bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECT OF ORGANIC IONS ON THE MEMBRANE POTENTIAL OF NERVES
Authors: Wilbrandt W. 
Published: May 2004

1. The effect of osmotic pressure on the nerve resting potential of frog sciatic nerve is in accordance with the assumption of a membrane potential; increased osmotic pressure raises, decreased osmotic pressure lowers the potential.
2. The potential of crab nerves is affected by organic and inorganic cations in the approximate series:
Rb &gt; K = diamylamine &gt; dibutylamine &gt; guanidine &gt; tetraethylamine &gt; diethylamine = dimethylamine &gt; dipropylamine &gt; tetramethylamine = choline = Na = Li.
3. The response of the potential to the series of dialkylamines (first decrease, then increase of response ascending in the series) is best understood by the assumption that the nerve membrane is a porous structure.
4. With respect to these salts as well as to other organic cations the dried collodion membrane as a model of a porous membrane shows a striking parallelism to the nerve membrane.
5. Both inorganic and organic anions (NO3, SCN, acetate, propionate, butyrate, lactate, pyruvate) have a definite, if slight, effect in raising the potential of crab nerves. This effect of anions indicates that the nerve membrane is not completely anion impermeable.
6. The effect of organic ions is, with certain restrictions, reversible. Its possible relation to the resting potential and to the after potentials of the electrical disturbance is discussed.
7. The response of the myelinated sciatic nerve of the frog and of the non-myelinated nerve of the spider crab show considerable agreement. There are some definite differences which are, however, not necessarily due to differences of the cell membranes involved, but may be ascribed to the difference of ionic conditions in Ringer and sea water.
IMMUNOLOGICAL STUDIES ON PEPSIN AND PEPSINOGEN
Authors: Seastone C. V. , Herriott R. M. 
Published: May 2004

1. Alkali (pH 7.6)-denatured pepsins from swine, cattle, and guinea pigs precipitate in swine pepsin antiserum. Similarly treated pepsins from the rabbit, chicken, and shark do not.
2. Pepsin antisera react with both pepsin and pepsinogen, but do not react with the serum proteins from the homologous species.
3. Pepsinogen antisera react with pepsinogen, but not with twice crystallized pepsin, nor with the serum proteins from the homologous species. Positive reactions between activated pepsinogen and pepsinogen antiserum have been observed. It was possible to remove the reacting material from either the pepsinogen or the activated pepsinogen mixture.
4. Antisera made with serum proteins do not react with the homologous pepsin or pepsinogen.
THE INFLUENCE OF LIGHT ADAPTATION ON SUBSEQUENT DARK ADAPTATION OF THE EYE
Authors: Hecht Selig , Haig Charles , Chase Aurin M. 
Published: May 2004

The course of dark adaptation of the human eye varies with the intensity used for the light adaptation which precedes it. Preadaptation to intensities below 200 photons is followed only by rod adaptation, while preadaptation to intensities above 4000 photons is followed first by cone adaptation and then by rod adaptation.
With increasing intensities of preadaptation, cone dark adaptation remains essentially the same in form, but covers an increasing range of threshold intensities. At the highest preadaptation the range of the subsequent cone dark adaptation covers more than 3 log units.
Rod dark adaptation appears in two types—a rapid and a delayed. The rapid rod dark adaptation is evident after preadaptations to low intensities corresponding to those usually associated with rod function. The delayed rod dark adaptation shows up only after preadaptation to intensities which are hundreds of times higher than those which produce the maximal function of the rods in flicker, intensity discrimination, and visual acuity. The delayed form remains essentially constant in shape following different intensities of preadaptation. However, its time of appearance increases with the preadaptation intensity; after the highest preadaptation, it appears only after 12 or 13 minutes in the dark.
These two modes of rod dark adaptation are probably the expression of two methods of formation of visual purple in the rods after its bleaching by the preadaptation lights.
DO MELANOPHORE NERVES SHOW ANTIDROMIC RESPONSES?
Authors: Parker G. H. 
Published: May 2004

