bluuebunny/crossref_metadata_2025 huggingface dataset:
MEMBRANE POTENTIALS AND CATAPHORETIC POTENTIALS OF PROTEINS
Authors: Loeb Jacques
Published: May 2004

1. It has been shown in preceding publications that the membrane potentials of protein solutions or gels are determined by differences in the concentration of a common ion (e.g. hydrogen ion) inside a protein solution or protein gel and an outside aqueous solution free from protein, and that the membrane potentials can be calculated with a good degree of accuracy from Donnan's equation for membrane equilibria.

2. On the basis of the theory of electrical double layers developed by Helmholtz, we are forced to assume that the cataphoretic potentials of protein particles are determined by a difference in the concentration of the two oppositely charged ions of the same electrolyte in the two strata of an electrical double layer surrounding the protein particle but situated entirely in the aqueous solution.

3. The membrane potentials of proteins agree with the cataphoretic potentials in that the sign of charge of the protein is negative on the alkaline side and positive on the acid side of the isoelectric point of the protein in both membrane potentials and cataphoretic potentials. The two types of potential of proteins disagree, especially in regard to the action of salts with trivalent and tetravalent ions on the sign of charge of the protein. While low concentrations of these salts bring about a reversal of the sign of the cataphoretic potentials of protein particles (at least in the neighborhood of the isoelectric point), the same salts can bring the membrane potentials of proteins only to zero, but call bring about no or practically no reversal of the sign of charge of the protein. Where salts seem to bring about a reversal in the membrane potential of protein solutions, the reversal is probably in reality always due to a change in the pH.

4. We may state, as a result of our experiments, that the cataphoretic migration and the cataphoretic P.D. of protein particles or of suspended particles coated with a protein are the result of two groups of forces; namely, first, forces inherent in the protein particles (these forces being linked with the membrane equilibrium between protein particles and the outside aqueous solution); and second, forces inherent entirely in the aqueous solution surrounding the protein particles.

The forces inherent in the protein particles and linked with the membrane equilibrium prevail to such an extent over the forces inherent in the water, that the sense of the cataphoretic migration of protein particles is determined by the forces resulting from the membrane equilibrium.
STUDIES IN THE PHYSICAL CHEMISTRY OF THE PROTEINS
Authors: Cohn Edwin J. , Hendry Jessie L.
Published: May 2004

1. The solubility in water of purified, uncombined casein has previously been reported to be 0.11 gm. in 1 liter at 25°C. This solubility represents the sum of the concentrations of the casein molecule and of the soluble ions into which it dissociates.

2. The solubility of casein has now been studied in systems containing the protein and varying amounts of sodium hydroxide. It was found that casein forms a well defined soluble disodium compound, and that solubility was completely determined by (a) the solubility of the casein molecule, and (b) the concentration of the disodium casein compound.

3. In our experiments each mol of sodium hydroxide combined with approximately 2,100 gm. of casein.

4. The equivalent combining weight of casein for this base is just half the minimal molecular weight as calculated from the sulfur and phosphorus content, and one-sixth the minimal molecular weight calculated from the tryptophane content of casein.

5. From the study of systems containing the protein and very small amounts of sodium hydroxide it was possible to determine the solubility of the casein molecule, and also the degree to which it dissociated as a divalent acid and combined with base.

6. Solubility in such systems increased in direct proportion to the amount of sodium hydroxide they contained.

7. The concentration of the soluble casein compound varied inversely as the square of the hydrogen ion concentration, directly as the solubility of the casein molecule, Su, and as the constants Ka1 and Ka2 defining its acid dissociation.

8. The product of the solubility of the casein molecule and its acid dissociation constants yields the solubility product constant, Su·Ka1·Ka2 = 2.2 x 10–12 gm. casein per liter at 25°C.

9. The solubility of the casein molecule has been estimated from this constant, and also from the relation between the solubility of the casein and the sodium hydroxide concentration, to be approximately 0.09 gm. per liter at 25°C.

10. The product of the acid dissociation constants, Ka1 and Ka2, must therefore be 24 x 10–12N.

11. It is believed that these constants completely characterize the solubility of casein in systems containing the protein and small amounts of sodium hydroxide.
SENSORY ADAPTATION AND THE STATIONARY STATE
Authors: Hecht Selig
Published: May 2004

1. Experiments are described which measure the sensitivity of animals exposed to continued illumination to which they have become adapted. It is shown that the amount of outside light energy necessary to stimulate an adapted animal increases with the intensity of the adapting illumination.

2. The data are analyzed quantitatively in terms of the reversible reaction S ⇌ P + A shown previously to account for the photic sensitivity of these animals. This analysis demonstrates that, though the amount of incident energy necessary for a minimal response varies with the adapting intensity, the actual amount of photochemical decomposition required to set off the sensory mechanism is a constant quantity.

3. The ability of these animals to come into sensory equilibrium with any sustained illumination is accounted for quantitatively by the presence of a stationary state in the reversible photochemical reaction S ⇌ P + A during which the concentrations of the three components are constant.

4. It is shown that the concentrations of these substances at the stationary state are automatically controlled by the outside intensity. Therefore, given the sensory mechanism as a basis, the adaptation of the animals to light and the consequent changes in sensitivity, are determined entirely by the light to which the animals are exposed.

