bluuebunny/crossref_metadata_2025_split huggingface dataset:
THEORY AND MEASUREMENT OF VISUAL MECHANISMS
Authors: Crozier W. J. , Holway A. H. 
Published: May 2004

Measurements of ΔI as a function of retinal area illuminated have been obtained at various levels of standard intensity I1, using "white" light and light of three modal wave-lengths (λ465, 525, 680), for monocular stimulation and for simultaneous excitation of the two eyes ("binocular"), using several methods of varying (rectangular) area and retinal location, with control of exposure time.
For data homogeneous with respect to method of presentation,
log ΔIm = -Z log A + C,
where ΔI = Ĩ2 – I1, A is area illuminated, and C is a terminal constant (= log ΔIm for A = 1 unit) depending on the units in which ΔI and A are expressed, and upon I1.
The equation is readily deduced on dimensional grounds, without reference to specific theories of the nature of ΔI or of retinal area in terms of its excitable units. Z is independent of the units of I and A. Experimentally it is found to be the same for monocular and binocular excitations, as is to be expected. Also as is expected it is not independent of λ, and it is markedly influenced by the scheme according to which A is varied; it depends directly upon the rate at which potentially excitable elements are added when A is made to increase.
For simultaneous excitation of the two eyes (when of very nearly equivalent excitability), ΔĪB is less than for stimulation of either eye alone, at all levels of I1, A, λ. The mean ratio (ΔĪL + ΔĪR)/2 to ΔIB was 1.38. For white light, doubling A on one retina reduces ΔIm in the ratio 1.21, or a little less than for binocular presentation under the same conditions. These facts are consistent with the view that the properties of ΔI are quantitatively determined by events central to the retina.
The measure σ1ΔI of organic variation in discrimination of intensities and ΔIm are found to be in simple proportion, independent of I1, A, λ (and exposure time). Variability (σ1ΔI) is not a function of the mode of presentation, save that it may be slightly higher when both retinas are excited, and its magnitude (for a given level of ΔIm) is independent of the law according to which the adjustable intensity I2 is instrumentally controlled.
CALCULATIONS OF BIOELECTRIC POTENTIALS
Authors: Osterhout W. J. V. 
Published: May 2004

Interest in the study of Halicystis and of Valonia has been stimulated by discoveries of marked contrasts and striking similarities existing side by side. This is illustrated by new experiments with the alkali metals and alkaline earths.
In Halicystis the apparent mobilities of K+, Rb+, Cs+, and Li+ (calculated by means of Henderson's equation from changes in P.D. produced by replacing sea water by a mixture of equal parts of sea water and 0.6 M of various chlorides) are as follows, uK, = 16, uRb = 16, uCs = 4.4, and uLi = 0.2; uNa is taken as 0.2. These values resemble those in Valonia except that in the latter uCs is about 0.2.
No calculation is made for uNHNH4, because in these experiments even at low pH so much NH3 is present that the sign of the P.D. may reverse. This does not happen with Valonia. According to Blinks, NH4+ at pH 5 in low concentrations acts like K+.
The calculation gives uMg = 1.9 which is similar to the value found for Valonia.
No calculation can be made for CaCl2 since it produces protoplasmic alterations and in consequence Henderson's equation does not apply. This differs from Valonia.
Evidently these plants agree closely in some aspects of electrical behavior but differ widely in others.
TEMPERATURE AND CRITICAL ILLUMINATION FOR REACTION TO FLICKERING LIGHT
Authors: Crozier W. J. , Wolf Ernst 
Published: May 2004

