is approximately equal to the dry weight of shoots the same stem would have produced if it had been cut into as many pieces as it possesses nodes. Hence all the material which can be used for the growth of shoots goes into the most apical part of the stem and this accounts for the polar character of regeneration in this case.

It seems that the mass of basal roots produced by a piece of defoliated stem also increases with the mass of the stem.
DOES THE KINETICS OF TRYPSIN DIGESTION DEPEND ON THE FORMATION OF A COMPOUND BETWEEN ENZYME AND SUBSTRATE
Authors: Northrop John H.
Published: May 2004

1. The velocity of hydrolysis of gelatin by trypsin increases more slowly than the gelatin concentration and finally becomes nearly independent of the gelatin concentration. The relative velocity of hydrolysis of any two substrate concentrations is independent of the quantity of enzyme used to make the comparison.

2. The rate of hydrolysis is independent of the viscosity of the solution.

3. The percentage retardation of the rate of hydrolysis by inhibiting substances, is independent of the substrate concentration.

4. There is experimental evidence that the enzyme and inhibiting substance are combined to form a widely dissociated compound.

5. If the substrate were also combined with the enzyme, an increase in the substrate concentration should affect the equilibrium between the enzyme and the inhibiting substance. This is not the case.

6. The rate of digestion of a mixture of casein and gelatin is equal to the sum of the rates of hydrolysis of the two substances alone, as it should be if the rate is proportional to the concentration of free enzyme. This contradicts the saturation hypothesis.

7. If the reaction is followed by determining directly the change in the substrate concentration, it is found that this change agrees with the law of mass action; i.e., the rate of digestion is proportional to the substrate concentration.
EFFECT OF COCAINE ON THE GROWTH OF LUPINUS ALBUS. A CONTRIBUTION TO THE COMPARATIVE PHARMACOLOGY OF ANIMAL AND PLANT PROTOPLASM
Authors: Macht David I. , Livingston Marguerite B.
Published: May 2004

1. The effects of cocaine and its decomposition products were studied on the growth of the young roots of Lupinus albus.

2. The results obtained were compared with similar experiments on animal tissues.

3. It was found that, while cocaine is the most toxic of these compounds studied for animal tissues, it was of comparatively low toxicity in respect to its effect on the growth of roots. On the other hand, sodium benzoate, being practically non-toxic for animals, was the most toxic of the compounds studied for the plant roots.
STUDIES ON THE REGULATION OF OSMOTIC PRESSURE
Authors: Palmer Walter W. , Atchley Dana W. , Loeb Robert F.
Published: May 2004

Egg albumin, like gelatin, influences the conductivity of a 0.6 per cent NaCl solution in two ways: (a) At an hydrogen ion concentration of about pH 3.0, increasing concentrations increase the conductivity. (b) Near the isoelectric point of albumin and at the pH of the blood, increasing concentrations of albumin decrease the conductivity of the NaCl solution.
THE COLLOIDAL BEHAVIOR OF EDESTIN
Authors: Hitchcock David I.
Published: May 2004

1. It has been shown by titration experiments that the globulin edestin behaves like an amphoteric electrolyte, reacting stoichiometrically with acids and bases.

2. The potential difference developed between a solution of edestin chloride or acetate separated by a collodion membrane from an acid solution free from protein was found to be influenced by salt concentration and hydrogen ion concentration in the way predicted by Donnan's theory of membrane equilibrium.

3. The osmotic pressure of such edestin-acid salt solutions was found to be influenced by salt concentration and by hydrogen ion concentration in the same way as is the potential difference.