1. In Fundulus heteroclitus the dispersing melanophore nerve fibers have a relatively high threshold for faradic stimulation and a low one for stimulation by cutting. When they are protected from the competing action of the concentrating fibers, they show through the responses of their melanophores well marked antidromic activities which can also be seen to a slight degree even where the concentrating fibers are active.
2. The concentrating melanophore nerve fibers in this fish have a relatively low threshold for faradic stimulation and a high one for stimulation by cutting. They also exhibit clear antidromic responses as shown by their associated melanophores.
STUDIES ON THE DIFFUSION EFFECT UPON IONIC DISTRIBUTION
Authors: Teorell Torsten 
Published: May 2004

The aim of this paper is to present confirmation of the theory of the diffusion effect. By diffusion effect is understood a redistribution of the ions in a system where a continuous diffusion of one electrolyte is going on, which results in a steady state showing accumulation and impoverishment of certain ions.
Some typical experiments are recorded and discussed. The results are found in satisfactory agreement with the theory: this can be demonstrated in several ways.
The importance of considering activity changes is pointed out. Water migration and the diffusion membrane probably have no appreciable influence upon the diffusion effect under the conditions of these experiments.
The diffusion effect may have biological analogies.
THE EFFECT OF HYDROGEN ION CONCENTRATION UPON THE INDUCTION OF POLARITY IN FUCUS EGGS
Authors: Whitaker D. M. , Lowrance E. W. 
Published: May 2004

1. When a Fucus egg develops near one end in a close fitting capillary tube of pyrex glass or silica (quartz), diffusion of substances passing to and from the egg is more impeded on the side of the egg toward the far end of the tube.
2. The egg therefore develops in a gradient of its own diffusion products, and of oxygen tension.
3. More than 600 eggs have been reared, each near one end in a capillary, in sea water at various regulated and measured pH values.
4. When the medium, which is initially homogeneous inside and outside the capillary, is initially at pH 6.5 to 7.6, nearly all of the eggs develop rhizoid protuberances on the sides of the eggs toward the far ends of the capillaries. This is on the sides of the eggs where the concentration of substances diffusing from the eggs is greatest.
5. The polarity and developmental pattern of the egg is thus determined either by a concentration gradient of products diffusing from it, or by a gradient of oxygen tension. The former interpretation is favored.
6. This is regarded as an extension of earlier observations that rhizoid protuberances form on the sides of two neighboring eggs in the direction of the neighbor if the sea water is acidified.
7. It appears hardly possible that a mitogenetic effect could be responsible for the response of an egg to its own diffusion gradients.
8. When the medium is made more basic, the percentage of the eggs which form rhizoid protuberances toward the far end of the tube decreases to about 20 or 25 per cent between pH 8.1 and 8.6. The response of the egg to the gradients which it produces is thus statistically reversed. The determination of the polarity of the eggs by the diffusion gradients does not become as complete in alkalinized as in acidified sea water.
9. When the pH of the sea water is elevated to 9.1 or 9.2, salts precipitate out. The type of development is altered and the control of the diffusion gradients over the polarity of the eggs decreases.
THE RELATION BETWEEN VISUAL ACUITY AND ILLUMINATION
Authors: Shlaer Simon 
Published: May 2004

1. An apparatus for measuring the visual acuity of the eye at different illuminations is described. The test object is continuously variable in size and is presented at a fixed distance from the eye in the center of a 30° field. Observation of the field is through an artificial pupil. The maximum intensity obtainable is more than enough to cover the complete physiological range for the eye with white light though only 110 watts are consumed by the source. Means for varying the intensity over a range of 1:1010 in small steps are provided.
2. The relation of visual acuity and illumination for two trained observers was measured, using two different types of test object, a broken circle and a grating. The measurements with both test objects show a break at a visual acuity of 0.16, all values below that being mediated by the rods and those above by the cones. The grating gives higher visual acuities at intensities less than about 30 photons and lower visual acuities above that. The maximum visual acuity attainable with the grating under the same conditions is about 30 per cent lower than that with the C. It is shown that the limiting factor in the resolution of the eye for the grating is the diameter of the pupil when it is less than 2.3 mm. and the size of the central cones when the pupil is larger than that. The value of the diameter of the cone derived on that basis from the visual acuity data agrees with that derived from direct cone count in a unit of area.
3. The data for the cones made with both test objects are adequately described by one and the same form of the stationary state equation derived by Hecht for the photoreceptor system. This fact, together with certain considerations about the difference in the nature of the two test objects with regard to the resolvable area, leads to the conclusion that detail perception is a function of a distance rather than an area. All the data for the rods can likewise be described by another variety of the same equation, although the data are too fragmentary to make the choice of the form as certain as might be desired.
TRANSVERSE ELECTRIC IMPEDANCE OF NITELLA
Authors: Curtis Howard J. , Cole Kenneth S. 
Published: May 2004