For the teleosts Xiphophorus montezuma, Platypoecilius maculatus, and their F1 hybrids the temperature characteristics (µ in Arrhenius' equation) are the same for the shift of the low intensity and the high intensity segments of the respective and different flicker response contours (critical intensity I as a function of flash frequency F, with light time fraction constant, at 50 per cent). The value of µ is 12,500 calories or a very little less, over the range 12.5 to 36°. This shows that 1/I can be understood as a measure of excitability, with F fixed, and that the excitability is governed by the velocity of a chemical process common to both the classes of elements represented in the duplex performance curve (rods and cones).
It is accordingly illegitimate to assume that the different shapes of the rod and cone branches of the curves are determined by differences in the chemical mechanisms of excitability. It is also forbidden to assume that the differing form constants for the homologous segments in the curves for two forms (X. and P.) are the reflections of a difference in the chemical factors of primary excitability. These differences are determined by statistical factors of the distribution of excitabilities among the elements implicated in the sensory effect vs. intensity function, and are independent of temperature and of the temperature characteristic.
It must be concluded that the physicochemical nature of the excitatory process cannot be deduced from the shape of the performance contour.
The form constants (σ'log I and Fmax.) for F vs. log I are specifically heritable in F1, although µ is here the same as for X. and P. In an intergeneric cross one cannot in general expect Mendelian simplicity of segregation in subsequent generations, and in the present case we find that F2 individuals are indistinguishable from F1, both as regards F vs. log I and as regards the variation of I within a group of 17 individuals. The result in F2 definitely shows, however, that certain specific statistical form constants for the F-log I contour are transmissible in inheritance. It is pointed out that there thus is provided an instance in which statistical (distribution) factors in performance characteristics involving the summating properties of assemblages of cellular units are heritable in a simple manner without the implication of detectable differences in chemical organization of the units involved. This has an important bearing upon the logic of the theory of the gene.
THE CHEMISTRY OF HUMAN SKIN
Authors: Wilkerson Vernon A. 
Published: May 2004

1. The electrophoretic activity of particles of human skin in distilled water and different concentrations of salt solutions has been studied. The electrokinetic potential and the charge density were determined and comparisons made with results obtained by electroendosmosis.
2. The electrokinetic potential is ultimately decreased if sufficient salt is added. The order of inhibition is Al &gt; Ca &gt; Ba &gt; K &gt; Na.
3. The lyotrophic series Li &gt; Na &gt; K &gt; Rb and Cl &gt; I &gt; Br express respectively the comparative effect of the monovalent cations and anions upon the electrokinetic potential of the skin.
4. Since both electrophoresis and electroendosmosis are dependent upon the electrokinetic potential, it follows from the results obtained, that the greatest rate of flow through the human skin under the force of an applied electrical current would be given by concentrations of neutral salts between 0.0001 M and 0.0002 M.
THE REACTIONS OF DENATURED EGG ALBUMIN WITH FERRICYANIDE
Authors: Anson M. L. 
Published: May 2004

The following facts have been established experimentally.
1. In the presence of the synthetic detergent, Duponol PC, there is a definite reaction between dilute ferricyanide and denatured egg albumin. 0.001 mM of ferrocyanide is formed by the oxidation of 10 mg. of denatured egg albumin despite considerable variation in the time, temperature, and pH of the reaction and in the concentration of ferricyanide.
2. If the concentration of ferricyanide is sufficiently high, then the reaction between ferricyanide and denatured egg albumin in Duponol solution is indefinite. More ferrocyanide is formed the longer the time of reaction, the higher the temperature, the more alkaline the solution, and the higher the concentration of ferricyanide.
3. Denatured egg albumin which has been treated with formaldehyde or iodoacetamide, both of which abolish the SH groups of cysteine, does not reduce dilute ferricyanide in Duponol PC solution.
4. Cysteine is the only amino acid which is known to have a definite reaction with ferricyanide or which is known to react with dilute ferricyanide at all. The cysteine-free proteins which have been tried do not reduce dilute ferricyanide in Duponol PC solution.
5. Concentrated ferricyanide oxidizes cystine, tyrosine, and tryptophane and proteins which contain these amino acids but not cysteine. The reactions are indefinite, more ferrocyanide being formed, the higher the temperature and the concentration of ferricyanide.
6. The amount of ferrocyanide formed from denatured egg albumin and a given amount of ferricyanide is less in the absence than in the presence of Duponol PC.
7. The amount of ferrocyanide formed when denatured egg albumin reacts with ferricyanide in the absence of Duponol PC depends on the temperature and ferricyanide concentration throughout the whole range of ferricyanide concentrations, even in the low range of ferricyanide concentrations in which ferricyanide does not react with amino adds other than cysteine.
The foregoing results have led to the following conclusions which, however, have not been definitely proven.
1. The definite reaction between denatured egg albumin in Duponol PC solution and dilute ferricyanide is a reaction with SH groups whereas the indefinite reactions with concentrated ferricyanide involve other groups.
2. The SH groups of denatured egg albumin in the absence of Duponol PC react with iodoacetamide and concentrated ferricyanide but they do not all react rapidly with dilute ferricyanide.
3. Duponol PC lowers the ferricyanide concentration at which the SH groups of denatured egg albumin react with ferricyanide. The SH groups of denatured egg albumin, however, are free and accessible even in the absence of Duponol PC.
PHYSICOCHEMICAL PROPERTIES OF THE PROTEOLYTIC ENZYME FROM THE LATEX OF THE MILKWEED, ASCLEPIAS SPECIOSA TORR. SOME COMPARISONS WITH OTHER PROTEASES
Authors: Winnick Theodore , Davis Alva R. , Greenberg David M. 
Published: May 2004

