bluuebunny/crossref_metadata_2025_split huggingface dataset:
CRYSTALLINE PEPSIN
Authors: Northrop John H. 
Published: May 2004

1. A method has been described for isolating a crystalline protein with high proteolytic activity from bovine gastric juice by means of precipitation with magnesium sulfate and fractionation of the precipitate with acetone and magnesium sulfate.
2. The crystalline protein obtained in this way has the same crystalline form, optical activity, and specific activity, as determined by a number of methods, as does the crystalline protein previously isolated from swine gastric mucosa.
3. The solubility of the two preparations, however, is additive so that they are different although very closely related proteins.
STIMULATION BY THE MINERAL ACIDS, HYDROCHLORIC, SULFURIC, AND NITRIC, IN THE SUNFISH EUPOMOTIS
Authors: Cole William H. , Allison J. B. 
Published: May 2004

1. The stimulating efficiency of hydrochloric, sulfuric, and nitric acids has been measured in the sunfish Eupomotis gibbosus, by a method which reduces experimental errors to a minimum.
2. The results show that stimulation by these acids is primarily dependent upon the (H+) produced in the animal's aquatic environment, and that the reaction time is a logarithmic function of the (H+) within the range tested expressed by the equation: (RT–5) = –4.3 log (H+ x 104) + 9.118.
3. Any effect of the chloride, sulfate, and nitrate ions must itself be measured by the (H+).
4. Variation in the reaction time is also a logarithmic function of the (H+), and the percentage variation is independent of the (H+) over the range tested.
5. Freshly collected fish show a lower threshold for stimulation as determined by the (H+) than do fish adapted to laboratory conditions, but relatively the reaction times of the two groups are the same.
QUANTITATIVE ANALYSIS OF RESPONSES FROM LATERAL-LINE NERVES OF FISHES. II
Authors: Hoagland Hudson 
Published: May 2004

1. The lateral-line nerves of trout as well as those of catfish are found to discharge impulses spontaneously at a high frequency.
2. The frequency of nerve impulse discharge is measured as a function of the number of participating receptor groups (lateral-line sense organs). A quantitative analysis is made of the contribution to the total response made by each group of sense organs.
3. An analysis of the variability of the response is presented which makes it possible to estimate quantitatively the longitudinal extent of damage to the neuromasts due to surgical manipulation.
4. A method is described for recording the response of a single nerve fiber in the lateral-line trunk.
5. The frequency of the spontaneous discharge from the lateral-line nerve trunk when plotted as a function of temperature according to the Arrhenius equation yields a temperature characteristic of approximately 5000 calories.
6. The variability of the frequency of response as a function of temperature indicates the existence of temperature thresholds for the spontaneous activity of the neuromasts.
7. A possible basis for the spontaneous activity is considered.
It is pointed out that the lateral-line system may serve as a model of the Purkinje cells of the cerebellum.
AN ATTEMPT AT PEPTIC SYNTHESIS OF INSULIN
Authors: Fisher A. M. , Scott D. A. 
Published: May 2004

1. Synthesis of plastein from the products of peptic hydrolysis of small quantities of egg albumin can be demonstrated with amorphous or crystalline pepsin.
2. Synthesis of plastein from the products of peptic hydrolysis of amorphous or crystalline insulin can be demonstrated with amorphous or crystalline pepsin.
3. The plastein synthesised by pepsin from the products of peptic hydrolysis of insulin is physiologically inactive.
4. The plastein formed in the insulin experiments could not be crystallised by the methods used for the crystallisation of insulin.
5. The physiological activity of insulin is not destroyed by repeated freezing (at about –50°C.) and melting of an aqueous or an alcoholic solution of this hormone.
6. No marked decrease in the physiological activity of insulin after incubation at 37°C. with pepsin at pH 4.0, in dilute or concentrated solutions, was detected.
THE DIFFUSION COEFFICIENT OF CRYSTALLINE TRYPSIN
Authors: Scherp Henry W. 
Published: May 2004

The diffusion coefficient of crystalline trypsin in 0.5 saturated magnesium sulfate at 5°C. is 0.020 ±0.001 cm.2 per day, corresponding to a molecular radius of 2.6 x 10–7 cm.
The rate of diffusion of the proteolytic activity is the same as that of the protein nitrogen, indicating that these two properties are held together in chemical combination and not in the form of an adsorption complex.
THE RATE OF OXYGEN UTILIZATION BY YEAST AS RELATED TO TEMPERATURE
Authors: Stier T. J. B. 
Published: May 2004