5. Because of the properties of the stationary state, and of the constancy of photochemical decomposition for a minimal effect, it is suggested that the sensory system is not only the traditional receptor system, but is also a protecting layer which stabilizes and buffers the relation between the nervous system and the environment.
THE PHOTOCHEMICAL BASIS OF ANIMAL HELIOTROPISM
Authors: Northrop John H. , Loeb Jacques
Published: May 2004

1. Experiments on the heliotropic orientation of Limulus were made which confirmed Loeb's photochemical theory of animal heliotropism proposed first in 1888 and 1889 in experiments on insects, and later in experiments on other forms of animals.

2. It is shown that these animals are oriented by light in such a way that the product

I x t x cos α

is the same for the symmetrical photosensitive elements of the eyes or the skin, where I is the intensity of the light, t the duration of illumination, and α the angle of incidence of the light at the surface element of the photosensitive organ.

3. When this equation holds, the products of decomposition by light must be the same in symmetrical elements of the eyes or skin, and the influence of these products of decomposition on the tension of symmetrical muscles of the locomotor organs of the animal must be the same. As a consequence the animal must move in the path of light, either to or from the source of light.
THE STABILITY OF BACTERIAL SUSPENSIONS
Authors: Northrop John H.
Published: May 2004

1. The concentrations of various salts required to agglutinate different concentrations for a suspension of typhoid bacilli sensitized with immune serum have been determined.

2. The electrolytes may be divided into two classes; (1) those with which the concentration required to agglutinate is independent of the concentration of the suspension; and (2) those with which the agglutinating concentration increases in proportion to the concentration of the suspension.

3. The salts comprised under (1) do not reverse the sign of the charge of the suspension.

4. The salts of Class (2) (with the exception of ZnSO4) do reverse the sign of the charge.
VALENCY RULE AND ALLEGED HOFMEISTER SERIES IN THE COLLOIDAL BEHAVIOR OF PROTEINS
Authors: Loeb Jacques , Kunitz M.
Published: May 2004

1. The action of a number of acids on four properties of gelatin (membrane potentials, osmotic pressure, swelling, and viscosity) was studied. The acids used can be divided into three groups; first, monobasic acids (HCl, HBr, HI, HNO3, acetic, propionic, and lactic acids); second, strong dibasic acids (H2SO4 and sulfosalicylic acid) which dissociate as dibasic acids in the range of pH between 4.7 and 2.5; and third, weak dibasic and tribasic acids (succinic, tartaric, citric) which dissociate as monobasic acids at pH 3.0 or below and dissociate increasingly as dibasic acids, according to their strength, with pH increasing above 3.0.

2. If the influence of these acids on the four above mentioned properties of gelatin is plotted as ordinates over the pH of the gelatin solution or gelatin gel as abscissæ, it is found that all the acids have the same effect where the anion is monovalent; this is true for the seven monobasic acids at all pH and for the weak dibasic and tribasic acids at pH below 3.0. The two strong dibasic acids (the anion of which is divalent in the whole range of pH of these experiments) have a much smaller effect than the acids with monovalent anion. The weak dibasic and tribasic acids act, at pH above 3.0, like acids the anion of which is chiefly monovalent but which contain also divalent anions increasing with pH and with the strength of the acid.

3. These experiments prove that only the valency but not the other properties of the anion of an acid influences the four properties of gelatin mentioned, thus absolutely contradicting the Hofmeister anion series in this case which were due to the failure of the earlier experimenters to measure properly the pH of their protein solutions or gels and to compare the effects of acids at the same pH of the protein solution or protein gel after equilibrium was established.

4. It is shown that the validity of the valency rule and the non-validity of the Hofmeister anion series for the four properties of proteins mentioned are consequences of the fact that the influence of acids on the membrane potentials, osmotic pressure, swelling, and viscosity of gelatin is due to the Donnan equilibrium between protein solutions or gels and the surrounding aqueous solution. This equilibrium depends only on the valency but not on any other property of the anion of an acid.

5. That the valency rule is determined by the Donnan equilibrium is strikingly illustrated by the ratio of the membrane potentials for divalent and monovalent anions of acids. Loeb has shown that the Donnan equilibrium demands that this ratio should be 0.66 and the actual measurements agree with this postulate of the theory within the limits of accuracy of the measurements.

6. The valency rule can be expected to hold for only such properties of proteins as depend upon the Donnan equilibrium. Properties of proteins not depending on the Donnan equilibrium may be affected not only by the valency but also by the chemical nature of the anion of an acid.
EXOSMOSIS IN RELATION TO INJURY AND PERMEABILITY
Authors: Osterhout W. J. V.
Published: May 2004

The time curve expressing the increase in the permeability of Nitella during the progress of death is practically the same whether derived from measurements of exosmosis or of electrical resistance.
THE PENETRATION OF DYES AS INFLUENCED BY HYDROGEN ION CONCENTRATION
Authors: Irwin Marian
Published: May 2004