4. The colloidal behavior of edestin is thus completely analogous to that observed by Loeb with gelatin, casein, and egg albumin, and may be explained by Loeb's theory of colloidal behavior, which is based on the idea that proteins react stoichiometrically as amphoteric electrolytes and on Donnan's theory of membrane equilibrium.
THE ELIMINATION OF DISCREPANCIES BETWEEN OBSERVED AND CALCULATED P.D. OF PROTEIN SOLUTIONS NEAR THE ISOELECTRIC POINT WITH THE AID OF BUFFER SOLUTIONS
Authors: Loeb Jacques
Published: May 2004

1. It had been noticed in the previous experiments on the influence of the hydrogen ion concentration on the P.D. between protein solutions inside a collodion bag and aqueous solutions free from protein that the agreement between the observed values and the values calculated on the basis of Donnan's theory was not satisfactory near the isoelectric point of the protein solution. It was suspected that this was due to the uncertainty in the measurements of the pH of the outside aqueous solution near the isoelectric point. This turned out to be correct, since it is shown in this paper that the discrepancy disappears when both the inside and outside solutions contain a buffer salt.

2. This removes the last discrepancy between the observed P.D. and the P. D. calculated on the basis of Donnan's theory of P.D. between membrane equilibria, so that we can state that the P.D. between protein solutions inside collodion bags and outside aqueous solutions free from protein can be calculated from differences in the hydrogen ion concentration on the opposite sides of the membrane, in agreement with Donnan's formula.
ELECTRICAL CHARGES OF COLLOIDAL PARTICLES AND ANOMALOUS OSMOSIS
Authors: Loeb Jacques
Published: May 2004

1. When solutions of KCl, NaCl, or LiCl are separated from water without salt by a collodion-gelatin membrane and when the pH of both salt solution and water are on the acid side of the isoelectric point of gelatin, water diffuses from the side of pure water into the salt solution at a rate increasing inversely with the radius of the cations.

2. The adsorption theory would lead us to assume that this influence of the cations is due to an increase of the P.D. between the liquid and the membrane inside the pores of the gelatin film of the membrane, but direct measurements of this P.D. contradict such an assumption, since they show that the influence of the three salts on this P.D. is identical at pH 3.0.

3. It is found, however, that the P.D. across the membrane is affected in a similar way by the three cations as is the transport of water through the membrane.

4. This P.D. across the membrane varies inversely as the relative mobility of the three cations which suggests that the influence of the three cations on the diffusion of liquid through the membrane is partly if not essentially due to a diffusion potential.
THE STABILITY OF BACTERIAL SUSPENSIONS
Authors: Northrop John H. , De Kruif Paul H.
Published: May 2004

1. The addition of proteins or serum to suspensions of bacteria, (Bacillus typhosus or rabbit septicemia) at different pH widens the acid agglutination zone and shifts the isoelectric point to that of the added substance.

2. The amount of serum required to agglutinate is much less near the acid agglutination point of the organisms.

3. The addition of immune serum prevents the salt from decreasing the cohesive force between the organisms, and agglutination therefore is determined solely by the potential, provided excess immune body is present. Whenever the potential is decreased below 15 millivolts the suspension agglutinates.
STUDIES IN THE PHYSICAL CHEMISTRY OF THE PROTEINS
Authors: Cohn Edwin Joseph
Published: May 2004

1. Two proteins of the globulin type, serum globulin and tuberin, and the protein of milk, casein, have been purified (a) of the other proteins and (b) of the inorganic electrolytes with which they exist in nature. The methods that were employed are described.

2. All three proteins were found to be only very slightly soluble in water in the pure uncombined state. The solubility of each was accurately measured at 25.0° ± 0.1°C. The most probable solubility of the pseudoglobulin of serum was found to be 0.07 gm. in 1 liter; of tuberin 0.1 gm. and of casein 0.11 gm. The methods that were employed in their determination are described.

3. Each protein investigated dissolved in water to a constant and characteristic extent when the amount of protein precipitate with which the solution was in heterogeneous equilibrium was varied within wide limits. The solubility of a pure protein is therefore proposed as a fundamental physicochemical constant, which may be used in identifying and in classifying proteins.

4. The concentration of protein dissolved must be the sum of the concentration of the undissociated protein molecule which is in heterogeneous equilibrium with the protein precipitate, and of the concentration of the dissociated protein ions.