Suspensions of the yeast Saccharomyces cerevisiae gave reproducible rates of O2 uptake over a period of 6 months. The relation of rate of consumption of O2 to temperature was tested over a wide range of temperatures, and the constant in the formulation of the relationship is found to be reproducible. The values of this constant (µ) have been obtained for five separate series of experiments by three methods of estimation. The variability of µ has the following magnitudes: the average deviation of a single determination expressed as per cent of the mean is ±2 per cent in the range 30–15°, and ±0.8 per cent in the range 15–3°C. This constancy of metabolic activity measured as a function of temperature can then be utilized for more precise investigations of processes controlling the velocity of oxidations of substrates, and of respiratory systems controlled by intracellular respiratory pigments.
The data plotted according to the Arrhemus equation give average values of the constant µ as follows: for the range 35–30°, µ = 8,290; 30–15°, µ = 12,440 ±290; 15–3°, µ = 19,530 ±154. The critical temperatures are at 29.0° and 15.7°C.
A close similarity exists between these temperature characteristics (µ) and values in the series usually obtained for respiratory activities in other organisms. This fact supports the view that a common system of processes controls the velocities of physiological activities in yeast and in other organisms.
THE VIOLOGEN INDICATORS
Authors: Michaelis L. , Hill Edgar S. 
Published: May 2004

The tabulation gives the normal potentials of the various indicators at 30°C.; referred to the normal hydrogen electrode, the accuracy is estimated to be ±0.002 volt.
Normal potentials of the viologens at 30°C.:
Methyl viologen –0.446 volts
Ethyl viologen –0.449 volts
Betaine viologen –0.444 volts
Benzyl viologen –0.359 volts
Supposing some solution brings about a coloration of one of these indicators to the extent of A per cent of the maximum color, the oxidation-reduction potential of this solution is E = Eo – 0.06 log
See PDF for Equation
where Eo is the normal potential according to the above tabulation. This normal potential is independent of pH.
MOVEMENT IN THE CYANOPHYCEAE
Authors: Burkholder Paul R. 
Published: May 2004

The effect of pH upon the velocity of translatory movement of Oscillatoria formosa Bory in inorganic culture solutions was determined.
Unhindered movement occurred in the range of about pH 6.4 to 9.5. Above and below these limits inhibition was marked.
In the unfavorable acid and alkaline ranges inhibition was progressive with exposure time; in the favorable range continuous movement was maintained for 24 hours.
STIMULATION BY MINERAL AND FATTY ACIDS IN THE BARNACLE BALANUS BALANOIDES
Authors: Cole William H. , Allison J. B. 
Published: May 2004

1. Stimulation in the rock barnacle Balanus balanoides by hydrochloric, sulfuric, and nitric acids, and by the first seven members of the normal aliphatic acid series has been studied. The hydrogen ion concentrations of the solutions tested varied from 3.2 x 10–8 to 5.889 x 10–6. The criterion of response was percentage closure in groups of individuals, recorded at 1 minute intervals until maximum closure occurred.
2. The intensity of stimulation by these acids is proportional to the effects of two forces, one related to the change in the (H+), and the other to the field of force around the anion of the acid added to the environment.
3. A preliminary interpretation of the results led to the development of the following expression which fits approximately the data obtained at the end of 4 minutes:
Per cent closure = 100 – 100e–0.1z+(0.003125)2–0.1z+(0.003125)2n(z–0.4)
where z is the (H+) x 107 and n is the number of carbon atoms (if present) in the anion of the acid. This equation assumes that the anions of the mineral acids enter into the reaction stoichiometrically, and emphasizes the difference in the fields of force around the anion of the fatty acids, a difference which is correlated with the length of the carbon chain.
4. A further analysis of the data revealed the presence of three or more receptor groups which appeared to be differentially affected by forces originating from the anions of the acids.
5. The order of stimulating efficiency for the mineral acids was found to be: HCl&gt;H2SO4&gt;HNO3.
6. The order of stimulating efficiency for the fatty acids was found to be: heptylic&gt;caproic&gt;valeric&gt;butyric = acetic&gt;propionic = formic.
REACTIONS OF VALONIA AND OF HALICYSTIS TO COLLOIDS
Authors: East E. M. , White Benjamin 
Published: May 2004