When cells of Nitella are placed in buffer solutions at pH 9, there is a very slow and gradual increase in the pH of the sap from pH 5.6 to 6.4 (when death of the cells takes place). If the living cells are placed in 0.002 per cent dye solutions of brilliant cresyl blue at different pH values (from pH 6.6 to pH 9), it is found that the rate of penetration of the dye, and the final equilibrium attained, increases with increase in pH value, which can be attributed to an increase in the active protein (or other amphoteric electrolyte) in the cell which can combine with the dye.
COMPARATIVE STUDIES ON RESPIRATION
Authors: Ray George B.
Published: May 2004

A mathematical analysis of the effects of chloroform on the production of carbon dioxide by living Ulva, killed Ulva, and unsaturated organic acids indicates that the same process is taking place in all three cases. On the basis of this interpretation it is reasonable to conclude that the action of chloroform on the oxidative mechanism of the cell is chemical in nature and that it acts either by catalysis or by the formation of a loose compound with some portion of the system.
THE EFFECT OF GESTATION ON THE RATE OF DECLINE OF MILK SECRETION WITH THE ADVANCE OF THE PERIOD OF LACTATION
Authors: Brody Samuel , Ragsdale Arthur C. , Turner Charles W.
Published: May 2004

1. Data are presented showing that the course of decline of milk secretion with the advance of the period of lactation in farrow cows follows the course of decline of a monomolecular chemical reaction, that is each month's milk production is a constant percentage of the production of the preceding month (94.77 per cent in the case of the cow under consideration), from which it is inferred that milk secretion is limited by a chemical reaction initiated at parturition, and declining with the decrease of the concentration of the limiting substance as it is transformed into milk.

2. Data are presented showing that the decline in milk secretion due to pregnancy is related to the increase in weight of gestating animals, from which it is inferred that growth of the fetus is in part, at least, responsible for the decline in the milk flow due to the demand of the fetus for nutrients to support its life processes.
THE RELATION BETWEEN THE ELECTRICAL CONDUCTIVITY OF THE EXTERNAL MEDIUM AND THE RATE OF CELL DIVISION IN SEA URCHIN EGGS
Authors: Lillie R. S. , Cattell Ware
Published: May 2004

Dilution of sea water with isotonic sugar solution leaves the rate of cleavage of Arbacia eggs almost unchanged until the proportion of sea water is decreased to 20 or 25 volumes per cent. From this point cleavage becomes progressively slower with further dilution. Many eggs fail to cleave at dilutions of 5 to 6 volumes per cent. No cleavage occurs in 2 volumes per cent sea water or in pure sugar solution. Eggs returned from these media to sea water resume cleavage and development.

There is thus no relation between the rate of cleavage and the electrical conductivity of the medium, except possibly within the range of dilutions from 20 to 5 volumes per cent sea water. In this range cleavage rate decreases as conductivity decreases, but the relation is not a linear one.
THE EFFECT OF RADIOACTIVE RADIATIONS AND X-RAYS ON ENZYMES
Authors: Hussey Raymond G. , Thompson William R.
Published: May 2004

Pepsin in solution is inactivated by the radiations (beta and gamma) from radium emanation. This chemical effect has been studied quantitatively.

The principles involved in this radiochemical reaction are apparently the same as those found in the case of trypsin previously reported; namely, the change in the logarithm of the concentration of active enzyme varies directly with the variable, W.
THE RATE OF GROWTH OF THE DAIRY COW
Authors: Brody Samuel , Ragsdale Arthur C. , Turner Charles W.
Published: May 2004

Data are presented on the effect of age on milk secretion in the dairy cow. From the age when milk secretion usually begins (2 years) to the age when maximum body weight is reached (about 8 years) increase of milk secretion and increase of body weight with age follow the same exponential course, which is the course of a monomolecular reaction of chemistry. After this age, unlike body weight which remains practically constant, milk secretion declines exponentially, that is, the course of decline follows the course of decline of a monomolecular reaction. The whole course of milk secretion with age was therefore found to follow approximately the course of two simultaneous, consecutive, monomolecular reactions. This is taken to mean that growth and senescence go on simultaneously from the beginning to the end of life, and that each follows an exponential law with age; and therefore perhaps that the course of the two processes are limited by two consecutive chemical reactions.
THE RATE OF SENESCENCE OF THE DOMESTIC FOWL AS MEASURED BY THE DECLINE IN EGG PRODUCTION WITH AGE
Authors: Brody Samuel , Henderson Earl W. , Kempster H. L.
Published: May 2004

Data are presented showing that the course of decline of egg production with age in the domestic fowl from the time laying begins up to and including 8 years follows an exponential law, that is, each year's egg production is a constant percentage of the preceding year's production (88 per cent in the group of fowl studied). Since the exponential law is the same as the law of monomolecular change in chemistry, and since the course of egg production with age may be taken as an index of the course of senescence of organs, or tissues limiting egg production, it is suggested that this exponential law of egg production substantiates the idea that senescence is a physicochemical process the course of which is limited by a chemical reaction. It is shown that the exhaustion of the oocytes is not likely to be the factor limiting the course of egg production.
FURTHER EXPERIMENTS ON THE ABSORPTION OF IONS BY PLANTS, INCLUDING OBSERVATIONS ON THE EFFECT OF LIGHT
Authors: Hoagland D. R. , Davis A. R.
Published: May 2004

1. The conditions of illumination were found to exert a very significant influence on absorption of ions from dilute solution by Nitella. These conditions were also found to influence the penetration of Br and NO3 into the cell sap.