Alternating current measurements have been taken on single Nitella cells over a frequency range from 30 to 2,500,000 cycles per second with the current flow perpendicular to the axis of the cell. The measuring cells were so constructed that electrolytes of any desired concentration could be circulated during the course of the measurements. The cellulose wall which surrounds the cell is found to play an important part in the interpretation of the results obtained. In a mature cell, this cellulose has a specific resistance of about 1000 ohm cm. which is independent of the medium in which the cell is suspended. The thickness of the wall is computed to be about 10 µ. The cell membrane is found to be virtually non-conducting, and to have a capacity of 0.94 µf./cm.2 ± 10 per cent and a phase angle of 80° ± 4°.
The specific resistances of the sap were difficult to compute from data on living cells and were unsatisfactory because they were very much dependent upon the medium, while measurements on extracted sap gave 58 ohm cm. ± 8 per cent which was independent of the medium. There are indications that the chloroplasts have impedance properties similar to those of living cells.
STUDIES ON ENZYMATIC HISTOCHEMISTRY
Authors: Glick David 
Published: May 2004

The activity-pH relationship for choline esterase from horse serum, gastric mucosa of the pig, and cat brain was investigated, and an optimum was observed at pH 8.5 in each case.
A micro method for the determination of choline esterase was developed capable of measuring the hydrolysis down to the order of that given by 1 x 10–8 mol of ester.
CRITICAL ILLUMINATION AND FLICKER FREQUENCY, AS A FUNCTION OF FLASH DURATION: FOR THE SUNFISH
Authors: Crozier W. J. , Wolf E. , Zerrahn-Wolf G. 
Published: May 2004

From the relations between critical illumination in a flash (Im) and the flash frequency (F) for response of the sunfish to visual flicker when the proportion of light time to dark time (tL/tD) in a flicker cycle is varied at one temperature (21.5°) the following results are obtained:
At values of tL/tD between 1/9 and 9/1 the F - log Im curves are progressively shifted toward higher intensities and lower Fmax.. Fmax. is a declining rectilinear function of the percentage of the flash cycle time occupied by light.
The rod and the cone portions of the flicker curve are not shifted to the same extent.
The cone portion and the rod region of the curve are each well described by a probability integral. In terms of F as 100 F/Fmax. the standard deviation of the underlying frequency distribution of elemental contributions, summed to produce the effect proportional to F, is independent of tL/tD.
The magnitude of log Im at the inflection point (r'), however, increases rectilinearly with the percentage light time in the cycle.
The proportionality between Im and σII1 is independent of tL/tD.
These effects are interpreted as consequences of the fact that the number of elements of excitation available for discrimination of flicker is increased by increasing the dark interval in a flash cycle. Decreasing the dark interval has therefore the same kind of effect as reducing the visual area, and not that produced by decreasing the temperature.
THE CONCENTRATION EFFECT WITH VALONIA: POTENTIAL DIFFERENCES WITH DILUTED POTASSIUM-RICH SEA WATERS
Authors: Damon E. B. 
Published: May 2004

