bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
THE EFFECT OF CYSTINE AND GLYCOCOLL ON THE OXIDATION OF SODIUM LACTATE BY HYDROGEN PEROXIDE
Authors: Ray George B. 
Published: May 2004

The rate of production of CO2 from sodium lactate when treated with H2O2 may be increased by the addition of a compound containing a sulfhydryl group, i.e. cystine.
A small part of this increase in rate of CO2 is due to the action of the amino group as shown by the action of glycocoll.
The results tend to show that the mode of action of H2O2 is one of dehydrogenation and that the action of the cystine is comparable to the Atmungskörper of Meyerhof.
ON STEREOTROPISM IN TENEBRIO LARVÆ
Authors: Crozier W. J. 
Published: May 2004

Larvæ of Tenebrio while creeping show homostrophic responses, and stereotropic orientation to lateral contacts. Homostrophic orientation is inhibited by stereotropism. Both depend upon the anterior portion of the central nervous system. Stereotropic orientation due to unilateral contact, particularly at the anterior end, persists briefly after the cessation of the contact.
Equal posterior bilateral contact of the body obliterates stereotropic bending. Unequal posterior bilateral contacts lead to orientation through an angle roughly proportional to the differences in contact areas. Functional symmetry in such responses is not disturbed by asymmetrical distribution of the body "hairs."
The stereotropic orientation undergoes reversal of direction, central in origin, when the stimulation is sufficiently intense.
Stereotropic response, leading to maintained lateral contact with a surface or to bending when the end of such a surface has been passed, is inhibited by a definite intensity of light.
These findings (1) round out the demonstration that stereotropism is truly of a tropistic character, and (2) make possible the understanding of conduct in a case involving the participation of contact stimulation, phototropism, temperature, and homostrophy.
NUTRITIONAL STUDIES ON THE CONFUSED FLOUR BEETLE, TRIBOLIUM CONFUSUM DUVAL
Authors: Chapman Royal N. 
Published: May 2004

The confused flour beetle (Tribolium confusum) was chosen for this study because it lives in a food which ordinarily contains no living organisms. The death rates are greater in cultures which are handled daily than in those which are not handled but when all are handled alike the results are comparable.
The results from experiments with individual beetles in various kinds of flour were plotted with instars (larval stages) on the ordinate and time in days on the abscissa, using the results from control experiments in wheat flour to determine the length of the various instars from an "x = y" formula. The curves of development were found to be straight lines throughout all but the last instar. The curve for the last instar during which the larva transformed deviated from the straight line in certain foods, notably rice flour.
When mass cultures were used the death and transformation curves were plotted for each synthetic food. A comparison of the curves from wheat flour and the synthetic foods shows that the first parts of the curves are very much alike in all cases and that a few resemble the control in every respect except that the transformation curve has been moved back for a considerable time.
The death curves for the mass cultures are not smooth but show sudden increase in death at approximately the times of molting. These curves may therefore be compared with the records from individual beetles.
CHANGES IN THE STABILITY AND POTENTIAL OF CELL SUSPENSIONS
Authors: Eggerth Arnold H. 
Published: May 2004

1. Human and sheep erythrocytes, when placed in 0.01 N buffer solutions at reactions more acid than pH 5.2, undergo a progressive change in potential, becoming less electronegative or more electropositive. This change usually occurs within 2 hours at ordinary room temperatures. It did not occur when rabbit erythrocytes were used.
2. This change is due primarily to the liberation of hemoglobin from some of the cells.
3. Hemoglobin, even in very low concentrations, markedly alters the potential of erythrocytes in the more acid reactions. This is due to a combination between the electropositive hemoglobin and the erythrocytes. The effect of the hemoglobin is most marked in the more acid solutions; it occurs only on the acid side of the isoelectric point of the hemoglobin.
4. The isoelectric point of erythrocytes in the absence of salt, or in the presence of salts having both ions monovalent, occurs at pH 4.7. This confirms the observations of Coulter (1920–21). Divalent anions shift the isoelectric point to the acid side.
5. The effect of salts on the potential of erythrocytes is due to the ions of the salts, and is analogous in every way to the effect of salts on albumin-coated collodion particles, as discussed by Loeb (1922–23).
THE AGGLUTINATION OF RED BLOOD CELLS
Authors: Northrop John H. , Freund Jules 
Published: May 2004