1. A study has been made of the properties of a hitherto unreported proteolytic enzyme from the latex of the milkweed, Asclepias speciosa. The new protease has been named asclepain by the authors.
2. The results of chemical, diffusion, and denaturation tests indicate that asclepain is a protein.
3. Like papain, asclepain dots milk and digests most proteins, particularly if they are dissolved in concentrated urea solution. Unlike papain, asclepain did not clot blood.
4. The activation and inhibition phenomena of asclepain resemble those of papain, and seem best explained on the assumption that free sulfhydryl in the enzyme is necessary for proteolytic activity. The sulfhydryl of asclepain appears more labile than that of papain.
5. The measurement of pH-activity curves of asclepain on casein, ovalbumin, hemoglobin, edestin, and ovovitellin showed no definite digestion maxima for most of the undenatured proteins, while in urea solution there were well defined maxima near pH 7.0. Native hemoglobin and ovovitellin were especially undigestible, while native casein was rapidly attacked.
6. Temperature-activity curves were determined for asclepain on hemoglobin, casein, and milk solutions. The optimum temperature was shown to increase with decreasing time of digestion.
SOME CHEMICAL ASPECTS OF THE POTASSIUM EFFECT
Authors: Osterhout W. J. V. 
Published: May 2004

The ability of Nitella to distinguish electrically between Na+ and K+ (potassium effect) appears to depend on several organic substances (or groups of substances). Of these RMK and RSK determine the mobility and partition coefficient (S) respectively of K+ while RMNa and RSNa do the same for Na+.
These substances can vary independently and this variation is susceptible to experimental control.
STUDIES ON PITUITARY LACTOGENIC HORMONE
Authors: Li Choh Hao , Lyons William R. , Evans Herbert M. 
Published: May 2004

The Tiselius technique of electrophoresis has been used to study the homogeneity and mobility of pituitary lactogenic hormone. The lactogenic preparation employed by us shows only one sharp band in schlieren photographs, indicating a high degree of homogeneity. From the determination of the mobility of the hormone at different hydrogen ion concentrations in acetate and phosphate buffer of ionic strength 0.055, the isoelectric point was found to be 5.70 and the
See PDF for Equation
value 4.5 x 10–5.
The difference in the mobility reported for White's crystalline preparation and that found with our high potency lactogenic preparation is discussed.
THE PIGMENT-PROTEIN COMPOUND IN PHOTOSYNTHETIC BACTERIA
Authors: French C. S. 
Published: May 2004

Absorption curves have been obtained in the spectral region of 450 to 900 mµ for the water soluble cell juice of four species of photosynthetic bacteria, Spirillum rubrum (strain S1), Rhodovibrio sp. (strain Gaffron), Phaeomonas sp. (strain Delft), and Streptococcus varians (strains C11 and orig.).
These curves all show maxima at 790 and 590 mµ due to bacteriochlorophyll, whose highest band, however, occurs at 875, 855, or 840 mµ depending on the species. The bacteria that appear red rather than brown have a band at 550 mµ due to a carotinoid pigment. An absolute absorption curve of bacteriophaeophytin has maxima at 530 and 750 mµ.
The extraction of cell juice by supersonic vibration does not change the position of the absorption bands or of the light absorbing capacity of the pigment.
REACTION TO VISUAL FLICKER IN THE NEWT TRITURUS
Authors: Crozier W. J. , Wolf Ernst 
Published: May 2004