2. It is concluded that absorption of ions by plants from dilute solutions involves energy exchanges, with light as the ultimate source of the energy. It is suggested that the absorption is intimately related to growth and metabolism.

3. One ion may affect the removal from solution or penetration into the cell sap of another ion present in the same solution, even in solutions of extremely low concentration. It is probable that all three types of relations may exist—anion to anion, cation to cation, and anion to cation.

4. The sulfate and phosphate ions exerted far less influence on the absorption of nitrate than did chlorine and bromine ions. It is suggested as a possibility that sulfate does not penetrate readily to those surfaces at which chlorine, bromine, nitrate, and other ions may become effective.
THE EFFECT OF RADIOACTIVE RADIATIONS AND X-RAYS ON ENZYMES
Authors: Hussey Raymond G. , Thompson William R.
Published: May 2004

In this communication we have introduced a unit to express activity or power of a given preparation of radium emanation. We have named this unit the curie-power and defined it as the activity of 1 curie of radium emanation and its radioactive products in equilibrium with it. We suggest the introduction of this unit in order that we may make a more comprehensive statement of our experimental observation.

In the radiochemical reaction effected by the radiations (beta and gamma) from radium emanation in which enzymes are inactivated the chemical change in a given system is a function of the product of two variables; namely, the average activity of the radium emanation, Pa, expressed in terms of the unit millicurie-power, and time, t, expressed in hours. This product has the dimensions of energy and is identical with W which is measured in terms of the energy unit, millicurie-power hours.
THE FUNCTION OF THE BRAIN IN LOCOMOTION OF THE POLYCLAD WORM, YUNGIA AURANTIACA
Authors: Moore A. R.
Published: May 2004

Coordinated swimming movements in Yungia are not dependent upon the presence of the brain. The neuromuscular mechanism necessary for spontaneous movement and swimming is complete in the body of the animal apart from the brain. Normally this mechanism is set in motion by sensory stimulation arriving by way of the brain. The latter is a region of low threshold and acts as an amplifier by sending the impulses into a great number of channels. When the head is cut off these connections with the sensorium are broken, consequently peripheral stimulation does not have its usual effect. If, however, the motor nerves are stimulated directly as by mechanical stimulation of the median anterior region, then swimming movements result. Also if the threshold of the entire nervous mechanism is lowered by phenol or by an increase in the ion ratios

See PDF for Equation

and

See PDF for Equation

then again peripheral stimulation throws the neuromuscular mechanism into activity and swimming movements result.
THE COMBINATION OF DEAMINIZED GELATIN WITH HYDROCHLORIC ACID
Authors: Hitchcock David I.
Published: May 2004

1. The analysis of isoelectric gelatin by the Van Slyke method indicates 0.00040 equivalents of amino N per gm. gelatin.

2. If deaminized gelatin is prepared without heating, the product contains less nitrogen than the original gelatin by an amount equal to 0.00040 equivalents N per gm. protein.

3. Deaminized gelatin, prepared either with or without heating, contains no amino nitrogen detectable with certainty by either the Van Slyke or the formol titration method.

4. The isoelectric point of deaminized gelatin prepared without heating is at pH 4.0.

5. The maximum combining capacity of this protein for HCl is 0.00044 equivalents per gm.

6. The maximum combining capacity of gelatin for HCl should be corrected to 0.00089 equivalents per gm.

7. The difference between these maximum combining capacities, 0.00045, is nearly equivalent to the loss in amino or total nitrogen occurring in the deaminizing reaction.

8. This equivalence constitutes a new indication that the combination of protein with acid is chemical combination.
INFLUENCE OF LIGHT OF VERY LOW INTENSITY ON PHOTOTROPIC REACTIONS OF ANIMALS
Authors: Hartline H. Keffer
Published: May 2004

1. The negative phototropism of certain land isopods was investigated over a large range of intensities, especially low ones. The responses were determined quantitatively by measuring the angle through which an animal turned away from a line perpendicular to the rays of light.

2. In the absence of light the undirected movements set up by obscure stimuli were such as to compensate each other statistically, the average path being a movement in the direction in which the animal was headed.

3. Over a large range of intensities (0.0026 m.c. up) the average turning is maximal, about 55° (Oniscus). This maximal response is due to an anatomical peculiarity, in that the carapace cuts off the light on the eye after the animal has turned 50–60°. This peculiarity probably accounts for specific differences among land isopods. Any light, therefore, which is strong enough to turn an animal through this maximal angle in a radial distance of 10 cm. will give results whose mean will be maximal.

4. Below 0.0026 m.c. the amount of angular deflection becomes less and less, in proportion to the logarithm of the intensity, until at 0.00003 m.c. the movements are the same as in darkness.