1. Unsensitized sheep cells suspended in sugar solutions are agglutinated by electrolytes whenever the potential is depressed to 6 millivolts or less, except in the case of MgCl2 or CaCl2.
2. With these salts no agglutination occurs although there is practically no potential. The presence of these salts prevents acid agglutination. This is presumably due to a decrease in the "cohesion" between the cells.
3. Cells which have been sensitized with specific antibody, ricin, colloidal stannic hydroxide, or paraffin oil, are agglutinated whenever the potential is decreased below about 12 millivolts.
4. The agglutination by electrolytes is therefore primarily due to a decrease in the potential whereas agglutination by immune serum, ricin, etc., is due primarily to an increase in the critical potential.
WAVE LENGTH OF LIGHT AND PHOTIC INHIBITION OF STEREOTROPISM IN TENEBRIO LARVÆ
Authors: Crozier W. J. 
Published: May 2004

A definite intensity of white light is required (about 136 m.c.) to produce negative phototropic orientation of creeping Tenebrio larvæ away from contact with a vertical glass surface. This gives a measure of stereotropism in terms of phototropism, or reciprocally.
The effectiveness of light for the suppression of stereotropism varies with wave length. It is therefore simple to obtain a measure of the relation between wave length and stimulating efficiency in this case of phototropic orientation.
By determinations of the minimal energy required to inhibit stereotropism with different regions of the spectrum, it is found that the maximum effectiveness is sharply localized in the neighborhood of 535µµ.
The curve connecting stimulating efficiency with wave length, while giving a picture of the effective absorption by the photosensory receptors, probably does not permit accurate characterization of the essential photosensitive material.
THE EFFECT OF POTASSIUM ON THE ACID METABOLISM OF SURVIVING SKELETAL AND CARDIAC MUSCLES OF THE FROG
Authors: Griffith Fred R. 
Published: May 2004

The potassium contraction of skeletal muscle and relaxation of cardiac muscle have been correlated with the carbon dioxide and total acid production of these tissues.
1. The immersion of surviving sartorius muscles of the frog in isotonic potassium chloride solution causes a marked increase in the rate of acid production.
2. It is probable that carbon dioxide is the principal acid involved in the above effect.
3. The immersion of surviving cardiac muscle of the frog in isotonic potassium chloride solution causes a pronounced depression in the rate of survival acid production.
4. Reasons are given for believing that these changes in metabolism may be independent of the stimulation and inhibition of contraction which potassium simultaneously produces in these tissues.
THE ALKALINE ISOPOTENTIAL POINT OF THE BACTERIAL CELL
Authors: Winslow C.-E. A. , Shaughnessy H. J. 
Published: May 2004

Irregularities in migration velocity of bacterial cells in the highly alkaline solutions are due to the buffering effect of the cells upon the immediately adjacent zone of menstruum. Consistent results can be obtained by shaking the suspension thoroughly before placing it in the electrophoretic cell.
When observed in this way both Bacillus cereus and Bacterium coli show an isopotential point near pH 13.5, that for Bacillus cereus being slightly below, and that for Bacterium coli slightly above this point. At more alkaline reactions the cells acquire a positive charge which increases with further increase in pH to very high values.
CRITICAL THERMAL INCREMENT FOR THE MOVEMENT OF OSCILLATORIA
Authors: Crozier W. J. , Federighi H. 
Published: May 2004

