bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE COMBINATION OF SALTS AND PROTEINS. I
Authors: Northrop John H. , Kunitz M. 
Published: May 2004

1. It has been found that the ratios of the total concentrations of Ca, Mg, K, Zn, inside and outside of gelatin particles do not agree with the ratios calculated according to Donnan's theory from the hydrogen ion activity ratios.
2. E.M.F. measurements of Zn and Cl electrode potentials in such a system show, however, that the ion activity ratios are correct, so that the discrepancy must be due to a decrease in the ion concentration by the formation of complex ions with the protein.
3. This has been confirmed in the case of Zn by Zn potential measurements in ZnCl2 solutions containing gelatin. It has been found that in 10 per cent gelatin containing 0.01 M ZnCl2 about 60 per cent of the Zn++ is combined with the gelatin.
4. If the activity ratios are correctly expressed by Donnan's equation, then the amount of any ion combined with a protein can be determined without E.M.F. measurements by determining its distribution in a proper system. If the activity ratio of the hydrogen ion and the activity of the other ion in the aqueous solution are known, then the activity and hence the concentration of the ion in the protein solution can be calculated. The difference between this and the total molar concentration of the ion in the protein represents the amount combined with the protein.
5. It has been shown that in the case of Zn the values obtained in this way agree quite closely with those determined by direct E.M.F. measurements.
6. The combination with Zn is rapidly and completely reversible and hence is probably not a surface effect.
7. Since the protein combines more with Zn than with Cl, the addition of ZnCl2 to isoelectric gelatin should give rise to an unequal ion distribution and hence to an increase in swelling, osmotic pressure, and viscosity. This has been found to be the case.
OBSERVATIONS ON THE INJURIOUS EFFECTS OF HIGH TEMPERATURES ON FROG SKIN
Authors: Klopp John W. 
Published: May 2004

1. The P.D. between the two surfaces of the skin of the frog, when measured under standardized conditions, may be used as a means of studying the phenomena of injury, recovery, and death. Injurious conditions decrease the P.D.
2. According to the severity of the injury produced by temporary exposure to high temperatures, frog skin may show, as judged by this criterion (a) complete recovery, (b) partial recovery, or (c) a progressive change leading to death.
STUDIES IN THE PHYSICAL CHEMISTRY OF THE PROTEINS
Authors: Cohn Edwin J. , Berggren Ruth E. L. 
Published: May 2004

1. The methods of measuring the base-combining capacities of proteins have been considered, and the constants and corrections that are employed in their calculation have been critically examined.
2. The base-combining capacities of ten casein preparations have been determined. These differed from each other to a far greater extent than can be attributed to the experimental errors involved in their measurement and calculation. The variations were, moreover, systematic in manner, and can be explained as dependent upon the method employed in the preparation of the casein.
3. Casein that had never been exposed to greater alkalinities than those in which it exists in nature combined with approximately 0.0014 mols of sodium hydroxide per gm., while casein prepared nach Hammarsten, and casein that was saturated with base during its preparation, combined with approximately 0.0018 mols of sodium hydroxide per gm.
4. 1 mol of sodium hydroxide, therefore, combined with 735 gm. of casein that had not previously been exposed to alkaline reactions, or with 535 gm. of casein that had previously been saturated with base.
5. If the minimal molecular weight of casein, based upon its tryptophane content, is placed at 12,800, the native protein must, therefore, contain approximately eighteen acid groups, and in addition six acid groups that are released in alkaline solutions, and presumably represent internally bound groups. The total base-combining capacity therefore represents that of a substance with a molecular weight of 12,800 and containing twenty-four acid valences.
6. This base-combining capacity is no greater than can be accounted for on the basis of our knowledge of the structure and composition of casein. On the basis of a molecular weight of 12,800 casein contains at least 19 molecules of glutamic acid, 4 of aspartic, and 8 of hydroxyglutamic acid. If the amino acids in the protein molecule are bound to each other in polypeptide linkage, each of these thirty-one dicarboxylic acids should yield terminal groups. The ammonia in casein suggests that twelve of these groups are bound as amides. As many as nineteen carboxyl groups may, therefore, be free in the protein molecule.
7. Casein contains phosphorus. If this phosphorus represents phosphoric acid, and if we consider that all of the valences of this acid are either themselves free, or that they have liberated carboxyl groups by entering into the structure of the protein molecule, casein should contain nine additional acid groups.
8. Recent analytical results, therefore, indicate that casein contains at least nineteen, and possibly twenty-eight, free acid groups. The physicochemical measurements presented suggest that casein combines with base as though it contained twenty-four acid groups, of which six, or one-fourth, appear to be bound in the native protein. These experimental results are therefore in close agreement with the expectation on the basis of the classical theory of protein structure.
ON BIOLOGICAL OXIDATIONS AS FUNCTION OF TEMPERATURE
Authors: Crozier W. J. 
Published: May 2004