5. This proportionality between amount of turning and the logarithm of the intensity indicates the photochemical nature of phototropism on the basis of Hecht's work with Mya. As a result, Loeb's theory of phototropism may then be stated in the mathematical form

See PDF for Equation

in which I1 and I2 are the two intensities, E1 and E2, their respective effects, and R, the muscular action set up by the difference in photochemical effect on the two sides.
EXPERIMENTS ON TOLERATION OF TEMPERATURE BY DROSOPHILA
Authors: Plough Harold H. , Strauss Maurice B.
Published: May 2004

1. Most wild stocks of Drosophila melanogaster can be bred indefinitely on banana agar at a temperature of 31°C. There is no relation between the geographical origin of these stocks and their ability to tolerate this temperature.

2. A single wild stock has been found which will breed for only one generation at temperatures above 29°C. The offspring hatched at 31°C. will breed normally at 24°C. This difference from other wild stocks is apparently genetic, but its genetic basis has not yet been worked out.

3. The mutant stocks of D. melanogaster tested by us will breed for only one generation at 31°C. and their offspring at this temperature are also fertile at 24°C. This condition is apparently a physiological effect of the presence of any of the mutant genes in a homozygous condition.

4. Similar tests indicate that wild stocks of D. virilis and Chymomyza procnemis will breed at 31°C., while D. simulans, D. immigrans, and D. funebris will not. The last two species are northern forms not commonly found in the tropics.

5. Both male and female flies from mutant stocks hatched at 31°C. produce offspring at this temperature if mated to flies hatched at 24°C. Their germ cells are therefore capable of development, and the cause of their failure to develop at 31°C. when inbred must lie either in the failure of the germ cells to reach each other or in the fertilization process itself.
CONDUCTIVITY TITRATION OF GELATIN SOLUTIONS WITH ACIDS
Authors: Hitchcock David I.
Published: May 2004

Titrations have been made, by the conductivity method, of gelatin solutions with hydrochloric and sulphuric acids. The results indicate an end-point at about 8.6 cc. of N/10 acid per gm. of gelatin, or a combining weight of about 1,160. These results are in fair agreement with those previously obtained by the hydrogen electrode method. Better agreement between the two methods was found in the case of deaminized gelatin. The data are in accord with a purely chemical conception of the combination between protein and acid.
THEORY OF REGENERATION BASED ON MASS ACTION. II
Authors: Loeb Jacques
Published: May 2004

1. Quantitative proof is furnished that all the material available for shoot and root formation in an isolated leaf of Bryophyllum calycinum flows to those notches where through the influence of gravity or by a more abundant supply of water growth is accelerated. As soon as the acceleration of growth in these notches commences, the growth of shoots and roots in the other notches which may already have started ceases.

2. It had been shown in a preceding paper that the regeneration of an isolated piece of stem may be and frequently is in the beginning not markedly polar, but that after some time the growth of all the roots except those at the base and of all the shoots except those at the apex is suppressed. This analogy with the behavior of regeneration in a leaf in which the growth in one set of notches is accelerated, suggests that in an isolated stem a more rapid growth is favored at the extreme ends (probably by a block of the sap flow at the extreme ends) and that when this happens the total flow of ascending sap goes to the most apical buds and the total flow of the descending sap goes to the most basal roots. As soon as this occurs, the growth of the other roots and shoots is suppressed.
THE KINETICS OF TRYPSIN DIGESTION
Authors: Northrop John H.
Published: May 2004

1. The rate of hydrolysis of a casein solution by trypsin is not affected by the addition of gelatin. The trypsin, therefore, is not combined with the gelatin unless there is a separate enzyme for casein and for gelatin.

2. The presence of casein protects the gelatin-splitting power of trypsin from heat inactivation, and the presence of gelatin protects the casein-splitting power from heat inactivation.

3. It does not seem possible to account for both the above results by the assumption of an intermediate compound between enzyme and substrate, since, in order to account for the first result, a different enzyme must be assumed for each protein, while, to account for the second result, it must be assumed that the same enzyme attacks both.
THE KINETICS OF SENESCENCE
Authors: Brody Samuel
Published: May 2004

The course of decline of vitality with age due to the process of senescence, when not complicated by the process of growth, follows a simple exponential law; that is the degree of vitality or of senescence (defining vitality as the reciprocal of senescence) at any moment is, regardless of age, a constant percentage of the degree of vitality or senescence of the preceding moment. This exponential law is the same as the law of monomolecular change in chemistry.

During the actively growing period of life the index of vitality rises, due to the process of growth and the course of vitality in the case when the growing period is included in the vitality curve, follows a rising and falling course. This rising and falling course may often be represented by an equation containing two exponential terms which is practically the equation used to represent the course of accumulation and disappearance of a substance as the result of two simultaneous consecutive monomolecular chemical reactions.
ISOELECTRIC POINTS FOR THE MYCELIUM OF FUNGI
Authors: Robbins William J.
Published: May 2004

1. Mycelium of Rhizopus nigricans when stained with certain acid and basic dyes and washed with buffer mixtures of 0.1 M phosphoric acid and sodium hydroxide responded much like an amphoteric colloid with an isoelectric point near pH 5.0.

2. When grown on potato dextrose agar the reaction of which was varied with phosphoric acid the extent of colony growth of Rhizopus nigricans plotted against the initial Sörensen value of the agar produced a double maximum curve with the minimum between the two maxima at initial pH 5.2.