5. The dissociated ions of the dissolved protein give a hydrogen ion concentration to water that is also a characteristic of each protein.
THE COMBINATION OF GELATIN WITH HYDROCHLORIC ACID
Authors: Hitchcock David I.
Published: May 2004

The amount of HCl combined with a given weight of gelatin has been determined by hydrogen electrode measurements in 1 per cent, 2.5 per cent, and 5 per cent solutions of gelatin in HCl of various concentrations, by correcting for the amount of HCl necessary to give the same pH to an equal volume of water without protein. The curve so obtained indicates that the amount of HCl combined with 1 gm. of gelatin is constant between pH 1 and 2, being about 0.00092 moles.
THE MECHANISM BY WHICH TRIVALENT AND TETRAVALENT IONS PRODUCE AN ELECTRICAL CHARGE ON ISOELECTRIC PROTEIN
Authors: Loeb Jacques
Published: May 2004

1. Experiments on anomalous osmosis suggested that salts with trivalent cations, e.g. LaCl3, caused isoelectric gelatin to be positively charged, and salts with tetravalent anions, e.g. Na4Fe(CN)6, caused isoelectric gelatin to be negatively charged. In this paper direct measurements of the P.D. between gels of isoelectric gelatin and an aqueous solution as well as between solutions of isoelectric gelatin in a collodion bag and an aqueous solution are published which show that this suggestion was correct.

2. Experiments on anomalous osmosis suggested that salts like MgCl2, CaCl2, NaCl, LiCl, or Na2SO4 produce no charge on isoelectric gelatin and it is shown in this paper that direct measurements of the P.D. support this suggestion.

3. The question arose as to the nature of the mechanism by which trivalent and tetravalent ions cause the charge of isoelectric proteins. It is shown that salts with such ions act on isoelectric gelatin in a way similar to that in which acids or alkalies act, inasmuch as in low concentrations the positive charge of isoelectric gelatin increases with the concentration of the LaCl3 solution until a maximum is reached at a concentration of LaCl3 of about M/8,000; from then on a further increase in the concentration of LaCl3 diminishes the charge again. It is shown that the same is true for the action of Na4Fe(CN)6. From this it is inferred that the charge of the isoelectric gelatin under the influence of LaCl3 and Na4Fe(CN)6 at the isoelectric point is due to an ionization of the isoelectric protein by the trivalent or tetravalent ions.

4. This ionization might be due to a change of the pH of the solution, but experiments are reported which show that in addition to this influence on pH, LaCl3 causes an ionization of the protein in some other way, possibly by the formation of a complex cation, gelatin-La. Na4Fe(CN)6 might probably cause the formation of a complex anion of the type gelatin-Fe(CN)6. Isoelectric gelatin seems not to form such compounds with Ca, Na, Cl, or SO4.

5. Solutions of LaCl3 and Na4Fe(CN)6 influence the osmotic pressure of solutions of isoelectric gelatin in a similar way as they influence the P.D., inasmuch as in lower concentrations they raise the osmotic pressure of the gelatin solution until a maximum is reached at a concentration of about M/2,048 LaCl3 and M/4,096 Na4Fe(CN)6. A further increase of the concentration of the salt depresses the osmotic pressure again. NaCl, LiCl, MgCl2, CaCl2, and Na2SO4 do not act in this way.

6. Solutions of LaCl3 have only a depressing effect on the P.D. and osmotic pressure of gelatin chloride solutions of pH 3.0 and this depressing effect is quantitatively identical with that of solutions of CaCl2 and NaCl of the same concentration of Cl.
IONIZING INFLUENCE OF SALTS WITH TRIVALENT AND TETRAVALENT IONS ON CRYSTALLINE EGG ALBUMIN AT THE ISOELECTRIC POINT
Authors: Loeb Jacques
Published: May 2004

1. While crystalline egg albumin is highly soluble in water at low temperature at the pH of its isoelectric point, it is coagulated by heating. It has long been known that this coagulation can be prevented by adding either acid or alkali, whereby the protein is ionized.

