bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE CHROMOSOMES OF PARTHENOGENETIC FROGS AND TADPOLES
Authors: Parmenter Charles L. 
Published: May 2004

1. This paper presents cytological observations upon Dr. Loeb's parthenogenetic frog material, with considerations upon the mechanism by which the diploid number and both sexes may be produced.
2. Both sexes of adults and tadpoles are present.
3. The chromosome number is diploid and probably 26 in both sexes. Sex chromosomes cannot be distinguished.
4. The chromosome numbers observed by other authors in parthenogenetic frog material are haploid, diploid, and variable. Their significance is considered.
5. The mechanism producing the diploid number, based on European observations, appears to be a doubling of the haploid number at some time after the second polar body is given off.
6. Overripeness may be a factor in producing both sexes of parthenogenetic frogs and tadpoles.
7. Genetic data indicate that the normal male is digametic and that there are differences of potency between male and female factors for sex which vary in frogs of the two races and in strains within the race. These differences have been interpreted by Witschi as forming a series of multiple allelomorphs.
THE ACTION OF ALKALIES ON PEPTIDES AND ON KETOPIPERAZINES
Authors: Levene P. A. , Pfaltz M. H. 
Published: May 2004

1. The tripeptide glycyl-levo-alanyl-glycine in solution of either one or ten equivalents of alkali does not undergo racemization on standing.
2. The dipeptide levo-alanyl-glycine under the conditions given in (1) does not undergo racemization.
3. In ketopiperazines, levo-alanyl-glycine anhydride and in levo-prolyl-glycine anhydride under the influence of dilute alkalies, racemization takes place.
4. Racemization in the present experiments was never complete. The degree of racemization seems to depend, on the one hand, on the stability of the ketopiperazine ring; on the other, on the concentration of the alkali.
5. The significance of these observations will depend on the outcome of the work on a larger number of polypeptides and ketopiperazines. The work is now in progress in this laboratory.
PROTEIN FILMS ON COLLODION MEMBRANES
Authors: Hitchcock David I. 
Published: May 2004

1. Collodion membranes of high permeability were found to adsorb weighable amounts of gelatin and egg albumin from solution at 37°C.
2. The effect of protein concentration could be expressed fairly well by a hyperbolic equation proposed by Langmuir for the adsorption of gases by a plane surface, while the usual parabolic adsorption equation of Freundlich did not fit the results.
3. In comparing this effect with solutions of varying pH, it was found there was a decided maximum of adsorption in solutions of isoelectric protein. The effects of acids and salts on the amount of gelatin adsorbed were like those observed by Loeb on the viscosity of gelatin solutions, but opposite in direction. The effects of pH on the amount of adsorbed gelatin and on the fluidity of the gelatin solutions were nearly parallel.
4. Membranes made impermeable by long drying took up very little or no gelatin from solution.
5. In the case of membranes of varying permeability the maximum amount of adherent gelatin increased with the permeability and thickness of the membranes, and appeared to be, within limits, a linear function of the relative pore surface of the membranes as calculated from Poiseuille's law.
6. The film of gelatin greatly decreased the permeability of the membranes, as measured by the flow of water through them. The relative cross-section of the pore openings, as calculated from the permeability measurements, was a linear function of the amount of adherent gelatin. These results led to the conclusion that the gelatin formed a film inside the pores.
GEOTROPISM AND MUSCLE TENSION IN HELIX
Authors: Cole William H. 
Published: May 2004

1. The snail Helix aspersa Müller, is negatively geotropic during the daytime, but positive or indifferent at night.
2. The precision of geotropic orientation is a function of the gravity component acting on the body.
3. The rate of geotropic locomotion is also determined by the gravity component (sine of the angle of inclination).
4. The rate of upward movement is increased 1.51 times at 45° inclination by loading the snail with one-half its weight. No such increase is seen in loaded snails creeping on a horizontal surface.
5. Moderate centrifugation results in orientation and locomotion towards the center of rotation.
6. A response analogous to the homostrophic reflex occurs when a backward pull to right or to left is exerted on the shell. Bilaterally equal tension applied to the shell causes locomotion along a path parallel and opposite to the direction of the pull.
7. All the observations go to show that the stimulus for geotropic orientation and locomotion is tension of the body muscles produced by the downward pull of gravity, and that the stimulus is received by the proprioreceptors of these muscles. Otolith apparatus and analogous organs, when present, may assist in the response, but they do not seem to be requisite in all cases. Since the precision of orientation and the rate of locomotion are functions of the gravity component acting on the body, the muscle tension theory of the geotropic reactions accords fully with Loeb's tropism doctrine for animals.
FERMENTWIRKUNG UND IONENANTAGONISMUS
Authors: Höber Von Rudolf , Schürmeyer Albert 
Published: May 2004