From the results of these tests it is clear that both Halicystis and Valonia have a high degree of tolerance for animal peptone, and a very high degree of tolerance for animal proteose and for egg albumen. The products of bacterial growths fostered by these proteins have a deleterious effect upon both species of algae; but, if it were possible to prevent bacterial growth entirely and at the same time supply proper food, it is probable that Halicystis and Valonia would show normal growth indefinitely in the presence of these three colloids. This is not true where exposure is made to yeast nucleic acid dissolved in sea water containing 0.00093 gm. per cc. of NaOH. Valonia is markedly less tolerant of this medium (perhaps of NaOH rather than the colloid used) than Halicystis. Such differential effects, however, reach a high point in the case of the solutions of diphtheria toxin and of edestin. Halicystis has a very high tolerance for diphtheria toxin, and Valonia a very low tolerance. In the case of edestin, the relationship is reversed. Here Halicystis has a very low tolerance, and Valonia a very high tolerance. In fact, it may be said that diphtheria toxin has no appreciable effect upon Halicystis, and edestin a very slight effect upon Valonia; while diphtheria toxin is extremely toxic to Valonia, and edestin is extremely toxic to Halicystis. We can offer no suggestions, at present, as to the way in which these effects are produced.
It is probable that the very thin protoplasmic layer of these species, which is certainly no thicker than 8µ, is sufficient to obstruct the passage of proteins having large molecules, like egg albumen, with a degree of efficiency that is extraordinary. In the tests we have reported, areas of from 20 sq. cm. to 40 sq. cm. have been submitted to the action of a relatively high concentration of egg albumen for several days without permitting the passage of sufficient amounts to give definable tests either with Spiegler's or with Tanret's method,— presumably less than 1 part in 250,000.
In the tests of the proteins having much smaller molecules (though the size may not be the explanation), there is some probability that the membranes exhibit a little permeability. The peptone and the proteose of animal origin, or biuret-positive substances derived from them, apparently pass the protoplasmic membranes occasionally in quantities sufficient to give biuret tests. The most probable case of protein passage, however, was that of the proteose of the scarlet runner bean, where specific detection of less than 1 part per 80,000 was possible. In this instance the proteose appeared to pass membranes that were healthy and were functioning normally. But since the cells of the algae had to be destroyed in making the tests, one cannot maintain this point. All one can say is that protein passage was indicated in carefully examined cells of both species, where no breaks in the protoplasmic membrane were discernible, and where samples of the treated cells behaved normally after treatment.
SWELLING OF ERYTHROCYTES IN SOLUTIONS OF AMMONIUM SALTS
Authors: Schiödt E. 
Published: May 2004

Two rather simple equations have been derived, which make it possible to express in a single number the result of a series of determinations of the volume of erythrocytes swelling in solutions of ammonium salts.
In all experiments made with several combinations of different concentrations of permeating and non-permeating salts, the curves calculated from the equations have covered the points found by experiment.
PROTOPLASMIC POTENTIALS IN HALICYSTIS
Authors: Blinks L. R. 
Published: May 2004

The nature and origin of the large "protoplasmic" potential in Halicystis must be studied by altering conditions, not only in external solutions, but in the sap and the protoplasm itself. Such interior alteration caused by the penetration of ammonia is described. Concentrations of NH4Cl in the sea water were varied from 0.00001 M to above 0.01 M. At pH 8.1 there is little effect below 0.0005 M NH4Cl. At about 0.001 M a sudden reversal of the potential difference across the protoplasm occurs, from about 68 mv. outside positive to 30 to 40 mv. outside negative. At this threshold value the time curve is characteristically S-shaped, with a slow beginning, a rapid reversal, and then an irregularly wavering negative value. There are characteristic cusps at the first application of the NH4Cl, also immediately after the reversal.
The application of higher NH4Cl concentrations causes a more rapid reversal, and also a somewhat higher negative value. Conversely the reduction of NH4Cl concentrations causes recovery of the normal positive potential, but the threshold for recovery is at a lower concentration than for the original reversal. A temporary overshooting or increase of the positive potential usually occurs on recovery. The reversals may be repeated many times on the same cell without injury.
The plot of P.D. against the log of ammonium ion concentration is not the straight line characteristic of ionic concentration effects, but has a break of 100 mv. or more at the threshold value. Further evidence that the potential is not greatly influenced by ammonium ions is obtained by altering the pH of the sea water. At pH 5, no reversal occurs with 0.1 M NH4Cl, while at pH 10.3, the NH4Cl threshold is 0.0001 M or less. This indicates that the reversal is due to undissociated ammonia.
The penetration of NH3 into the cells increases both the internal ammonia and the pH. The actual concentration of ammonium salt in the sap is again shown to have little effect on the P.D. The pH is therefore the governing factor. But assuming that NH3 enters the cells until it is in equilibrium between sap and sea water, no sudden break of pH should occur, pH being instead directly proportional to log NH3 for any constant (NH4) concentration. Experimentally, a linear relation is found between the pH of the sap and the log NH3 in sea water. The sudden change of P.D. must therefore be ascribed to some system in the cell upon which the pH change operates. The pH value of the sap at the NH3 threshold is between 6.0 and 6.5 which corresponds well with the pH value found to cause reversal of P.D. by direct perfusion of solutions in the vacuole.
ANESTHESIA PRODUCED BY DISTILLED WATER
Authors: Osterhout W. J. V. , Hill S. E. 
Published: May 2004