1. The critical thermal increments are calculated for respiratory processes (O2 consumption, CO2 production) in various plants and animals. They are characteristically found to be of two, possibly three, types: µ = 11,500, and 16,100 or 16,700. The first is commonly encountered above 15°, the second below that temperature, but these relations may be reversed. (The value of µ may be significantly changed in inanition.)
2. For reduction of methylene blue by bacteria, through removal of H from succinic acid, µ = 16,700. This process (Quastel and Whetham, 1924) at constant temperature is a function of the hydroxyl ion concentration. The suggestive identity is pointed out of the critical increment for this reduction phenomenon with that deduced for biological respirations in which a dehydrogenation mechanism is supposed to be of widespread occurrence, and in connection with which Fe very likely has a catalytic rôle. The action of OH' is believed to be revealed in the value µ = 11,500, frequently obtained in connection with respiration.
3. A somewhat lower µ (16,140) is associated with the oxidation of Fe'', and may be compared with (1) that of respiration in sea urchin eggs, for which (Warburg) iron is catalyst, and (2) that for some simple reactions in which Fe is known to serve as catalyst; it is not found for oxidative reactions in which Fe is not involved.
4. The bearing of these findings is discussed in relation to the theory of functional analysis of concurrent catalyzed reactions in protoplasm. It is shown that for a number of activities in which the effects of respiration may safely be assumed, the values of the critical increments are consistent with those determined for processes of respiration.
5. The further development of these views may lead to an extremely important method of identifying controlling reactions in undisturbed living matter.
STUDIES ON THE FORMATION AND IONIZATION OF THE COMPOUNDS OF CASEIN WITH ALKALI
Authors: Greenberg David M. , Schmidt Carl L. A. 
Published: May 2004

1. The deposition of casein on a platinum anode which takes place on the passage of a direct current through solutions of alkali caseinates was quantitatively studied, and it was found that: (a) the amount of casein which is deposited is directly proportional to the current, i.e. it obeys Faraday's law; (b) the amount of casein deposited is inversely proportional (within the limits studied) to the amount of alkali which is combined with the casein.
2. A method of determining the transport numbers of proteins insoluble at their isoelectric point has been developed.
3. A titration method for determining the amount of alkali in a casein solution is given.
4. Data from the results of transference experiments on sodium caseinate, potassium caseinate, cesium caseinate, and rubidium caseinate solutions are given. It is shown that the data are best explained on the assumption that in these solutions the carriers of the current are alkali metal cations and casein anions.
5. On the basis of our transference results an explanation is given of the results which were obtained by Robertson and by Haas in their migration experiments.
STUDIES ON THE FORMATION AND IONIZATION OF THE COMPOUNDS OF CASEIN WITH ALKALI
Authors: Greenberg David M. , Schmidt Carl L. A. 
Published: May 2004

1. The results of conductivity experiments with alkali caseinate solutions are given and a graphical method of extrapolation, which gives a straight line, is described. The results of the conductivity experiments are shown to be in accord with the results of the previous transference experiments.
2. The change of conductivity of the alkali caseinate solutions with temperature is shown to follow a straight line relationship.
3. The high value of the mobility which was obtained for the casein ion and the high temperature gradient are discussed in relation to McBain's theory of colloidal electrolytes.
STUDIES ON THE FORMATION AND IONIZATION OF THE COMPOUNDS OF CASEIN WITH ALKALI
Authors: Greenberg David M. , Schmidt Carl L. A. 
Published: May 2004