3. When grown in potato dextrose broth the reaction of which was varied with phosphoric acid the dry matter produced by Rhizopus nigricans plotted against the Sörensen value of the broth produced a double maximum curve with the minimum between the two maxima at initial pH 5.2 or average pH 4.9.

4. Mycelium of Rhizopus nigricans placed in buffer mixtures of 0.01 M phosphoric acid and sodium hydroxide of pH 4.1 to 6.3, changed the reaction in most cases toward greater alkalinity.

5. Mycelium of Fusarium lycopersici stained with certain acid and basic dyes and washed with buffer mixtures of 0.1 M phosphoric acid and sodium hydroxide responded much like an amphoteric colloid with an isoelectric point near pH 5.5.
LUMIMESCENCE IN PELAGIA NOCTILUCA
Authors: Heymans (Ghent) C. , Moore (Rutgers) A. R.
Published: May 2004

1. Ca and K condition the irritability of Pelagia both in regard to rhythmical contractions and general luminescence. If either ion is omitted from the solution conduction of stimuli for pulsations and luminescence does not occur, although local responses still persist.

2. When Mg is omitted from the solution, Pelagia shows hyper-irritability with respect to rhythmical contraction and general luminescence. This is referable to the unantagonized action of K and Ca ions.

3. Exposure to the carbon arc suppresses general luminescence, the effect depending upon the quantity of light i.e. intensity x time of exposure.

4. The luminescent material secreted by Pelagia is inactive in sea water, but when put into salt solutions is activated by some of them. The efficiency of the salts, measured by brightness of light, is in the following order: MgSO4, K2SO4, Na3 citrate, KCl, BaCl2, SrCl2, CaCl2, and LiCl while NaCl and MgCl2 act as inhibitors.

5. Acidity inhibits the reaction, alkalinity promotes it. NH4OH in concentrations 0.27 N to 0.9 N causes luminescence for 10 minutes at 20°.

6. The average temperature coefficient for the reaction of the luminescent substance when activated by ammonia or MgSO4 is 2.18 for a temperature interval of 10°C.

7. The luminescence reaction cannot be the result of cytolysis, because (a) raising the temperature of sea water in which luminous material is immersed does not cause luminescence, although sufficient to produce cytolysis. (b) The salt solutions used in our experiments to cause luminescence, do not act cytolytically on cells in general.
THE EFFECT OF PHOSPHATES ON RESPIRATION
Authors: Lyon Charles J.
Published: May 2004

Phosphate accelerates both aerobic and anaerobic respiration. The acceleration almost disappears when the plant dies (in phosphate solution) but subsequently becomes greater than in life.
HYDROPHILIC AND HYDROPHOBIC COLLOIDS AND THE INFLUENCE OF ELECTROLYTES ON MEMBRANE POTENTIALS AND CATAPHORETIC POTENTIALS
Authors: Loeb Jacques
Published: May 2004

1. In order to be able to compare the effects of electrolytes on membrane potentials and cataphoretic potentials it seems necessary to distinguish between the charging and depressing effect of electrolytes on these potentials. Only low concentrations of acids and alkalies have a charging effect on the membrane potentials of proteins, while low concentrations of neutral salts have only a depressing effect; in the case of the cataphoretic potentials, low concentrations of salts have a charging effect as have also low concentrations of alkalies and in some cases low concentrations of acids. This difference finds its explanation in the difference of the origin of the two potentials and there can therefore be no common theory for the charging effect of electrolytes in the two cases.

2. There exists, however, an analogy in the depressing action of electrolytes on the two types of potentials inasmuch when the maximal P.D. is reached, all three kinds of electrolytes, acids, alkalies, and neutral salts, have a depressing effect on both types of potentials (taking into due consideration the effect of changes in the hydrogen ion concentration).

3. This depressing effect is adequately explained for the membrane potentials of protein solutions and protein gels on the basis of the Donnan equilibrium, and the question arises whether the same explanation may also hold for the cataphoretic potentials.

4. The active ion in the depressing action of electrolytes on membrane potentials as well as on cataphoretic potentials has the opposite sign of charge from that of the colloidal particle. It had been shown before that only the valency but not the chemical nature of the active ion determines the depressing effect in the case of membrane potentials and it is shown in this paper that the same is true for the cataphoretic potentials of particles of collodion, mastic, Acheson's graphite, and denatured egg albumin.

5. It is shown that the same valency rule holds also for the effect of acids on the cataphoretic potentials of collodion particles coated with gelatin, and that the ratio of the effect of dibasic to that of mono-basic acids is approximately 0.66, as Donnan's theory of membrane potentials would demand.

6. If we have a right to conclude from the validity of the valency rule for cataphoretic potentials that the depressing effect of electrolytes on the cataphoretic P.D. is determined by the Donnan equilibrium, we can understand the analogy between the depressing action of electrolytes on membrane potentials of hydrophilic colloids and on the cataphoretic potentials of hydrophobic colloids. We can also understand the analogy between the influence of electrolytes on the precipitation of hydrophobic colloids and on the depression of the values of all those properties of hydrophilic colloids which depend on the Donnan equilibrium, since the precipitation of hydrophobic colloids occurs when the cataphoretic P.D. is depressed below a critical value.
A TEST FOR DIFFUSIBLE IONS
Authors: Northrop John H.
Published: May 2004

1. The Donnan equilibrium furnishes a test for the ionic nature of any diffusible substance, since the ratio of the concentration of any ion on the two sides of a membrane must be equal to the ratio of the concentrations of any other ion of the same sign and valence, whereas a non-ionic substance would be equally distributed on both sides.