Cells of Nitella flexilis Ag. lose their power to respond to ordinary electrical stimulation after 2 or 3 days in distilled water. It returns after a day or so when they are replaced in their normal environment, in a suitable nutrient solution, or in a dilute solution of CaCl2.
Here anesthesia seems to be produced by removing something from the cell and this raises the question whether other cases of anesthesia may be explained in the same way.
The antagonistic action of calcium, in some cases at least, appears to depend on its power to prevent substances from leaching out of the cell.
THE CRYOSCOPIC METHOD FOR THE DETERMINATION OF "BOUND WATER"
Authors: Gortner Ross Aiken , Gortner Willis Alway 
Published: May 2004

1. The criticisms by Grollman (7) of the cryoscopic method for the determination of bound water as proposed by Newton and Gortner (1) have been considered, and it is pointed out that even admitting the correctness of his contentions does not negative the conclusion that bound water values as determined by the cryoscopic method parallel in a remarkable manner the physiological responses of plants to environmental conditions.
2. A new method of calculating the true freezing point of a solution is proposed.
3. Gum acacia in aqueous sucrose solutions shows positive amounts of bound water to the extent of 0.6 to 0.7 gm. of bound water per gram of gum.
4. Gum acacia in aqueous solutions of KCl and KBr shows slightly negative amounts of bound water, indicating a preferential adsorption of the solute rather than the solvent.
A NOTE ON THE RESPIRATION OF ARBACIA EGGS
Authors: Gerard R. W. , Rubinstein B. B. 
Published: May 2004

Methods used in preparing Arbacia eggs for respiration studies, in carrying through the manometric determinations, and in estimating egg quantities have been reexamined.
Discrepancies in previous results are almost entirely due to a steady error in measuring egg volume by centrifuging. Volumes so obtained averaged 80 per cent too high.
The respiration of unfertilized eggs of Arbacia punctulata at 21°C. is 0.9 c.mm. O2 per hour per 10 c.mm. of eggs.
THE EQUILIBRIUM BETWEEN ACTIVE NATIVE TRYPSIN AND INACTIVE DENATURED TRYPSIN
Authors: Anson M. L. , Mirsky A. E. 
Published: May 2004

There is a mobile equilibrium between the native and denatured forms of trypsin which depends on the concentrations of acid, alkali, and alcohol and on the temperature.
The heat of denaturation in 0.01 N hydrochloric acid calculated from the effect of temperature on the equilibrium constant is –67,600 calories per mole.
THE VISUAL ACUITY AND INTENSITY DISCRIMINATION OF DROSOPHILA
Authors: Hecht Selig , Wald George 
Published: May 2004