The concentration effect with sea waters containing more than the normal amount of potassium has been studied in Valonia macrophysa. This was done by comparing the initial changes in P.D. across the protoplasm when natural sea water bathing the cell was replaced by various isotonic dilutions of KCl-rich sea waters.
With small dilutions of KCl-rich sea waters, the P.D.-time curves are of the same form as with the undiluted solution, exhibiting the fluctuations characteristic of KCl-rich solutions. This indicates that with these solutions K+ enters Valonia protoplasm and plays an important part in the P.D. The value of the initial rise in P.D. decreases with increasing dilution.
With high dilutions of KCl-rich sea waters, the P.D.-time curves are of quite different shape, resembling the curves with diluted natural sea water; the P.D. is practically independent of small changes in the concentration of potassium, and increases with increasing dilution. That is, with these higher dilutions, the sign of the concentration effect is reversed, becoming the same as with diluted natural sea water.
The greater the concentration of KCl in the undiluted sea water, the higher is the critical dilution at which K+ ceases to influence the P.D.
For a wide range of sea waters containing both KCl and NaCl, it is shown that the concentration effect above the critical dilution is determined solely by the activity of NaCl in the external solution. It is concluded that with dilute natural sea water and with high dilutions of KCl-rich sea waters we have to do with a diffusion potential, involving only the Na+ and Cl- ions, which are diffusing out from the vacuole.
A quantitative relation between the composition of the sea water and the critical dilution has been deduced from the classical theory of the diffusion of electrolytes. It is shown that with dilutions less than this critical value the diffusion of K+ in the outer non-aqueous layer of the protoplasm is directed inward; hence K+ enters the protoplasm from these solutions. With dilutions greater than the critical value, the diffusion of K+ in this layer is directed outward; hence K+ does not enter the protoplasm.
Since the P.D. shows no evidence of this outward diffusion of K+, it is concluded that the amount of K+ ordinarily present in the protoplasm is too small to produce any lasting electrical effect, and that the outward diffusion of K+ from the vacuole is prevented by the mechanism responsible for the accumulation of KCl in the cell sap.
ISOLATION, CRYSTALLIZATION, AND PROPERTIES OF SWINE PEPSINOGEN
Authors: Herriott Roger M. 
Published: May 2004

1. A method is described for the preparation of pepsinogen from swine gastric mucosae which consists of extraction and fractional precipitation with ammonium sulfate solutions followed by two precipitations with a copper hydroxide reagent under particular conditions. Crystallization as very thin needles takes place at 10°C., pH 5.0 and from 0.4 saturated ammonium sulfate solution containing 3–5 mg. protein nitrogen per milliliter.
2. Solubility measurements, fractional recrystallization, and fractionation experiments based on separation after partial heat or alkali denaturation and after partial reversal of heat or alkali denaturation failed to reveal the presence of any protein impurity.
3. The properties of the enzymatically inactive pepsinogen were studied and compared with the properties of crystalline pepsin. The properties of pepsinogen which are similar to those of pepsin are: molecular weight, absorption spectrum, tyrosine-tryptophane content, and elementary analysis. The properties in which they differ are: enzymatic activity, crystalline form, amino nitrogen, titration curve, pH stability range, specific optical rotation, isoelectric point, and the reversibility of heat or alkali denaturation.
4. Conversion of pepsinogen into pepsin at pH 4.6 was found to be autocatalytic; i.e., the pepsin formed catalyzes the reaction. Conversion of pepsinogen into pepsin is accompanied by the splitting off of a portion of the molecule containing 15–20 per cent of the pepsinogen nitrogen.
CALCULATIONS OF BIOELECTRIC POTENTIALS
Authors: Hill S. E. , Osterhout W. J. V. 
Published: May 2004

Cells of Nitella have been studied which behave differently from those described in earlier papers. They show unexpectedly large changes in P.D. with certain concentrations of KCl. This is due to the production of action currents (these are recorded at the spot where KCl is applied).
A method is given for the separate evaluation of changes of P.D. due to partition coefficients and those due to mobilities.
A new amplifier and an improved flowing contact are described.
ELECTRIC IMPEDANCE OF FERTILIZED ARBACIA EGG SUSPENSIONS
Authors: Cole Kenneth S. , Spencer Joseph M. 
Published: May 2004

From the low frequency alternating current impedance and the volume concentrations of suspensions of Arbacia eggs, it is shown that the high resistance membrane is either at or very near the plasma membrane for both unfertilized and fertilized eggs, and that the specific resistances of the perivitelline space and fertilization membrane are not greatly different from that of sea water. The effect of the capacity element which appears after fertilization at intermediate frequencies is considerably less than in the earlier experiments on Arbacia and Hipponoë eggs.
These findings indicate that the fertilization membrane does not have the high capacity previously attributed to it and that the increase in membrane capacity takes place at or near the plasma membrane.
STUDIES IN THE PHYSICAL CHEMISTRY OF AMINO ACIDS, PEPTIDES, AND RELATED SUBSTANCES
Authors: Cohn Edwin J. , McMeekin Thomas L. , Blanchard Muriel H. 
Published: May 2004