2. It is shown in this paper that salts with trivalent or tetravalent ions, e.g. LaCl3 or Na4Fe(CN)6, are also able to prevent the heat coagulation of albumin at the isoelectric point (i.e. pH 4.8), while salts with a divalent ion, e.g. CaCl2, BaCl4, Na2SO4, or salts like NaCl, have no such effect.

3. This is in harmony with the fact shown in a preceding paper that salts with trivalent or tetravalent ions can cause the ionization of proteins at its isoelectric point and thus give rise to a membrane potential between micellæ of isoelectric protein and surrounding aqueous solution, while the above mentioned salts with divalent and monovalent ions have apparently no such effect.
ON THE INFLUENCE OF AGGREGATES ON THE MEMBRANE POTENTIALS AND THE OSMOTIC PRESSURE OF PROTEIN SOLUTIONS
Authors: Loeb Jacques
Published: May 2004

1. It is shown that when part of the gelatin in a solution of gelatin chloride is replaced by particles of powdered gelatin (without change of pH) the membrane potential of the solution is influenced comparatively little.

2. A measurement of the hydrogen ion concentration of the gelatin chloride solution and the outside aqueous solution with which the gelatin solution is in osmotic equilibrium, shows that the membrane potential can be calculated from this difference of hydrogen ion concentration with an accuracy of half a millivolt. This proves that the membrane potential is due to the establishment of a membrane equilibrium and that the powdered particles participate in this membrane equilibrium.

3. It is shown that a Donnan equilibrium is established between powdered particles of gelatin chloride and not too strong a solution of gelatin chloride. This is due to the fact that the powdered gelatin particles may be considered as a solid solution of gelatin with a higher concentration than that of the weak gelatin solution in which they are suspended. It follows from the theory of membrane equilibria that this difference in concentration of protein ions must give rise to potential differences between the solid particles and the weaker gelatin solution.

4. The writer had shown previously that when the gelatin in a solution of gelatin chloride is replaced by powdered gelatin (without a change in pH), the osmotic pressure of the solution is lowered the more the more dissolved gelatin is replaced by powdered gelatin. It is therefore obvious that the powdered particles of gelatin do not participate in the osmotic pressure of the solution in spite of the fact that they participate in the establishment of the Donnan equilibrium and in the membrane potentials.

5. This paradoxical phenomenon finds its explanation in the fact that as a consequence of the participation of each particle in the Donnan equilibrium, a special osmotic pressure is set up in each individual particle of powdered gelatin which leads to a swelling of that particle, and this osmotic pressure is measured by the increase in the cohesion pressure of the powdered particles required to balance the osmotic pressure inside each particle.

6. In a mixture of protein in solution and powdered protein (or protein micellæ) we have therefore two kinds of osmotic pressure, the hydrostatic pressure of the protein which is in true solution, and the cohesion pressure of the aggregates. Since only the former is noticeable in the hydrostatic pressure which serves as a measure of the osmotic pressure of a solution, it is clear why the osmotic pressure of a protein solution must be diminished when part of the protein in true solution is replaced by aggregates.
CHANGES IN THE DURATION OF THE ELECTRIC RESPONSE OF SINGLE NERVE FIBERS FOLLOWING REPETITIVE STIMULATION
Authors: Spyropoulos Constantine S.
Published: May 2004

Single nerve fibers were isolated from the nerve innervating the sartorius or semitendinosus muscle of the toad (Bufo marinus). Single nerve fiber responses were recorded with three arrangements of the "bridge insulator" method. During stimulation at 50 to 150 pulses per second for 20 to 140 minutes the spike duration was progressively increased. After tetanization the spike duration usually continued to increase at a more rapid rate. Within 5 to 60 minutes further prolongation stopped and within 1 to 10 hours the spike duration was normal. The duration of the response of tetanized fibers was from 2.5 to more than 10 times the spike duration of untetanized fibers. Prolongation was observed in nerve fibers isolated from nerves tetanized in vivo.
ALTERATION BY DINITROCRESOL OF PATHWAYS FOR GLUCOSE OXIDATION IN EGGS OF ARBACIA PUNCTULATA
Authors: Keltch A. K. , Krahl M. E. , Clowes G. H. A.
Published: May 2004

