bluuebunny/crossref_metadata_2025_split huggingface dataset:
ON THE INTENSITY-TIME RELATIONS FOR STIMULATION BY ELECTRIC CURRENTS. I
Authors: Blair H. A. 
Published: May 2004

Formulae are derived for the time-intensity relations for stimulation by direct currents using the following hypotheses: first, the current produces an excitatory effect whose rate of growth is proportional to the voltage; and second, the tissue reacts toward the normal state at a rate proportional to the amount of excitation. If p represents the local excitatory process numerically, the hypotheses are represented by the differential equation
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where K and k are constants and V the applied voltage. For the stimulus to be adequate it is assumed that p must be built up to a certain liminal value. It appears as a deduction from the data that this liminal value is a function of the voltage of the form h ± αV where h and α are constants. α is zero or negligible for certain electrodes. αV is a measure of electrotonus or a similar phenomenon. Experimental data are discussed and are shown to agree satisfactorily with the derived formulae for stimulation both at the anode and cathode.
AUTOMATIC RECORDING OF MOVEMENTS OF PLANT ORGANS
Authors: Navez A. E. , Robinson T. W. 
Published: May 2004

An automatic photographic recording apparatus is described. It uses plates sensitized to the red end of the spectrum for recording movements of organs of plants which cannot be photographed in white light. It enables one to obtain two types of pictures:
1. A "standing plate" picture where the successive positions of the organ to be registered are superimposed on the same plate, no motion being imparted to the plate.
2. A "moving plate" picture where, by means of a clock-controlled plate shifter, each successive picture is entirely separate from the preceding one.
PEPSIN ACTIVITY UNITS AND METHODS FOR DETERMINING PEPTIC ACTIVITY
Authors: Northrop John H. 
Published: May 2004

Experimental methods are described for determining the activity of pepsin preparations by means of changes in the viscosity of gelatin, casein, edestin, and powdered milk solutions, and by the rate of formation of non-protein nitrogen from casein and edestin solutions, or by the increase in formol titration of casein, edestin or gelatin.
Activity units for pepsin are defined in terms of these measurements.
THE MECHANISMS OF TROPISTIC REACTIONS AND THE STRYCHNINE EFFECT IN DAPHNIA
Authors: Clarke G. L. , Wolf Ernst 
Published: May 2004

1. Experiments with strychnine were performed to test two assumptions important in the development of a theory for the mechanisms involved in the tropisms exhibited by Daphnia.
2. After a brief interval in strychnine solution Daphnia exhibits a reversal of the primary sign (a) of phototropism, from negative to positive; and (b) of galvanotropism, from anodic to cathodic. In both cases the orientation of the body remains the same.
3. The mechanism responsible for the sign of phototropism and galvanotropism in Daphnia is therefore distinct from that underlying orientation.
4. Evidence is obtained indicating that changes in sign of tropism, produced by changes in illumination or by subjection to strychnine, involve the control of antagonistic muscles in the swimming appendages which are reciprocally innervated.
THE EFFECTS OF RADIATIONS ON BIOLOGICAL SYSTEMS
Authors: Hussey Raymond , Thompson William R. , Tennant Robert , Campbell Nancy DuVal 
Published: May 2004

The effect of high-frequency x-ray irradiation in prolongation of the larval stage of Drosophila melanogaster has been studied further, and evidence presented of the attainment of a maximum effect followed by a decrease to an almost level plateau in the course curve of average (median) prepupal period (ϕ) as a function of the period of irradiation (t) under otherwise fixed conditions. The variation of effects of the experimental treatment with age of the larvae at the time of irradiation has been demonstrated in both control and irradiated lots, and a strikingly decreased effect observed when ventilation was not supplied as usual.
Means of employment of a living system of this type as an indicator of effectiveness of radiation as in phantom depth or other distributional experiments have been presented and their use illustrated.
FACTORS INVOLVED IN THE USE OF ORGANIC SOLVENTS AS PRECIPITATING AND DRYING AGENTS OF IMMUNE SERA
Authors: Merrill Malcolm H. , Fleisher Moyer S. 
Published: May 2004