1. Invertase ist salzempfindlich nur in Gegenwart von Kolloiden, wie Gelatine, Albumin, Globulin, Lecithin; ihre Aktivität wird dabei durch die Salze herabgesetzt.
2. An den Komplexen Invertase-Globulin und Invertase-Lecithin lässt sich eine Ionenaequilibrierung von der Art des physiologischen Kationenantagonismus nachweisen; Na und K einerseits, Mg, Ca, Sr, Ba, Al, La andererseits hemmen in gewissen Konzentrationsverhäitnissen einander, so dass bei Einhaltung dieser Verhältnisse die Invertase optimal wirkt.
3. Die Salzhemmung und der Kationenantagonismus fehlen auf der sauren Seite des isoelektrischen Punkts des Globulins und Lecithins.
THE EFFECT OF EXPOSURE PERIOD AND TEMPERATURE ON THE PHOTOSENSORY PROCESS IN CIONA
Authors: Hecht Selig 
Published: May 2004

1. Experiments are presented which show that the latent period in the photosensory response of Ciona is inversely proportional to the duration of the exposure period to light. From this it is found that the velocity of the chemical reaction which determines the latent period is directly proportional to the concentration of photochemical products formed during the exposure period. This is interpreted as showing that the two processes form a coupled photochemical reaction, of which the secondary reaction proceeds only in the presence of products from the primary reaction. This coupling may be a catalysis or a direct chemical relation.
2. Further experiments show that the relation between temperature and the latent period is accurately described by the Arrhenius equation in which µ = 16,200. The precise numerical value of µ tentatively identifies the latent period process as an oxidation reaction which is catalyzed by iron.
3. The photocatalytic properties of certain iron compounds are used as a model for the coupled photochemical reaction suggested for the photosensory mechanism of Ciona and Mya.
THE PHOTOLYSIS OF THE LUMINESCENT GRANULES OF EUCHARIS MULTICORNIS
Authors: Moore A. R. 
Published: May 2004

1. By means of a photographic method a study was made of the photolytic effect of light on the luminescent granules of Eucharis multicornis.
2. The photolytic reaction conforms to the Bunsen-Roscoe law.
3. The velocity of the photolytic reaction is not increased by a rise in temperature.
4. The photolytic reaction proceeds as a first order reaction.
THE SWELLING AND OSMOTIC PRESSURE OF GELATIN IN SALT SOLUTIONS
Authors: Northrop John H. , Kunitz M. 
Published: May 2004

1. The swelling and the osmotic pressure of gelatin at pH 4.7 have been measured in the presence of a number of salts.
2. The effect of the salts on the swelling is closely paralleled by the effect on the osmotic pressure, and the bulk modulus of the gelatin particles calculated from these figures is constant up to an increase in volume of about 800 per cent. As soon as any of the salts increase the swelling beyond this point, the bulk. modulus decreases. This is interpreted as showing that the elastic limit has been exceeded.
3. Gelatin swollen in acid returns to its original volume after removal of the acid, while gelatin swollen in salt solution does not do so. This is the expected result if, as stated above, the elastic limit had been exceeded in the salt solution.
4. The modulus of elasticity of gelatin swollen in salt solutions varies in the same way as the bulk modulus calculated from the osmotic pressure and the swelling.
5. The increase in osmotic pressure caused by the salt is reversible on removal of the salt.
6. The observed osmotic pressure is much greater than the osmotic pressure calculated from the Donnan equilibrium except in the case of AlCl3, where the calculated and observed pressures agree quite closely.
7. The increase in swelling in salt solutions is due to an increase in osmotic pressure. This increase is probably due to a change in the osmotic pressure of the gelatin itself rather than to a difference in ion concentration.
THE ACTIVATION OF STARFISH EGGS BY ACIDS
Authors: Lillie Ralph S. 
Published: May 2004