1. The C14O2 production by Arbacia eggs and embryos from glucose-1-C14, glucose-2-C14, and glucose-6-C14 has been measured without and with dinitrocresol in the incubation medium. In the absence of the dinitrocresol, the C14O2 production from glucose-1-C14 is more rapid than from glucose-2-C14 and much more rapid than from glucose-6-C14; this, together with previous findings, indicates that glucose is utilized in Arbacia eggs predominantly via the TPN shunt rather than via the aldolase step of the glycolytic pathway. In the presence of the dinitrocresol, C14O2 from glucose-6-C14 approaches that from glucose-1-C14, indicating that, in the presence of this reagent, glucose utilization is diverted from the shunt to the glycolytic pathway.

2. Incorporation of C14 from glucose labelled in the 1-, 2-, or 6- positions into other metabolic products of the eggs and embryos is also inhibited by dinitrocresol, particularly incorporation into the acid-insoluble fraction containing nucleoproteins.
A NEW PHOTOSENSITIVE PIGMENT OF THE EURYHALINE TELEOST, GILLICHTHYS MIRABILIS
Authors: Munz Frederick W.
Published: May 2004

Retinal extracts have been prepared from dark-adapted mudsuckers by treatment of retinal tissue or of isolated outer segments of the visual cells with digitonin solution. The extracts were examined spectrophotometrically and found to absorb light maximally between the wave lengths of 488 and 510 mµ, depending on the proportion of yellow impurities and light-sensitive pigment present. This photosensitive pigment was shown to be homogeneous by partial bleaching of the extracts with monochromatic light of various wave lengths from 390 to 660 mµ. The mudsucker pigment was specifically demonstrated not to be a mixture of rhodopsin and porphyropsin; the adequacy of the method used to analyze such mixtures was shown by performing a control experiment with an artificial mixture of bullfrog rhodopsin and carp porphyropsin.

Comparison of the hydroxylamine difference spectrum and of the absorption maximum of the purest retinal extract located the mudsucker photosensitive pigment maximum at 512 ± 1 mµ. Extraction of retinal tissue with a fat solvent after exposure to white light gave a preparation which after the addition of antimony chloride reagent developed the absorption band maximal near 664 mµ, which is characteristic of retinene1. If an hour intervened between exposure of the retinal tissue to light and extraction of the carotenoid, the antimony trichloride test gave a color band maximal at 620 mµ, characteristic of vitamin A1. No evidence of retinene2 or vitamin A2 was obtained. The euryhaline mudsucker has, therefore, a photosensitive retinal pigment with an absorption maximum halfway between the peaks of rhodopsins and of porphyropsins and belonging to the retinene1 system characteristic of rhodopsins. The pigment is therefore named a retinene1 pigment 512 of the mudsucker, Gillichthys mirabilis. It is uncertain whether this type of photosensitive pigment will be found in other euryhaline fishes.
THE EFFECT OF ULTRAVIOLET LIGHT ON THE PRODUCTION OF BACTERIAL VIRUS PROTEIN
Authors: Watanabe Itaru
Published: May 2004

The amount of phage-specific protein in T2-infected bacteria growing in a medium containing radiosulfur, S35, has been studied by measuring the radioactivity in specific antiphage serum precipitates of lysates. In the course of normal infection, non-infective phage antigen has been found to make its first intracellular appearance shortly before the end of the eclipse period, in agreement with the findings of Maaløe and Symonds with phage T4. No such phage antigen is produced either in bacteria infected with UV-inactivated T2 or in T2-infected bacteria whose survival as an infective center has been destroyed by UV irradiation during the early stages of the eclipse period. If the infected bacteria are UV-irradiated only at later stages of the eclipse period however, then phage antigenic protein continues to be synthesized in those infected cells in which DNA synthesis and, a fortiori, production of infective progeny have been almost completely suppressed. It is concluded from these results that once the mechanism for formation of phage-specific protein has been established within the infected cell under the influence of the parental DNA, synthesis of phage-specific protein can continue independently of the synthesis of phage DNA. The possibility that the phage DNA controls the specificity of the phage protein indirectly through substances other than DNA is discussed.
ADAPTATION OF BACILLUS MEGATHERIUM TO TERRAMYCIN (OXYTETRACYCLINE)
Authors: Northrop John H. ,   With the Technical Assistance of Marie King
Published: May 2004