Drosophila possesses an inherited reflex response to a moving visual pattern which can be used to measure its capacity for intensity discrimination and its visual acuity at different illuminations. It is found that these two properties of vision run approximately parallel courses as functions of the prevailing intensity.
Visual acuity varies with the logarithm of the intensity in much the same sigmoid way as in man, the bee, and the fiddler crab. The resolving power is very poor at low illuminations and increases at high illuminations. The maximum visual acuity is 0.0018, which is 1/1000 of the maximum of the human eye and 1/10 that of the bee.
The intensity discrimination of Drosophila is also extremely poor, even at its best. At low illuminations for two intensities to be recognized as different, the higher must be nearly 100 times the lower. This ratio decreases as the intensity increases, and reaches a minimum of 2.5 which is maintained at the highest intensities. The minimum value of ΔI/I for Drosophila is 1.5, which is to be compared with 0.25 for the bee and 0.006 for man.
An explanation of the variation of visual acuity with illumination is given in terms of the variation in number of elements functional in the retinal mosaic at different intensities, this being dependent on the general statistical distribution of thresholds in the ommatidial population. Visual acuity is thus determined by the integral form of this distribution and corresponds to the total number of elements functional. The idea that intensity discrimination is determined by the differential form of this distribution—that is, that it depends on the rate of entrance of functional elements with intensity—is shown to be untenable in the light of the correspondence of the two visual functions. It is suggested that, like visual acuity, intensity discrimination may also have to be considered as a function of the total number of elements active at a given intensity.
THE POTASSIUM EQUILIBRIUM IN MUSCLE
Authors: Fenn Wallace O. , Cobb Doris M. 
Published: May 2004

1. Analyses were made of the K and HCO3 content, the irritability, and weight change of isolated frog sartorius muscles after immersion for 5 hours in Ringer's solutions modified as to pH and potassium content.
2. At each pH a concentration of potassium in the solution was found which was in diffusion equilibrium with the potassium in the muscle. In greater concentrations potassium moved into the muscle against the concentration gradient and vice versa.
3. The greater the alkalinity of the solution the smaller the concentration of the potassium at equilibrium so that the product of the concentrations of OH and K in the solution at equilibrium tends to remain approximately constant.
4. The pH inside the muscle is approximately equal to that outside when first dissected but it tends to change during immersion so as to follow the changes in the pH of the solution. This finding is in direct conflict with the theory according to which the high potassium concentration inside should be accompanied by an equally high hydrogen ion concentration in relation to that outside.
5. The diffusion of potassium into the muscle makes its contents more alkaline but the increase in alkalinity is not always, nor usually, equivalent to the amount of potassium which has diffused and conversely, the pH inside can change in either direction according to the pH outside without there being any diffusion of potassium. Hence potassium is not the only penetrating ion.
6. The irritability of the muscles is at a maximum in concentrations of potassium which are greater than that in normal Ringer's solution, or about 20 mg. per cent potassium. This optimum does not seem to be a function of pH and is therefore not dependent upon the direction of movement of the potassium but probably on the ratio of potassium outside to that inside.
7. Swelling of the muscles occurs in solutions which injure the muscle so as to permit both cations and anions to enter without permitting the organic protein anions to escape. Anion impermeability is necessary to prevent this same osmotic swelling under normal conditions.
8. An increase in the CO2 tension in muscle and solution causes a greater increase in acidity in the solution than in the muscle and leads to a loss of potassium. One expects therefore a potassium shift from tissues to blood comparable to the chlorine shift from plasma to corpuscles.
THE DIFFUSION OF CARBON DIOXIDE IN TISSUES
Authors: Wright Charles I. 
Published: May 2004

1. Two methods are given for measuring the rate of diffusion of CO2 in tissue membranes. Methods are also given for the determination of tissue thickness and the absorption coefficient for CO2 in tissues.
2. The values obtained for the permeability constant (P x 104) at 22°C. for CO2 in the following tissues are:—frog skin, 3.05; connective tissue (dog), 2.65; smooth muscle (cat), 5.00; frog muscle, 5.29; striated muscle (dog), 4.70. P is expressed as cc. per cm.2 per minute under a pressure gradient of one atmosphere per cm.
3. Evidence is presented to show that in a "steady state" bicarbonate contributes a negligible amount to the diffusion of CO2.
4. The absorption coefficient for CO2 in frog skin is 0.73 cc. per cc. and for frog muscle 0.78 cc. per cc.
5. In all of the tissues studied the diffusion of CO2 is slower than in water. The diffusion coefficients (K x 104 in cm.2/minute) at 22°C. for tissues as compared with water are:—water (16°C.), 9.5 (Hüfner, 1897); frog skin, 4.1; connective tissue, 3.7; frog muscle, 6.8; striated muscle (dog), 6.0; smooth muscle (cat), 6.4.
6. The time course of saturation of a tissue with CO2 is altered in the presence of available base. Non-acidified tissues saturate more slowly than acidified tissues and the rate of saturation is dependent on the CO2 tension.