1. Exposure of unfertilized starfish eggs to dilute solutions of weak acids (fatty acids, benzoic and carbonic acids) in isotonic balanced salt solution causes complete activation with the proper durations of exposure. For each acid the rate of activation (reciprocal of optimum duration) varies with concentration and temperature; at a given temperature and within a considerable range of concentrations (e.g. 0.00075 to 0.004 M for butyric acid), this rate is approximately proportional to concentration. We may thus speak of a molecular rate of action characteristic of each acid.
2. In general the molecular rate of action increases with the dissociation constant and surface activity of the acids. In the fatty acid series (up to caproic), formic acid has the most rapid effect, acting about four times as rapidly as acetic; for the other acids the order is: acetic = propionic ≦ butyric &lt; valeric &lt; caproic. Carbonic acid acts qualitatively like the fatty acids, but its molecular rate of action is only about one-fourteenth that of acetic acid.
3. Hydrochloric and lactic acids are relatively ineffective as activating agents, apparently because of difficulty of penetration. Lactic acid is decidedly the more effective. The action of both acids is only slightly modified by dissolving in pure (isotonic NaCl and CaCl2) instead of in balanced salt solution.
4. The rate of action of acetic acid, in concentrations of 0.002 M to 0.004 M is increased (by 10 to 20 per cent) by adding Na-acetate (0.002 to 0.016) to the solution. The degree of acceleration is closely proportional to the estimated increase in undissociated acetic acid molecules. Activation thus appears to be an effect of the undissociated acid molecules in the external solution and not of the ions. Acetate anions and H ions acting by themselves, in concentrations much higher than those of the solutions used, have no activating effect. The indications are that the undissociated molecules penetrate rapidly, the ions slowly. Having penetrated, the molecules dissociate inside the egg, yielding the ions of the acid.
5. When the rate of activation is slow, as in 0.001 M acetic acid, the addition of Na-acetate (0,008 M to 0.016 M) has a retarding effect, referable apparently to the gradual penetration of acetate ions to the site of the activation reaction with consequent depression of dissociation.
6. An estimate of the CH of those solutions (of the different activating acids) which activate the egg at the same rate indicates that their H ion concentrations are approximately equal. On the assumptions that only the undissociated molecules penetrate readily, and that the conditions of dissociation are similar inside and outside the egg, this result indicates (especially when the differences in adsorption of the acids are considered) that the rate of activation is determined by the CH at the site of the activation reaction within the egg.
THE RELATIONS OF THE INDIVIDUAL AMPULLÆ OF THE SEMICIRCULAR CANALS TO THE INDIVIDUAL EYE MUSCLES
Authors: Maxwell S. S. , Huddleston O. L. 
Published: May 2004

1. The reflex effect of direct mechanical stimulation of the exposed ampulla of the horizontal canal has been graphically recorded for each of the six extrinsic muscles of the eyeball.
2. Stimulation of a horizontal ampulla evokes a strong contraction of the homolateral rectus internus and of the contralateral rectus externus; at the same time the homolateral rectus externus and the contralateral rectus internus relax.
3. A single mechanical stimulus applied to the horizontal ampulla is sometimes followed by a nystagmus resulting from a series of rhythmic contractions of the externus and internus muscles.
4. Excitation of a horizontal ampulla gives rise to weak contractions of the superior and inferior recti and of the two oblique muscles of both eyes, simultaneously with the stronger contractions of the externus and internus respectively.
5. It is pointed out that the small simultaneous contractions of the four muscles just mentioned provide a virtual axis upon which the eyeball rotates. In other words these four act as fixation muscles.
6. It is suggested that some of the abnormal responses to horizontal rotation, seen in clinical cases, are due to the inaction of one or more of the fixation muscles.
THE EFFECT OF PURE PROTEIN SOLUTIONS AND OF BLOOD SERUM ON THE DIFFUSIBILITY OF CALCIUM
Authors: Loeb Robert F. ,   With the Assistance of Emily Nichols.
Published: May 2004