1. The phenomenon of protein racemization is discussed and certain deductions are made in connection with the hypothesis of Dakin to account for this phenomenon and Robertson's theory of the ionization of proteins.
2. Experimental data are given to show that the electrochemical behavior of racemic casein is not in accord with the deductions which have been drawn from the theory advanced by Robertson.
3. An analysis of the nitrogen groups of racemic casein is given and compared with a similar analysis of normal casein. From these analyses and from the electrochemical equivalent of racemic casein, it is concluded that except for the hydrolysis of amide groups, racemic casein is probably not a degradation product of casein.
4. Considerable evidence is presented against the view that the -COHN- groups take part in the reactions of the protein molecule with acids and with bases.
STUDIES ON BIOLUMINESCENCE
Authors: Harvey E. Newton 
Published: May 2004

1. Small dumps of the luminous cells of Mnemiopsis cannot readily be stimulated mechanically but will luminesce on treatment with saponin solution. Larger groups of luminous cells (such as are connected with two paddle plates) luminesce on mechanical stimulation. This suggests that mechanical stimulation to luminesce occurs chiefly through a nerve mechanism which has been broken up in the small dumps of luminous tissue.
2. The smallest bits of luminous tissue, even cells freed from the animal by agitation, that will pass through filter paper, lose their power to luminesce in daylight and regain it (at least partially) in the dark.
3. Luminescence of the whole animal and of individual cells is suppressed by near ultra-violet light (without visible light).
4. Inhibition in ultra-violet light is not due to stimulation (by the ultra-violet light) of the animal to luminesce, thereby using up the store of photogenic material.
5. Animals stimulated mechanically several times and placed in ultra-violet light show a luminescence along the meridians in the same positions as the luminescence that appears on stimulation. This luminescence in the ultra-violet or "tonic luminescence," is not obtained with light adapted ctenophores and is interpreted to be a fluorescence of the product of oxidation of the photogenic material.
6. Marked fluorescence of the luminous organ of the glowworm (Photuris) and of the luminous slime of Chatopterus may be observed in ultra-violet but no marked fluorescence of the luminous substances of Cypridina is apparent.
7. Evidence is accumulating to show a close relation between fluorescent and chemiluminescent substances in animals, similar to that described for unsaturated silicon compounds and the Grignard reagents.
CONDUCTIVITY AS A MEASURE OF THE PERMEABILITY OF SUSPENDED CELLS
Authors: Brooks S. C. 
Published: May 2004

The problem of determining by means of measurements of electrolytic conductance the permeability of living cells in suspension is considered in some detail and it is pointed out that several factors, usually neglected, have an important influence on the interpretation of such studies. These are:
1. The relative volume and the shape of cells, which are responsive to changes in osmotic pressure and constitution of the surrounding solution. The sources of error in various methods of determining the true volume of red blood cells in a suspension are explained. The hematocrit method appears to be the most reliable method in this case.
2. The proportion of living cells, which is especially to be regarded in the case of suspensions of bacteria. It is shown that this may be very high when appropriate cultural methods are used. The conductance of the dead cells must also be taken into account.
3. The progressive nature of the changes occurring during the course of an experiment. Approximate accuracy may be obtained by proper interpolation.
4. The conductivity of the protoplasm itself, which varies in response to variations is that of the surrounding fluid.
It is emphasized that cells, and in particular red blood cells, are not to be regarded as stable non-conducting particles, but rather as labile and as permeable to electrolytes. It is shown that the available data support this interpretation.
THYROXIN AS A DEPRESSANT OF THE DIVISION RATE OF PARAMECIUM
Authors: Torrey Harry Beal , Riddle Matthew C. , Brodie J. L. 
Published: May 2004

In concentrations of 1:104, 1:105, 1:106, in alkaline solution with a hydrogen ion concentration approximating that characteristic of normal human blood, thyroxin acts like total thyroid in accelerating certain metabolic processes in Paramecium, notably those connected with the phenomena of excretion.
Unlike total thyroid, thyroxin depresses the division rate of Paramecium, the degree of depression varying directly with its concentration.
This depression of the division rate is due to the action of the thyroxin directly on Paramecium, not to a modification of the food supply.
THE RELATION OF THE STABILITY OF PROTOPLASMIC FILMS IN NOCTILUCA TO THE DURATION AND INTENSITY OF AN APPLIED ELECTRIC POTENTIAL
Authors: Lund E. J. , Logan G. A. 
Published: May 2004