2. The distribution of trypsin inside and outside of gelatin particles has been compared to the distribution of hydrogen and chloride ions under the same conditions.

3. The ratio of the trypsin concentration in the gelatin to the concentration in the outside liquid is equal to the ratio of the hydrogen ion under the same conditions and to the reciprocal of the chloride ion ratio.

4. This result was obtained between pH 2.0 and 10.2. At pH 10.2 the trypsin is equally distributed and on the akaline side of 10.2 the ratio is directly equal to the chloride ratio.

5. Trypsin is therefore a positive monovalent ion in solutions of pH 10 to 2. It is probably isoelectric at 10.2 and a monovalent negative ion on the alkaline side of 10.2

6. Trypsin must also be a strong base since there is no evidence of any undissociated form on the acid side of pH 10.2.
INTENSITY DISCRIMINATION AND THE STATIONARY STATE
Authors: Hecht Selig
Published: May 2004

1. A method of experimentation is described which enables one to record objectively and quantitatively the discrimination by Mya between two intensities of illumination to which it is successively exposed. The indicator for this discrimination is a response at a given reaction time.

2. From the data so obtained it is found that the difference, ΔI, between the two intensities bears no constant relation to the initial intensity, I. Instead, the ratio

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varies in a consistent manner with I. As the latter increases, the ratio decreases to a certain point, after which it increases.

3. The data are analyzed in terms of the photochemical mechanism previously proposed for the sensitivity of Mya to light. It is shown that for the animal to discriminate by means of a given reaction between one intensity and another, the transition from one to the other must be accompanied by the decomposition of a constant amount of photosensitive substance in the sense organ.

4. A mathematical treatment of the behavior of the photochemical mechanism shows not only that the ratio

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cannot be constant as required by the Weber-Fechner law, but that it must vary in the way in which it does. The behavior of Mya under these conditions, therefore, supports the validity of the hypothetical physicochemical mechanism suggested for its sensitivity.
THE REACTION OF CERIANTHUS TO TWO SOURCES OF LIGHT
Authors: Moore Mary Mitchell
Published: May 2004

1. In case Cerianthus is acted upon by two lights of unequal intensities the relation between the angle turned and the ratio between the intensities of the two lights is mathematically expressed by the equation log10

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tan a, in which

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is the ratio of the two lights, a is the angle turned from the neutral position, and K = 0.615.

2. According to published data from experiments on other animals, the relation between the angle turned and the ratio between the intensities of the two lights may be expressed by the same equation.
LUMINESCENCE IN MNEMIOPSIS
Authors: Moore A. R.
Published: May 2004

1. In the dark adapted Mnemiopsis, mechanical stimulation causes luminescence along the eight rows of paddle plates. The tactile receptors for this reaction lie only in the paddle plate rows, and are connected only longitudinally along these rows.

2. The tactile receptors for ciliary and muscular movement are distributed generally over the surface and are connected by a nerve net.

3. Luminescence may occur at 3°C. provided the animal has been kept sufficiently long at that temperature. Ciliary action goes on at – 0.6°C.

4. Luminescent paper made by spreading the luminescent secretion of Mnemiopsis on filter paper, yields the following effects. The paper shows luminescence in solutions of K2SO4, KCl, MgSO4, SrCl2, CaCl2; no luminescence in NaCl, MgCl2. Changes in pH value of salt solutions between pH 6 and 8 do not affect the phenomenon. Illumination of the paper with strong light for longer time than necessary to suppress luminescence in the living animal has no effect on the subsequent luminescence of the paper. Hence in the animal, light affects luminescence through the photoreceptor system; the nervous system carries the impulse to the luminescent organs.

5. The power of luminescence of the animal is suppressed by sufficiently intense light, the relation between the intensity and the time requisite being expressed by the equation for the Bunsen-Roscoe photochemical law, namely, I · t = K.

6. It is suggested that the reaction scheme involved in luminescence is of the following form

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in which A is the luminescent substance in the resting, dark adapted animal, L is the light-giving decomposition product, and D is a product which does not yield light.

7. The luminescent substance receives double innervation and the character of the decomposition is determined by the type of nerve fiber stimulated.
THE KINETICS OF TRYPSIN DIGESTION
Authors: Northrop John H.
Published: May 2004

1. The kinetics of enzyme reactions diverge more or less from the simple mass action expression for a monomolecular reaction. There is good reason to believe that these discrepancies are due to other secondary reactions which also agree with the law of mass action. Attempts to incorporate all these reactions in one equation, however, are unsatisfactory owing to the complexity of the relations involved.

2. It is possible, however, to regulate conditions experimentally so that these secondary reactions are reduced to a minimum. This has been done in the case of trypsin digestion by working at a low temperature, which prevents inactivation of the trypsin, by using a large amount of trypsin, which prevents the inhibiting effect of the products from becoming noticeable, and by using the disappearance of the protein as the indicator which obviates the complicating effects of the consecutive reactions.