1. A comparative study has been made of the diffusibility of calcium in solutions of crystalline egg albumin, serum globulin, and human blood serum.
2. In all three of these solutions, at pH 7.4, molal Ca concentrations within the membrane are greater than the calcium concentrations in the outside solutions, quite in accordance with the Donnan theory.
3. At pH 7.4, the ratio of
See PDF for Structure
varies directly with the protein concentration whether the solution be one of egg albumin, serum globulin, or blood serum. This is also in accordance with the Donnan theory.
4. On the acid side of the isoelectric point of the proteins, the concentration of Ca outside becomes greater than the concentration in the solution of blood serum or pure protein, as is demanded by the Donnan theory.
5. The magnitude of the Ca ratios on the alkaline and acid sides of the isoelectric points is probably the resultant of the Donnan equilibrium and the formation of complex Ca-protein ions. Northrop and Kunitz have shown the probability of the existence of such ions in the case of Zn++, K+, and Li+, where satisfactory electrodes have been developed for E.M.F. measurements.
ON THE RESPECTIVE PARTS PLAYED BY NEURAL AND HUMORAL INFLUENCES IN ANIMAL REACTIONS
Authors: Sharpey-Schafer E. 
Published: May 2004

1. In the higher animals control of the functions of the body is dual, being partly neural and partly humoral.
2. When the control of any function is single and not dual, it is entirely neural. Exceptions to this statement appear to occur in connexion with the secretion of urine and milk, since these functions have not hitherto been shown to be under direct neural control. The mamma, and perhaps the kidney also, is, however, influenced by certain internal secretions which are themselves subJect both to neural and to humoral control.
3. The functions which are controlled both neurally and humorally are initiated by direct nervous influence: the humoral influence succeeds this.
4. In the lowest organisms possessed of a nervous system there is no evidence of humoral control, and no probability that this could be exercised, since there is no circulatory fluid, and the fluid which bathes the tissue has a composition appreciably the same as that of the environment.
5. It is, therefore, inferred that in all cases in which a dual control exists the neural, which is more rapid in its action, is primary, and the humoral secondary; and that the object of the humoral influence is to continue and prolong the effect of the neural influence, and thus to effect an economy of nervous energy.
STUDIES OF GAS AND ELECTROLYTE EQUILIBRIA IN THE BLOOD
Authors: Hastings A. Baird , Salvesen Harald A. , Sendroy Julius , Van Slyke Donald D. 
Published: May 2004

1. Analyses have been made of the electrolytes and proteins of serum and transudates from human subjects.
2. The distribution ratios of HCO3, Cl, Na, and H+ deviated from unity as predicted by the Gibbs-Donnan law for similar heterogeneous systems.
3. Analyses of serum, and of artificial salt solutions approximating edema fluid in composition, after equilibration across collodion membranes showed distributions similar to those between serum and edema fluid in vivo.
TEMPERATURE AND THE MECHANISM OF LOCOMOTION IN PARAMECIUM
Authors: Glaser Otto 
Published: May 2004

1. Frequency polygons in which the number of observations at each temperature is reduced to a percentage basis while the time factor is represented on a logarithmic scale, indicate that the time required by Paramecium to swim a unit distance at different temperatures varies within definite limits which are constant above 15°. Below 15° the range of variability very possibly is not the same, though probably likewise constant.
2. Logarithmic velocities deduced from mean, maximal, minimal, and modal time classes, when plotted against reciprocals of the absolute temperature, fall respectively on straight lines. These lines are parallel and give µ values of 8,000 above 15° and probably 16,000 below.
3. This implies that the mechanism of locomotion in Paramecium remains essentially unaltered by a rise in temperature from 15° to 30°, and probably remains in a similar sense constant from 6° to 15°.
4. The theoretical interpretation of this result is possible in terms of a catenary series 0 → A → E in which the passages 0 → A and A → E are controlled by two catalysts differing respectively in concentration in different individuals and perhaps at different times in the same individual, but depending for their effective concentration on reactions having temperature coefficients identical with those which at each temperature characterize the biological process under consideration.
A COMPARISON OF BONE GROWTH IN LENGTH WITH BONE GROWTH IN WEIGHT
Authors: Hammett Frederick S. 
Published: May 2004