1. The experiments demonstrate that when a constant electric potential of sufficient intensity is applied to Noctiluca, the protoplasmic films which represent a part of the visible continuous phase of the cytoplasm and plasma membrane at the surface of the cell, become unstable and break down, thus releasing the acid contents of one of the internal discontinuous phases present in the cytoplasm of Noctiluca. This process which occurs first at anode then at the cathode side of the cell, appears to be a selective deemulsification or coalescence similar to that at the surface of an emulsion having a viscous continuous phase.
2. The experiments demonstrate that Nernst's equation
See PDF for Equation
which expresses approximately the relation of duration and intensity of a constant electric current to threshold stimulation of striated muscle, applies equally well to the process of anodal coalescence in Noctiluca.
3. Anodal and cathodal coalescence have different thresholds, due to the fact that the semipermeable plasma film at the surface of the cell is asymmetric with respect to the direction of the applied current. Attention is called to the possible relation between this phenomenon and the conditions occurring at the synapse between neurons.
4. The stability of the protoplasmic films in relation to the applied electric potential is greater in young cells than in old cells, or in other words the threshold intensity of the stimulus is higher for young than for old cells.
5. Attention is called to the occurrence in the same cell of different receptor-affector mechanisms having a corresponding difference in intensity threshold when an electric current is acting as a stimulus.
FACTORS AFFECTING TRANSMISSION AND RECOVERY IN THE PASSIVE IRON NERVE MODEL
Authors: Lillie Ralph S. 
Published: May 2004

1. The speed of transmission of the activation wave along passive iron wires enclosed in glass tubes containing dilute (70 per cent) nitric acid increases with the conductivity (sectional area) of the column of electrolyte but at a slower rate. The speed is closely proportional to the square root of the conductivity
See PDF for Equation.
The reasons for this relationship are discussed and an explanation is proposed.
2. The recovery of transmissivity after the passage of an activation wave is gradual and follows a characteristic course. After an interval of partial or decremental transmission (having a high temperature coefficient and lasting several minutes at 20°), the wire recovers its power of transmitting an activation wave for an indefinite distance. In such a recovered wire the speed of transmission is at first slow and increases by degrees up to a maximum, the increase following a curve apparently of the type vt = v0 (1 – e_kt). The approximate time required to attain this maximum (corresponding to complete recovery) at the different temperatures is 15 to 20 minutes at 20°, 30 to 45 minutes at 15°, ca. 60 minutes at 10°, and 90 minutes or more at 5°.
3. The character of the curve of recovery (the curve relating speed of transmission to interval since previous activation) agrees with the assumption that the increase in speed depends on a progressive chemical change in the molecules forming the passivating film, this change involving the transformation of (relatively) nonreactive into reactive molecules and following the course of a monomolecular reaction.
4. The temperature coefficient of the speed of transmission (between 5° and 20°) is low, of the order Q10 = 1.3 to 1.6. That of the rate of recovery, on the contrary, is high (Q10 = ca. 3). The parallel to the conditions in nerve and other transmitting protoplasmic systems is pointed out and discussed.
5. Passive wires enclosed in acid-containing continuous and interrupted glass tubes immersed in a large volume of acid exhibit characteristic phenomena of distance action; under appropriate conditions the velocity of transmission of the activating influence between different areas may thus be greatly increased. Characteristic instances are cited and some possible physiological parallels are pointed out.
NEUROID TRANSMISSION IN CILIATED EPITHELIUM
Authors: Wyman Jeffries 
Published: May 2004