1. In concentrations of 70 to 75 per cent the organic solvents methyl, ethyl, and propyl alcohols, and acetone cause complete precipitation of serum proteins and produce maximum loss in solubility. We have referred to this concentration range as the critical concentration.
2. As the concentration of the solvents is increased from about 75 per cent precipitation continues complete but loss in solubility progressively decreases until at all concentrations above about 87 per cent the precipitates formed at room temperature are completely soluble.
3. The degree of resolubility of the precipitates formed even in these high concentrations of the organic solvent decreases as the temperature is raised and as the duration of exposure is increased.
4. At 5°C. the precipitates formed in all concentrations of these organic solvents are completely resoluble. Also these solvents exert maximum precipitating effect at lower temperature.
5. Maximum precipitating effect by these organic solvents occurs at about pH 6.0 precipitation becoming progressively less as the pH value is altered either way from this point.
6. The more concentrated the serum, the greater the proportion of protein present that will be precipitated by any given concentrations of organic solvent.
7. A method for preparing dry immune sera has been given. Such dried sera have been extracted with a number of organic compounds without loss in solubility or antibody activity.
THE VISUAL INTENSITY DISCRIMINATION OF THE HONEY BEE
Authors: Wolf Ernst 
Published: May 2004

1. Bees respond by a characteristic reflex to a movement in their visual field. By confining the field to a series of parallel stripes of different brightness it is possible to determine at any brightness of one of the two stripe systems the brightness of the second at which the bee will first respond to a displacement of the field. Thus intensity discrimination can be determined.
2. The discriminating power of the bee's eye varies with illumination in much the same way that it does for the human eye. The discrimination is poor at low illumination; as the intensity of illumination increases the discrimination increases and seems to reach a constant level at high illuminations.
3. The probable error of
See PDF for Equation
decreases with increasing I exactly in
the same way as does
See PDF for Equation
itself. The logarithm of the probable error
of ΔI is a rectilinear function of log I for all but the very lowest intensities. Such relationships show that the measurements exhibit an internal self-consistency which is beyond accident.
4. A comparison of the efficiency of the bee's eye with that of the human eye shows that the range over which the human eye can perceive and discriminate different brightnesses is very much greater than for the bee's eye. When the discrimination power of the human eye has reached almost a constant maximal level the bee's discrimination is still very poor, and at an illumination where as well the discrimination power of the human eye and the bee's eye are at their best, the intensity discrimination of the bee is twenty times worse than in the human eye.
ELECTROKINETIC PHENOMENA
Authors: Daniel Janet 
Published: May 2004

1. The electrophoretic velocities of gelatin-, egg-albumin-, and gliadin-covered quartz particles in various alcohol-water solutions are, within the limits employed in usual experimental procedures, proportional to the field strength.
2. The electrophoretic mobilities of small, irregularly shaped quartz particles covered with an adsorbed film of protein in alcohol-water solutions are equal to the electroosmotic mobilities of the liquid past similarly coated flat surfaces. Hence the size and shape of such particles does not influence their mobilities, which depend entirely on the protein film.
3. The corrected mobility and hence presumably the charge of gelatin-covered quartz particles in solutions containing 35 per cent ethyl alcohol is proportional to the combining power of the gelatin; therefore the gelatin is adsorbed with the active groups oriented toward the liquid. The same is true in 60 per cent alcohol.
4. The charge calculated by means of the Debye-Henry approximation from the mobility of gelatin in solutions containing up to 35 per cent ethyl alcohol is, in the neighborhood of the isoelectric point, proportional to the combining power of the gelatin. Therefore the dielectric constant and the viscosity of the bulk of the medium may be used in the Debye-Henry approximation
Q = 6 π η r vm (1 + κ r)
to predict changes in charge from mobility.
5. In the neighborhood of the isoelectric point gelatin is probably completely ionized in buffered ethyl alcohol-water mixtures up to 60 per cent alcohol.
6. In the presence of ethyl alcohol the isoelectric point of gelatin is shifted toward smaller hydrogen ion activities. This shift, like that caused by alcohol in the isoelectric points of certain amino acids, is approximately linearly related to the dielectric constant of the medium.
THE KINETICS OF PENETRATION
Authors: Osterhout W. J. V. 
Published: May 2004