1. The growth capacity in length of the humerus and femur of male and female albino rats during the growth period from 23 to 150 days of age is less than the growth capacity in weight. This shows that the processes productive of bone strength are more active than those concerned in longitudinal expansion or stature.
2. Growth capacity in length is less affected than is growth capacity in weight by the systemic determinants and the factors incident to sex, weaning, and puberty. Since the findings as a whole are consistent with the assumption that bone growth in length is largely a matter of increase in cell number, while bone growth in weight is largely a matter of increase in cell size and density, the generalization is made that, in the bones at least, growth by increase in cell number is more stable than growth by increase in cell size and density.
3. A stabilization and approximation to a uniform level of growth capacity in both length and weight occurs at the culmination of puberty, which is quite like that taking place in the chemical differentiation at the same time.
4. Bone growth in length is more like body growth in length than bone growth in weight is like body growth in weight.
THE INFLUENCE OF THE INTENSITY OF LIGHT ON THE RATE OF GROWTH AND DURATION OF LIFE OF DROSOPHILA
Authors: Northrop John H. 
Published: May 2004

The duration of the larval and imago periods of Drosophila cultures which had been previously grown in the dark for 200 generations has been determined at various light intensities.
1. The duration of the larval period is shortened slightly at intensities around 2,500 meter candles, but becomes increasingly longer at higher intensities. The larvæ are killed by continuous exposure to light of 7,000 to 10,000 meter candles.
2. The pupæ are killed at intensities greater than 5,000 meter candles.
3. Above 1,000 meter candles the duration of the imago period is rapidly shortened.
4. The duration of life of the imago at different intensities of illumination can be quite accurately predicted by assuming that the light produces an independent "rate of aging" which is proportional to the intensity of the light.
5. The result of short exposure of the imago shows that light does not merely accelerate the normal "rate of aging," and also that the effect is only partially reversible.
Diffuse daylight does not affect the upper temperature limit of growth.
ON SOME GENERAL PROPERTIES OF PROTEINS
Authors: Anson M. L. , Mirsky A. E. 
Published: May 2004

1. The processes of denaturation and coagulation of hemoglobin are like those of other proteins.
2. When hemoglobin is denatured it is probably depolymerized into hemochromogen.
3. When other proteins are denatured they, too, are probably depolymerized. Conversely, native proteins can be regarded as aggregates of denatured proteins.
4. The globins and histones are to be regarded as denatured proteins rather than as a distinct group of proteins.
5. The factors affecting the equilibrium between native and denatured proteins have been considered.
6. A non-polar group is uncovered when a protein is denatured.
7. It has been shown that judged by the two most sensitive tests for the specificity of proteins, it is only when proteins are in the native form that they are highly specific.
THE EFFECT OF THE H ION CONCENTRATION ON THE AVAILABILITY OF IRON FOR CHLORELLA SP
Authors: Hopkins E. F. , Wann F. B. 
Published: May 2004

The data obtained in these experiments indicate clearly that unless the necessary precautions are taken to keep the iron of the culture medium in solution the results obtained by varying the H ion concentration will not represent the true effect of this factor on growth. The availability of iron in nutrient solutions has been the subject of numerous recent investigations and it is now known that iron is precipitated at the lower hydrogen ion concentrations, that the iron of certain iron salts is less likely to be precipitated than that of others, and that certain salts of organic acids tend to keep the iron in solution. In general, ferric citrate seems to be the most favorable source of iron. In addition to chemical precipitation, however, it is also possible for the iron to be removed by adsorption on an amorphous precipitate such as calcium phosphate. As this precipitate is frequently formed when nutrient solutions are made alkaline, this may account for the discordant results reported in the literature as to the availability of certain forms of iron. By omitting calcium from the culture solution iron can be maintained in a form available for growth in alkaline solutions by the addition of sodium citrate. In such solutions the maximum growth of Chlorella occurred at pH 7.5. The alkaline limit for growth has not been established as yet.
In investigating the availability of iron at varying concentrations of the hydrogen ion, changes in the pH value of the solution during the course of an experiment should also be taken into account. This is especially important in unbuffered solutions. The differential absorption of the ions of ammonium salts may cause a marked increase in the hydrogen ion concentration, which in turn will cause an increase in the solubility of iron. In strongly buffered solutions as used in these experiments this effect is slight.