Evidence from several sources indicates that there is present in certain types of ciliated tissue a primitive form of conduction regulating the rate of beat of the cilia. (Kraft, 1890; Engelmann, 1898). A similar type of conduction has been observed by Parker (1910) in the sponge Stylotella. In the foregoing experiments a study was made of such conduction in the ciliated tissue of the gills of the clam Unio. Observations were made on the effects of temperature changes on the rate of beat of cilia adjacent to areas not themselves directly influenced. The following results were obtained.
1. The transmission through the gill of the effects of warmth applied locally is apparent through increased rate of ciliary beat on adjacent gill tissue in all directions from the region of application. Effects are not observed laterally at a distance greater than 9 to 11 mm. from the nearest edge of the stimulated area. The narrowness of the gill makes it impossible to determine the vertical limits of the transmission.
2. Effects of low temperatures are not observable beyond the limits of the region of direct application.
These results differ from those of Kraft in tissue from the frog's pharynx, where conduction was shown to take place only down a row of beating cilia. On the other hand they agree with his results in indicating that the effects of warmth only are transmitted.
The phenomenon might be explained by the stimulating effect of the action current of the directly excited cilia on the neighboring relatively quiet cilia. A similar explanation has been offered by Lillie for waves of coordinated beating in the rows of swimming plates of ctenophores. Such an explanation, though in accord with the work on Unio, is inconsistent with certain of the observations of Kraft on the tissue from the frog's pharynx.
ON THE IMPORTANCE OF MAINTAINING CERTAIN DIFFERENCES BETWEEN CELL SAP AND EXTERNAL MEDIUM
Authors: Osterhout W. J. V. 
Published: May 2004

A striking difference exists between the internal and external solution in the case of Valonia macrophysa. If this difference is abolished by placing cells in their own sap most of them quickly die.
There is some ground for believing that the maintenance of differences between the sap and the external medium is of importance for vital processes.
The sap of Valonia macrophysa is not a balanced solution in the ordinary sense and the question may be raised whether in general the interior of the cell requires a balanced solution in order to maintain life: or it may be that we must distinguish between internal and external balanced solutions.
THE MECHANISM OF CHANGE IN RESISTANCE OF ERYTHROCYTES TO HYPOTONIC SALT SOLUTIONS
Authors: Brooks S. C. 
Published: May 2004

Ashby's work on the effects of KCl and NaCl on the resistance to hypotonic hemolysis of K•-rich and K•-poor erythrocytes has been repeated with great attention to purity of materials and refinement of technique. The results fail to agree with those of Ashby.
1. KCl produces greater loss in resistance to hypotonic hemolysis than does NaCl, irrespective of the species of the animal from which the cells are taken.
2. While cases of an increase in resistance have been encountered in my experiments, they are either very slight, or else the particular determination is subject to very great uncertainty. The great increases in resistance found by Ashby are not even approached in any of the present series of experiments.
3. Ashby's generalization that KCl and NaCl have opposite effects on red blood cells, and that the sense of these effects depends on whether the cell is K•-rich or K•-poor is not substantiated.
CONTRASTS IN THE CELL SAP OF VALONIAS AND THE PROBLEM OF FLOTATION
Authors: Osterhout W. J. V. , Dorcas M. J. 
Published: May 2004

The marine alga Valonia macrophysa contains in its cell sap K and Na in the proportion of 5.72 to 1. In a form regarded as closely related, Valonia ventricosa, growing in similar environment, the ratio of K to Na is as 0.0278 to 1. The former contains no Mg but in the latter it is present. There are other differences in the composition of the sap.
These differences bring about a remarkable contrast in behavior in that Valonia ventricosa floats in sea water while Valonia macrophysa sinks.
CARBON DIOXIDE FROM THE NERVE CORD OF THE LOBSTER
Authors: Parker G. H. 
Published: May 2004

1. The nerve cord of the lobster (Homarus americanus Milne-Edwards) is very delicate and can be used as a living preparation for only a few hours after its removal from the animal.
2. During the first hour or so after removal it discharges CO2 at a steadily decreasing rate beginning at about 0.20 mg. CO2 per gram of cord per minute and ending at about 0.07 mg.
3. This discharge exhibits a steady decrease in rate and is not divisible into a period of gush and a period of uniform outflow as with the lateral-line nerve of the dogfish. It terminates in a very few hours with the complete death of the cord.
4. Both handling and cutting the cord temporarily increase the rate of CO2 output.
5. The stimulated cord discharges CO2 at a rate about 26 per cent higher than that of the quiescent cord, an increase of about 1.6 times that of the increase observed in the lateral-line nerve of the dogfish under similar circumstances.