An organic potassium salt, KG, passes from an aqueous phase, A, through a non-aqueous layer, B, into a watery solution, C. In C it reacts with CO2 to form KHCO3. The ionic activity product (K) (G) in C is thus kept at such a low level that KG continues to diffuse into C after the concentration of potassium becomes greater in C than in A. Hence potassium accumulates in C, the osmotic pressure rises, and water goes in. A steady state is eventually reached in which potassium and water enter C in a constant ratio.
The rate of entrance of potassium (with no water penetrating into C) may fall off in a manner approximately exponential. But water enters and may produce an exponential decrease in concentration. This suggests that the kinetics may be treated like that of two consecutive monomolecular reactions. Calculations made on this basis agree very well with the observed values.
The rate of penetration appears to be proportional to the concentration gradient of KG in the non-aqueous layer and in consequence depends upon the partition coefficients which determine this gradient.
Exchange of ions (passing as such through the non-aqueous layer) does not seem to play an important rôle in the entrance of potassium.
The kinetics of the model may be similar to that of living cells.
"GROWTH-PROMOTING SUBSTANCE" AND ELONGATION OF ROOTS
Authors: Navez A. E. 
Published: May 2004

The vertical elongation of normal roots of Lupinus seedlings proceeds at constant rate over periods of 4 to 5 hours.
The decapitation of a root stops its elongation for a variable length of time, followed by a period of renewed elongation at a rate lower than that of the normal root.
The tipping of the decapitated root with a tip of a coleoptile of Zea induces a decrease in the rate of elongation of the root.
The same effect can be obtained with the diffusate from tips of coleoptile of Avena and to a lesser extent with diffusate of root tips.
The reduction in the rate of elongation of the root determined by diffusate from the lower half of the tip of a coleoptile placed horizontally is more pronounced than the inhibition elicited by the diffusate of the upper half of the same tip.
Various experiments with the diffusate of tips support the idea that under the conditions used the growth-promoting substance of the coleoptile tip or root tip inhibits the elongation of the decapitated root.
THE DIGESTION AND INACTIVATION OF MALTASE BY TRYPSIN AND THE SPECIFICITY OF MALTASES
Authors: Tauber Henry , Kleiner Israel S. 
Published: May 2004

1. The maltase of saliva and that of E. coli (B. coli communis) hydrolyze maltose but not α-methylglucoside or sucrose and are therefore to be considered glucomaltases.
2. Maltase is rapidly and completely inactivated and digested by trypsin.
ON THE RELATION BETWEEN MEASUREMENTS OF INTENSITY DISCRIMINATION AND OF VISUAL ACUITY IN THE HONEY BEE
Authors: Wolf Ernst 
Published: May 2004

1. Bees respond by a characteristic reflex to a movement of their visual field. By confining the field to a series of parallel stripes of two alternating different brightnesses it is possible to determine for any width of stripe, at any brightness of one of the two sets of stripes, the brightness of the second at which the bee will first respond to a displacement of the field. Thus the relations between visual acuity and intensity discrimination can be studied.
2. For each width of stripe and visual angle subtended by the stripe the discrimination power of the bee's eye for different brightnesses was studied. For each visual acuity the intensity discrimination varies with illumination in a characteristic, consistent manner. The discrimination is poor at low illuminations; as the intensity of illumination increases the discrimination increases, and reaches a constant level at high illuminations.
3. From the intensity discrimination curves obtained at different visual acuities, visual acuity curves can be reconstructed for different values of ΔI/I. The curves thus obtained are identical in form with the curve found previously by direct test for the relation between visual acuity and illumination.
ANALYSIS OF THE GEOTROPIC ORIENTATION OF YOUNG RATS. VII
Authors: Crozier W. J. , Pincus G. 
Published: May 2004