The flicker response curve for the newt Triturus viridescens (water phase) has much the same quantitative structure as that found with various fresh-water teleosts at the same temperature (21.5°). The variability of critical intensity and of critical flash frequency likewise follows the same rules. The cone portion of the F - log I curve is much more widely spread, however. This, and the rather low maximum to which the rod curve rises, produce a considerable overlapping of the two parts additively fused.
In addition, and to an extent which differs in various individuals, there is apparent a slight departure from the probability integral form of the cone curve. Reasons are given for considering that this is possibly connected with the role of an additional (small) number of (perhaps temporary, or developmental) retinal elements in addition to the typical rods and cones.
THE ELECTRICAL CONDUCTANCE OF SUSPENSIONS OF ELLIPSOIDS AND ITS RELATION TO THE STUDY OF AVIAN ERYTHROCYTES
Authors: Velick Sidney , Gorin Manuel 
Published: May 2004

1. The theory of electrical conductance of colloidal suspensions has been extended to cover the case of ellipsoids with three axes different.
2. The results have been applied to suspensions of ellipsoidal erythrocytes of birds.
3. It has been shown that fluctuations in electrical resistance of suspensions of erythrocytes after stirring are due to streaming orientation of the cells.
4. The theory has been extended to cover four cases of orientation and tested experimentally in specially designed flow cells by electrical and optical methods.
5. Application of the flow method to the study of the shape of colloidal particles is discussed.
THE INFLUENCE OF SODIUM CHLORIDE AND TEMPERATURE ON THE ENDOGENOUS RESPIRATION OF B. CEREUS
Authors: Ingram M. 
Published: May 2004

Measurements were made of the rate of consumption of oxygen by suspensions of B. cereus, in sodium chloride solutions of concentration up to 1.8 M and over a range of pH from 6.0 to 7.5. It was found:
1. That the temperature coefficient was independent of the presence of sodium chloride in concentrations between 0.2 and 1.8 M, although the rate of respiration was lowered considerably under these conditions.
2. That in the presence of concentrations of sodium chloride less than 0.2 M, the rate of respiration was increased, and so was the temperature coefficient.
3. That small changes in the temperature coefficient occurred when the pH was changed. The temperature coefficient was higher the higher the rate of respiration.
These data may be more readily interpreted by the hypothesis that the temperature coefficient is controlled by some master reaction, than by that which supposes that the temperature coefficient is determined by protoplasmic viscosity.
NEW EXPERIMENTS ON ANOMALOUS OSMOSIS
Authors: Sollner Karl , Abrams Irving 
Published: May 2004

1. It is impossible to reproduce Loeb's observations on anomalous osmosis with membranes prepared from relatively pure brands of collodion, whereas positive effects can be obtained using collodion containing acidic impurities.
2. The inactive (purer) collodion membranes may be activated by oxidation with NaOBr solution.
3. Properly oxidized membranes give much greater anomalous osmotic effects than those described by Loeb.
ENZYMES IN ONTOGENESIS (ORTHOPTERA)
Authors: Allen Thomas Hunter , Bodine Joseph Hall 
Published: May 2004

1. Protyrosinase from the egg of the grasshopper, Melanoplus differentialis, can be activated by excess sodium oleate or Aerosol.
2. The 3:4 quinone products of the reaction of activated protyrosinase with tyramine or tyrosine will oxidize ascorbic acid to dehydroascorbic acid.
3. The velocity of this latter oxidation of ascorbic acid increases with the amount of tyramine or tyrosine.
4. The oxidation of ascorbic acid by the tyramine-tyrosinase reaction delays the time of appearance of a red color associated with an indole quinone intermediary product in the formation of melanin.
5. Protyrosinase, in itself, and in the presence of tyrosinase substrates does not bring about the oxidation of ascorbic acid.
6. A naturally occurring substrate in a preparation of protyrosinase, sufficient to cause the oxidation of ascorbic acid, can be removed by dialysis against a 0.9 per cent sodium chloride solution.
7. Dialysis against such a solution does not change the properties of protyrosinase; the inactive enzyme must still be activated before it will catalyze the oxidation of tyramine or tyrosine.
8. When the natural substrate, tyrosine, or tyramine is absent, activation of protyrosinase does not result in the oxidation of ascorbic acid.
THE EFFECT OF SWELLING ON THE RESPIRATION OF ERYTHROCYTES
Authors: Hunter F. R. , Banfield W. G. 
Published: May 2004