3. Under these conditions the hydrolysis, for any initial concentration of casein is accurately represented by the monomolecular formula,

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The effect of variations in the initial trypsin concentration are also correctly predicted.

4. If the initial casein concentration is varied, however, the value of the constant changes for each casein concentration, becoming less as the casein increases and eventually becoming nearly inversely proportional to the casein concentration. It is pointed out that this cannot be due to a compound between enzyme and casein, nor to the viscosity, but is probably owing to an equilibrium between the casein and water, in which the casein can be replaced by the first cleavage products. This is corroborated by the fact that if the casein is dissolved in a freshly prepared solution of digested casein, the anomalous effect of the substrate concentration disappears and the reaction is typically monomolecular in every respect. A solution of digested casein which has been in prolonged contact with trypsin does not have this effect.

5. It is pointed out that the various equations that have been proposed to account for the enzyme reactions on the basis of a compound between the enzyme and substrate could be applied equally well on the basis of a compound between water and the substrate which is attacked by the enzyme.
THE KINETICS OF TRYPSIN DIGESTION
Authors: Northrop John H.
Published: May 2004

1. A study has been made of the rate of hydrolysis of concentrated gelatin solutions at a high temperature and with a large amount of trypsin.

2. Under these conditions the substrate concentration may be considered constant and the only variable is the decrease in the amount of trypsin owing to inactivation.

3. The theory based on the mass law predicts that under these conditions (a) the rate at any time will be proportional to the concentration of trypsin at that time; (b) the reaction should approximate a monomolecular one if the total hydrolysis observed is taken as the amount of substrate available; (c) that the velocity constant calculated in this way should agree with the constant for the decomposition of the enzyme and that it should be independent of the concentration of enzyme instead of proportional to it as is usually the case; and (d) that the total amount of substrate decomposed should be proportional to the amount of trypsin added at the beginning instead of independent of it. These results have been obtained experimentally.
ON THE DIFFUSIBILITY OF THE CALCIUM OF BLOOD SERUM THROUGH COLLODION MEMBRANES
Authors: Loeb Robert F. ,   With the Assistance of S. Steinberger.
Published: May 2004

1. Serum calcium is completely diffusible through collodion membranes in 0.8 per cent NaCl at a pH of 7.4.

2. About 55 to 75 per cent of serum Ca is diffusible through collodion membranes in distilled water at a pH of 7.4.

3. Serum Ca is completely diffusible when dialyzed against HCl at a pH of 2.5.
THE ISOELECTRIC POINT OF GELATIN AT 40°C
Authors: Hitchcock David I.
Published: May 2004

Measurements have been made at 40°C. of the osmotic pressure and viscosity of 1 per cent gelatin solutions containing varying amounts of hydrochloric acid or sodium hydroxide. Each property was found to exhibit a decided minimum near pH 4.7. In the osmotic pressure experiments the pH of the inside solutions was greater than that of the outside solutions at pH values below 4.7, while it was less than that of the outside solutions at values above pH 4.7. These results indicate that gelatin at 40°C. retains its isoelectric point at about pH 4.7.
THEORY OF REGENERATION BASED ON MASS RELATION
Authors: Loeb Jacques
Published: May 2004

1. Small stems with one large leaf in the middle produce shoots and roots chiefly at the expense of material sent into the stem by the leaf. Since the sap of the leaf can cause the formation of roots and shoots in the same notch of the leaf, it is difficult to assume that the polar character of the regeneration in the stem is due to a chemical difference in the ascending and descending sap sent by the leaf into the stem.

2. When the ascending sap sent by a leaf into the stem is caused with the aid of gravity to reach those tissues of the stem from which roots are formed, an abundant root formation is produced by the ascending sap.

3. These two observations in connection with a fact already published in a preceding paper support the idea that the polar character of regeneration in a stem of Bryophyllum is not due to any of the chemical differences between the ascending and descending sap but to a difference in the nature of the tissues or anlagen which are primarily reached by the ascending and descending sap.
THE OXIDATION OF SODIUM LACTATE BY HYDROGEN PEROXIDE
Authors: Ray George B.
Published: May 2004

By means of a modification of the technique of the Osterhout apparatus it is possible to follow the production of CO2 from sodium lactate when acted upon by H2O2.

The results of this process indicate that the reaction is not a simple one but is of an autocatalytic type. This conclusion is borne out by the fact that the determinations of H2O2 during the reaction show an increased amount of peroxide during the earlier stages of the reaction. This is considered to be due to the formation of a peroxide by the oxidation of the acetaldehyde (formed by the interaction of H2O2 and sodium lactate) with the oxygen of the air. When the reaction is carried out in an atmosphere of nitrogen no increase is observed.

Further experiments in nitrogen tend to show that acetaldehyde is the end-product of the action of H2O2 alone.

The effect of FeCl3 upon the reaction depends upon the previous treatment of the iron salt. If the iron solution is added to the H2O2 before mixing with the lactate there is an increased amount of CO2. If, however, the iron is added to the lactate before the addition of the peroxide, the action tends to inhibit the production of CO2.

The reaction of H2O2 with sodium lactate is comparable to the action of killed yeast and methylene blue as determined by Palladin and his coworkers.