The intraperitoneal injection of standard young rats of race A with 2/5 cc. of adrenalin chloride 1:50,000 results in increased speed of geotropically oriented creeping upon an inclined surface. It was expected that the effect of such increased frequency of stepping must be analogous to that due to imposition of added loads carried by the rats during geotropic progression. This is verified. The curve connecting θ with log sin α is distorted, under adrenalin, so as to be comparable to that obtained with an added mass of approximately 2.5 gm. upon the young rat's saddle; the threshold slope of surface for orientation is accordingly lowered, from α = 20° to α = 12.5°; at the new threshold slope of surface the mean orientation angle θ is the same as in the absence of adrenalin at the corresponding threshold slope of surface.
The total variation of performance is significantly increased in the injected rats, and at given slope of surface the variation is slightly increased. The proportionate modifiable variation of response is quite unaffected by the distortion of the θ – α curve, and is the same as in standard young A rats untreated or carrying additional loads.
It is pointed out that for the consideration of the problem as to whether a given experimental treatment, or a given natural situation, affects in any way the variation of performance of a living system, it is necessary to obtain indices of variability which involve the expression of variation of performance as a function of measured conditions governing the performance.
THE INACTIVATION OF BACTERIOPHAGE BY MERCURY BICHLORIDE; THE REACTIVATION OF BICHLORIDE-INACTIVATED PHAGE
Authors: Krueger A. P. , Baldwin D. M. 
Published: May 2004

1. The inactivation of antistaphylococcus bacteriophage suspended in infusion broth at pH 7.6 and 22°C. by HgCl2 proceeds according to the equation dP/dt = k [HgCl2] [Po – Pi] over the range studied.
2. This inactivation can be reversed by precipitation of Hg++ with H2S. In the present experiments the inactivation was carried out until only some 5 per cent of the initial phage remained active. After reactivation the [P] had increased to 100 per cent of the initial [P].
THE EFFECT OF WATER CONTENT UPON THE RATE OF HEAT DENATURATION OF CRYSTALLIZABLE EGG ALBUMIN
Authors: Barker H. Albert 
Published: May 2004

1. The denaturation rate of partially dried crystallizable egg albumin is greatly decreased by decreasing its water content.
2. The temperature of denaturation, defined as the temperature at which half of the protein becomes insoluble in distilled water after a definite time of heating, is a linear function of the relative humidity with which the protein is in equilibrium.
3. By applying the Arrhenius equation it is shown that the rate of heat denaturation at a given temperature is an exponential function of the relative humidity.
4. The application of the observed relations to the analysis of the mechanism of thermal death of microorganisms is suggested.
5. The water content of native and heat-denatured egg albumin is determined as a function of the relative humidity of water vapor. It is shown that the heat-denatured modification takes up approximately 80 per cent as much water at all relative humidities as does native egg albumin.
THE ACTION OF THE PLANT GROWTH HORMONE
Authors: Bonner James 
Published: May 2004

1. Sections of Avena coleoptiles are found to show a considerable elongation when suspended in solutions of growth substance.
2. This elongation does not take place in the absence of O2 and is inhibited by KCN and phenylurethane.
3. The rate of respiration of sections of coleoptiles is increased by the addition of growth substance in concentrations which cause growth. High concentrations of growth substance inhibit growth and also respiration.
4. The increase in respiration is inhibited by KCN and phenylurethane in the concentrations which inhibit normal respiration. These concentrations are the same as those which inhibit growth.
5. From 2, 3, and 4, it seems possible that the increase in respiration caused by growth substance may be an essential part of its action in growth.
ELECTRICAL RESPONSES FROM LATERAL-LINE NERVES OF FISHES. III
Authors: Hoagland Hudson 
Published: May 2004