In a species of Oscillatoria exhibiting movement of type suitable for exact measurement the velocity of linear translatory motion is found to be controlled by the temperature (6 – 36°C.) in accordance with Arrhenius' equation for irreversible reactions. The value of the critical increment (µ) is 9,240. The extreme variates in series of measurements at different temperatures yield the same value of µ. The velocity of movement is therefore regarded as determined by the velocity of an underlying chemical process, controlled by the temperature and by the amount of a substance (? catalyst) whose effective quantity at any moment varies within definite limits in different filaments of the alga.
On the basis of its temperature characteristic the locomotion of Oscillatoria is compared with certain other processes for which this constant is calculated.
PHOTOTROPIC CIRCUS MOVEMENTS OF LIMAX AS AFFECTED BY TEMPERATURE
Authors: Crozier W. J. , Federighi H. 
Published: May 2004

1. The theory of animal phototropism requires for particular instances a knowledge of the action of light as exerted through each of two bilaterally located receptors functioning singly. The measurement of "circus movements" which this involves must be concerned with such aspects of the reaction as are demonstrably dependent upon the effect of light.
2. The negatively phototropic slug Limax maximus exhibits very definite and continuous circus movement under vertical illumination when one eye-tentacle has been removed. The amplitude of the circling movement, measured in degrees deflection per cm. of path as an index of maintained differential tonus, is intimately related to the concurrent velocity of creeping. Analysis of the orienting mechanism is facilitated by the fact that in gasteropods such as Limax the animal creeps by means of the pedal organ, but orients (turns) by a totally distinct set of muscles in the dorsal and lateral regions of the body wall.
3. The expression of the phototropic orienting tendency, with illumination constant, is greatly influenced by the temperature. Above a zone centering at 15°, the amplitude of turning (degrees per cm. of path) is determined by the temperature in accurate agreement with Arrhenius' equation for chemical reaction velocity, with the critical increment µ = 16,820; and the rate of creeping is progressively less as the temperature rises, µ for its reciprocal being 10,900. Below 15°, the velocity of creeping becomes less the the lower the temperature, µ being again 16,800; while the amplitude of orientation is limited merely by the velocity of creeping, its reciprocal being directly proportional thereto.
4. Measurements of Limax circus movements in terms of turning deflection as function of light intensity must therefore be carried out at a temperature well above 15°.
5. The analysis provides a gross physical model of how an end-result may be influenced by temperature according to the effect of temperature upon each of several interconnected processes when the "temperature vs. effect" curves for these processes dynamically intersect.
6. It is pointed out that a certain type of unpredictability (quantative variability) in animal behavior under "normal" natural conditions probably results from dynamic equilibrium there obtaining between diverse mechanisms competing for effector control (in the present case, the creeping mechanism and that for turning, in the range 14–16°C.). It follows that the unraveling of the elements of conduct necessitates experimentation under diverse abnormal conditions favoring individual mechanism of response.
SOME PHYSIOLOGICAL ACTIONS OF CYANIDES
Authors: Bodine Joseph Hall 
Published: May 2004

1. The physiological actions of HCN and its salts appear to be due (a) to the ease with which HCN molecules penetrate living cells and then ionizing, exert their influence by means of H ions and CN ions; (b) to the weakness of HCN as an acid, which permits at neutrality or at even slight alkalinity the presence of a considerable amount of free HCN molecules in the presence of their salts; (c) to specific effects occasioned by its chemical activity.
2. The order of resistance of various protozoans to HCN resembles that of the same protozoa to CO2 and to H2S, but is the reverse of their resistance to mineral acids.
3. HCN in acid, neutral, or slightly alkaline media produces intracellular acidity because of the rapid penetration of HCN molecules into the cell.
4. HCN acts specifically on certain species of protozoa, the order of resistance of Paramecia being Paramecium caudatum &gt; Paramecium mullimicronucleatum &gt; Paramecium aurelia &gt; Paramecium bursaria.