B. megatherium cultures contain a few cells per hundred million which are able to grow in the presence of terramycin. Growth of the other cells is inhibited by the antibiotic with the result that the resistant cells overgrow the culture. The resistant cells are present in the culture, without contact with terramycin, and are able to grow in the presence of terramycin, without further modification.

The resistant cells are mutants of sensitive cells.
PROPERTIES OF PHYCOBILINS FROM PORPHYRA NAIADUM
Authors: Airth R. L. , Blinks L. R.
Published: May 2004

The phycobilin pigments were freshly extracted from Porphyra naiadum in the cold.

At least two types of phycoerythrin (I and II) can be distinguished by electrophoresis, chromatography, and spectral characteristics.

At pH 5.0 phycoerythrin II has a relatively large negative charge, while phycoerythrin I is nearly iso-electric. At pH 7.0, however, phycoerythrin I has the larger negative charge. Mobilities have been calculated by visual measurement of electrophoresis.

Phycoerythrin II can be converted to phycoerythrin I by storing at pH 7.0.

Chromatography indicates at least two types of phycocyanin as well.
EFFECTS OF METABOLIC INHIBITORS AND DRUGS ON ION TRANSPORT AND OXYGEN CONSUMPTION IN ISOLATED FROG SKIN
Authors: Huf Ernst G. , Doss Norma S. , Wills Joyce P.
Published: May 2004

Active ion (NaCl) transport across isolated frog skin is discussed in relation to sodium and potassium composition and to O2 consumption of skin. A distinction is made between processes in skin related to "unidirectional active ion transport" and processes related to "maintenance electrolyte equilibrium;" i.e., ionic composition of skin. Several metabolic inhibitors were found that could be used in separating maintenance electrolyte equilibrium from unidirectional active ion transport. Fluoroacetate (up to 1 x 10–2M/liter) did not affect maintenance electrolyte equilibrium, but severely diminished the rate of active ion transport. This could also be accomplished with azide and diethyl malonate when 1 x 10–3 molar concentrations were used. When applied in higher concentrations, these two inhibitors, and several others, diminished active ion transport, but this was associated with changes in maintenance electrolyte equilibrium (gain of Na+ by and loss of K+ from skin). Similar observations were made when skins were subjected to K+-deficient media. Mersalyl and theophylline, in low concentrations, stimulated active ion transport without leading to changes in maintenance electrolyte equilibrium. Inhibition of active ion transport was found accompanied by decrease, increase, and unaltered over-all O2 consumption, depending on the kind of chemical agent used. A provisional scheme of the mechanism of unidirectional active ion transport is proposed. It is conceived as a process of metabolically supported ion exchange adsorption, involving a carrier, forming complexes with K+ and Na+, a trigger, K+ ions, and two spatially separated metabolic pathways.
A MODIFIED CAPILLARY MICRORESPIROMETER
Authors: Bergersen F. J. , Merz B. E.
Published: May 2004

Modifications which enable simpler operation of the Cunningham-Barth-Kirk microrespirometer are described and an example of its use is quoted. Added advantages include easy positioning of indicator drop in the capillary and thermal equilibration at atmospheric pressure.
RESPIRATORY METABOLISM OF NORMAL AND DIVISIONLESS STRAINS OF CANDIDA ALBICANS
Authors: Ward John M. , Nickerson Walter J.
Published: May 2004