Evidence indicates that lateral-line fibers, other than those mediating the "spontaneous" activity of the lateral-line receptors, are brought into play in response to pressure stimuli in catfish and in trout.
The distribution and mode of stimulation of mechanoreceptors along the lateral-lines of trout and catfish are discussed in relation to the natural activities of these forms.
ABSORPTION OF PEPSIN BY CRYSTALLINE PROTEINS
Authors: Northrop John H. 
Published: May 2004

Crystalline proteins, such as edestin or melon globulin, remove pepsin from solution. The pepsin protein is taken up as such and the quantity of protein taken up by the foreign protein is just equivalent to the peptic activity found in the complex. The formation of the complex depends on the pH and is at a maximum at pH 4.0.
An insoluble complex is formed and precipitates when pepsin and edestin solutions are mixed and the maximum precipitation is also at pH 4.0. The composition of the precipitate varies with the relative quantity of pepsin and edestin. It contains a maximum quantity of pepsin when the ratio of pepsin to edestin is about 2 to 1. This complex may consist of 75 per cent pepsin and have three-quarters of the activity of crystalline pepsin itself. The pepsin may be extracted from the complex by washing with cold N/4 sulfuric acid. If the complex is dissolved in acid solution at about pH 2.0 the foreign protein is rapidly digested and the pepsin protein is left and may be isolated.
The pepsin protein may be identified by its tyrosine plus tryptophane content, basic nitrogen content, crystalline form and specific activity.
ELECTRICAL RESPONSES FROM THE LATERAL-LINE NERVES OF FISHES
Authors: Hoagland Hudson 
Published: May 2004

The spontaneous discharge of impulses from the lateral-line nerves of trout and catfish has been examined.
1. Broken endings of nerve fibers supplying receptors of the lateral-lines of trout and catfish may be the source of a repetitive discharge of nerve impulses.
2. This injury discharge occurs more frequently in trout and may mask the spontaneous discharge from the receptor cells. Experiments indicate that the latter discharge is not the result of injury.
3. The injury discharge ceases in from 10 to 15 minutes. The spontaneous receptor discharge in trout may continue for an hour if the circulation remains intact. The receptor response also fails in from 10 to 15 minutes after failure of the circulation.
4. The receptor discharge, the injury discharge, or the summed discharges frequently become synchronized. The excitability of the fibers of the nerve trunk appears to vary synchronously, so that nerve impulses initiated in fibers from tactile receptors not contributing to the spontaneous discharge can be conducted only during the part of the cycle occupied by the spontaneous discharge.
MOLECULAR WEIGHT, MOLECULAR VOLUME, AND HYDRATION OF PROTEINS IN SOLUTION
Authors: Kunitz M. , Anson M. L. , Northrop John H. 
Published: May 2004

1. The gram molecular weight of a substance may be calculated from the osmotic pressure of its solution.
2. The radius of the hydrated molecule and, hence, the gram molecular volume of the hydrated solute may be determined from diffusion measurements. The hydration of the molecules may, therefore, be calculated from osmotic pressure and diffusion measurements.
3. Hydration may also be determined by viscosity measurements. Hydration of crystalline hemoglobin, crystalline trypsin, and gelatin have been determined by these methods and found to be as follows:
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THE EQUILIBRIA BETWEEN NATIVE AND DENATURED HEMOGLOBIN IN SALICYLATE SOLUTIONS AND THE THEORETICAL CONSEQUENCES OF THE EQUILIBRIUM BETWEEN NATIVE AND DENATURED PROTEIN
Authors: Anson M. L. , Mirsky A. E. 
Published: May 2004

The denaturation of hemoglobin by salicylate in neutral solution is completely reversible.
There is a mobile equilibrium between native and denatured hemoglobin in neutral salicylate solution. The higher the salicylate concentration the greater is the percentage denaturation.
When there is a mobile equilibrium between the native and denatured forms of a protein, denaturation is caused by the addition of any substance which has a greater affinity for the denatured than for the native form.
Theoretically the heat of denaturation must vary with the denaturing agent and must depend on the heat of combination of the denaturing agent with the protein.