1. As an introduction to the relations that obtain in biochemical systems containing several components, some ionic, some dipolar ionic, the solubility of cystine has been investigated in the presence of glycine and neutral salts.
2. Both glycine and sodium chloride increase cystine solubility at all concentrations. The interaction between cystine and ions is, however, diminished with increase in glycine concentration, and the interaction between cystine and glycine with increase in ionic strength.
3. Sodium sulfate also increases the solubility of cystine, but at concentrations greater than one molal its solvent action is smaller than its salting-out effect, which is greater at all concentrations than that of sodium chloride, and greater the higher the glycine concentration.
4. These interactions are defined by an equation giving the solubility ratio of cystine in terms of salting-out constants, constants related to the electric moments of cystine, and to the ionic strength and dielectric constant of the solution.
5. The higher the concentration of glycine and therefore the dielectric constant of the solution, the smaller that part of the interaction between ions and dipolar ions which depends upon Coulomb forces and the greater appears the salting-out effect.
6. Conversely, the greater the ionic strength and the salting-out effect the smaller the interaction between dipolar ions in solution.
THE ACCUMULATION OF ELECTROLYTES
Authors: Jacques A. G. 
Published: May 2004

When cells of Valonia macrophysa were placed in hypertonic sea water, the concentration of halide and of nitrate increased, and the sum of halide + nitrate became 0.05 M greater inside than outside, which is about the same difference as is found in cells in normal sea water.
In ordinary sea water the ratio of halide to nitrate is 80,000 to 1. When this was changed by substituting nitrate for halide so that the concentration of halide was 1.75 times that of nitrate the rate of entrance of halide was 1.68 times that of nitrate in 276 hours and the ratio of halide to nitrate in the sap decreased from 38 to 18.5.
No halide came out in exchange for entering nitrate. The retention of chloride may well be due to the fact that even when the halide concentration of the sea water is reduced as low as 0.4 M, there is still an inwardly directed activity gradient of sodium chloride.
THE EFFECT OF HYDROGEN ION CONCENTRATION UPON THE INDUCTION OF POLARITY IN FUCUS EGGS
Authors: Whitaker D. M. 
Published: May 2004

1. Gradients of hydrogen ion concentration across Fucus eggs growing in sea water determine the developmental polarity of the embryo.
2. Gradients may determine polarity even if removed before the morphological response begins.
3. The rhizoid forms on the acid side of the egg unless this is too acid, in which case it develops on the basic side of the egg.
4. Since gradients of hydrogen ion concentration in sea water produce gradients of CO2 tension, as a result of chemical action on the carbonate buffer system, it is not proven whether the physiological effects are due to the hydrogen ions, or to the CO2 which they produce in the medium.
5. The developmental response of the eggs to gradients of hydrogen ion (or CO2) concentration provides an adequate but not an exclusive explanation of the group effect in Fucus.
6. Hydrogen ions may exert their effect by activating growth substance. Hydrogen ions or CO2 probably also affect the underlying rhizoid forming processes in other ways as well.
THE ELECTROPHORETIC MOBILITY OF HUMAN ERYTHROCYTES—WHOLE CELLS, GHOSTS, AND FRAGMENTS
Authors: Byler W. H. , Rozendaal H. M. 
Published: May 2004

The electrophoretic mobility of human red cell ghosts decreases in the presence of chicken serum. The decrease is not directly due to the presence of adsorbed material but to a change which is catalyzed by the foreign substance. It is suggested that abnormal serum materials resulting from disease may serve as catalysts.
Fragments of broken cells have the same mobility as whole cells at first, then decrease even in pure salt suspension, while the whole cells remain essentially unchanged for hours.
The results suggest that the slow change of whole cells, the change of ghosts in the presence of foreign serum, and the change of fragments are all manifestations of the same modification of structure or composition of the cell surface.