Respiration of a normal strain of Candida albicans was compared with that of a divisionless mutant which has a biochemical lesion such that metabolically generated hydrogen "spills over," during growth, for non-specific dye reduction. This waste is not at expense of growth, since both strains grow at essentially similar rates, nor at expense of respiration, since the mutant reduces oxygen more rapidly than the normal strain. Respiration in both strains is qualitatively similar, and seemingly unique among highly aerobic organisms in that it is not mediated by cytochrome oxidase. In resting cells of both strains, respiration is not only resistant to, but markedly stimulated by, high concentrations of cyanide, carbon monoxide, and azide. In contrast, growth of these yeasts is inhibited by low concentrations of cyanide and azide.

Cytochrome oxidase could not be detected in cell-free preparations; reduced cytochrome c was not oxidized by such preparations. Cytochrome bands could not be observed in thick cell suspensions treated with reducing agents. However, incorporation of superoptimal levels of zinc and iron into the culture medium resulted in growth of cells possessing distinct cytochrome bands; respiration of these cells remained insensitive to cyanide, monoxide, and azide, and the bands were maintained in a reduced form on oxygenation.

In the divisionless yeast, tetrazolium dyes compete with oxygen for reduction; this is not the case in the normal strain. The firmness with which hydrogen transfer is channeled in the latter for reduction of disulfide bonds (of importance in the division mechanism) and of oxygen, is contrasted with the lack of such control in the mutant.
FACILITATION BY PREVIOUS ACTIVITY IN A PACINIAN CORPUSCLE
Authors: Loewenstein Werner R.
Published: May 2004

A period of supernormal excitability is left by a propagated impulse in a Pacinian corpuscle. The increase in excitability is found 6 to 10 msec. after an impulse occurs in the corpuscle. Supernormality is produced by either mechanically elicited dromic impulses, or by electrically excited antidromic impulses. Generator potentials do not cause supernormality. Local potentials discharged spontaneously by the corpuscle, and which fall on the supernormal trail left by an antidromic impulse, become enhanced in amplitude, an eventually are turned into propagated dromic potentials. The supernormal period is interpreted as caused by a negative after-potential left at the first intracorpuscular node of Ranvier which outlasts both the recovery time of the firing level and that of the generator potential during the corpuscle's relative refractory period.
THE EFFECT OF ASCORBIC ACID OXIDATION ON THE INCORPORATION OF SULFATE BY SLICES OF CALF COSTAL CARTILAGE
Authors: Klebanoff S. J. , Dziewiatkowski D. D. , Okinaka G. J.
Published: May 2004

A marked inhibition of the incorporation of S35-sulfate by normal calf costal cartilage was produced by potassium ascorbate in the presence of catalytic amounts of cupric ions. The effect of the various components of the ascorbic acid oxidizing system (potassium ascorbate, cupric ions, cuprous ions, hydrogen peroxide, dehydroascorbic acid) was investigated. The results of experiments in which hydrogen peroxide, catalase, or sodium azide were used singly or in combination suggest that the inhibition produced by the ascorbic acid oxidizing system is due, to a considerable extent, to the production of hydrogen peroxide. Dehydroascorbic acid was also found to inhibit the incorporation of S35-sulfate by cartilage slices. However, the gradual fall in pH which resulted from the addition of dehydroascorbic acid could account to a large extent for the inhibitory effect observed because the incorporation of S35-sulfate by cartilage slices decreases sharply as the pH is lowered. The incorporation of S35-sulfate by cartilage slices is inhibited also by increasing the concentration of phosphate.
THE FUNCTION OF THE PROXIMAL SYNAPSES OF THE SQUID STELLATE GANGLION
Authors: Bryant S. H.
Published: May 2004

In the oxygenated excised squid (Loligo pealii) stellate ganglion preparation one can produce excitation of the stellar giant axons by stimulating the second largest (accessory fiber, Young, 1939) or other smaller preganglionic giant axons. Impulse transmission is believed to occur at the proximal synapses of the stellar giant axons rather than the distal (giant) synapses which are excited by the largest giant preaxon.

Proximal synaptic transmission is more readily depressed by hypoxia and can be fatigued independently of, and with fewer impulses than, the giant synapses. Intracellular recording from the last stellar axon at its inflection in the ganglion reveals both proximal and distal excitatory postsynaptic potentials EPSP's). The synaptic delay, temporal form of the EPSP, and depolarization for spike initiation were similar for both synapses.

If the proximal EPSP occurs shortly after excitation by the giant synapse it reduces the undershoot and adds to the falling phase of the spike. If it occurs later it can produce a second spike. Parallel results were obtained when the proximal EPSP's arrived earlier than the EPSP of the giant synapse.

In fatigued preparations it was possible to sum distal and proximal or two proximal EPSP's and achieve spike excitation.
AN ENZYMATIC ION EXCHANGE MODEL FOR ACTIVE SODIUM TRANSPORT
Authors: Koblick Daniel C.
Published: May 2004

An enzymatic ion exchange model for active sodium transport is described. Kinetic equations relating net flux to time, and to concentration difference across the actively transporting membrane are derived. The second of these equations is tested, using the isolated frog skin in the "short-circuit" apparatus of Ussing. Reasonable linearity, as predicted by this equation, is observed.

The passive permeability coefficient for Na+, is calculated as 5.3 x 10-4 ± 5.3 x 10-4 cm./hr. If cholinesterase is assumed to be the enzyme responsible for transport, the activity required to account for the observations reported here is 17.7 x 10-4 mmoles/cm.2/hr.
ELECTROKINETIC MEMBRANE PROCESSES IN RELATION TO PROPERTIES OF EXCITABLE TISSUES
Authors: Teorell Torsten
Published: May 2004

A quantitative theory is presented for the behavior of a membrane-electrolyte system subject to an electric current flow (the "membrane oscillator"). If the membrane is porous, carries "fixed charges," and separates electrolyte solutions of different conductances, it can be the site of repetitive oscillatory changes in the membrane potential, the membrane resistance, and the hydrostatic pressure difference across the membrane. These events are accompanied by a pulsating transport of bulk solutions. The theory assumes the superposition of electrochemical and hydrostatic gradients and centers round the kinetics of resistance changes within the membrane, as caused by effects from diffusion and electro-osmotic fluid streaming. The results are laid down in a set of five simple, basic expressions, which can be transformed into a pair of non-linear differential equations yielding oscillatory solutions. A graphical integration method is also outlined (Appendix II).

The agreement between the theory and previous experimental observations is satisfactory. The applied electrokinetic concepts may have importance in relation to analyses of the behavior of living excitable cells or tissues.
ELECTROPHYSIOLOGY OF ELECTRIC ORGAN IN GYMNOTUS CARAPO
Authors: Bennett Michael V. L. , Grundfest Harry
Published: May 2004

The electric organ of G. carapo is formed by linearly arrayed electroplaques which lie in four tubes on each side of the fish. In one tube the electroplaques are innervated on their rostral surfaces, in the others on the caudal. Both surfaces of each electroplaque produce spikes, and either can be excited alone by a suitably oriented externally applied stimulating current. The innervated surface, however, has a lower threshold, and in the normal organ activity, which is a continuous discharge at 35 to 60/sec., it is always fired first by the large neurally evoked postsynaptic potential. The spike of the innervated face then fires the opposite face. The potential recorded external to the innervated face is initially negative and becomes positive when the other face fires. The potential outside the other face is inverted. The p.s.p.'s are electrically inexcitable, have short duration, and are augmented by hyperpolarization. A single electroplaque is innervated by several nerve fibers, which produce summative p.s.p.'s. Homosynaptic facilitation of p.s.p.'s is common. The synapses are cholinoceptive. The organ discharge begins with synchronized activity in the rostrally innervated electroplaques. After a brief interval, the electroplaques in the other three tubes fire. The organ discharge therefore is triphasic, resulting from the summation of the two diphasic components that are oppositely directed and asynchronous. Observations on the sensory role of the organ are included.