1. Oxygen consumption measurements made while a chicken erythrocyte swells show no increase over the control value.
2. There is no change in the rate of anaerobic glycolysis in beef erythrocytes when they swell.
3. The above statements are true whether the cells swell from a shrunken condition back to the normal volume, or swell from the normal to the hemolytic volume.
4. These data add a further test of the hypothesis that a relationship exists between the cell membrane and its respiratory activity.
ISOLATION, CRYSTALLIZATION, AND PROPERTIES OF PEPSIN INHIBITOR
Authors: Herriott Roger M. 
Published: May 2004

A method has been described for the isolation and crystallization of swine pepsin inhibitor from swine pepsinogen.
Solubility experiments and fractional recrystallization show no drift in specific activity.
The reversible combination of pepsin with the inhibitor was found to obey the mass law.
The inhibitor is quite specific, failing to act on other proteolytic and milk clotting enzymes. The inhibitor is destroyed by pepsin at pH 3.5.
Chemical and physical studies indicate that the inhibitor is a polypeptide of approximately 5,000 molecular weight with an isoelectric point at pH 3.7. It contains arginine, tyrosine, but no tryptophane and has basic groups in its structure.
THE SULFHYDRYL GROUPS OF EGG ALBUMIN
Authors: Anson M. L. 
Published: May 2004

1. 1 cc. of 0.001 M ferricyanide, tetrathionate, or p-chloromercuribenzoate is required to abolish the SH groups of 10 mg. of denatured egg albumin in guanidine hydrochloride or Duponol PC solution. Both the nitroprusside test and the ferricyanide reduction test are used to show that the SH groups have been abolished.
2. 1 cc. of 0.001 M ferrocyanide is formed when ferricyanide is added to 10 mg. of denatured egg albumin in neutral guanidine hydrochloride or urea solution. The amount of ferricyanide reduced to ferrocyanide by the SH groups of the denatured egg albumin is, within wide limits, independent of the ferricyanide concentration.
3. Ferricyanide and p-chloromercuribenzoate react more rapidly than tetrathionate with the SH groups of denatured egg albumin in both guanidine hydrochloride solution and in Duponol PC solution.
4. Cyanide inhibits the oxidation of the SH groups of denatured egg albumin by ferricyanide.
5. Some samples of guanidine hydrochloride contain impurities which bring about the abolition of SH groups of denatured egg albumin and so interfere with the SH titration and the nitroprusside test. This interference can be diminished by using especially purified guanidine hydrochloride, adding the titrating agent before the protein has been allowed to stand in guanidine hydrochloride solution, and carrying out the nitroprusside test in the presence of a small amount of cyanide.
6. The SH groups of egg albumin can be abolished by reaction of the native form of the protein with iodine. It is possible to oxidize all the SH groups with iodine without oxidizing many of the SH groups beyond the S-S stage and without converting many tyrosine groups into di-iodotyrosine groups.
7. p-chloromercuribenzoate combines with native egg albumin either not at all or much more loosely than it combines with the SH groups of denatured egg albumin or of cysteine.
8. The compound of mercuribenzoate and SH, like the compound of aldehyde and SH and like the SH in native egg albumin, does not give a nitroprusside test or reduce ferricyanide but does reduce iodine.
ENZYMES IN ONTOGENESIS (ORTHOPTERA)
Authors: Bodine Joseph Hall , Carlson Loren D. 
Published: May 2004

1. Proteins, when added to activators (sodium oleate. Aerosol) of protyrosinase, greatly decrease the degree of activation.
2. Certain proteins adsorbed on activator micelles are markedly affected by temperature and are rendered more sensitive by ultraviolet light.
3. Ideas are expressed as to the possible nature of activating and inhibiting phenomena especially as they relate to the enzyme tyrosinase.
A NEW METHOD FOR THE STUDY OF DIFFUSION OF BIOLOGICALLY ACTIVE MATERIAL
Authors: Bourdillon Jaques 
Published: May 2004

A simple diffusion apparatus has been described in which a layer of solution is allowed to diffuse upward into a layer of solvent. Accurate sampling is performed at various heights and the concentration of the samples is determined.
The method has been illustrated with a determination of the diffusion constant of crystalline catalase, which was found to be 3.1 x 10–7 cm.2/sec. at 4°C. The method should be especially suited to the study of biological substances endowed with specific activity and which cannot be obtained in pure solution.
THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR
Authors: Sollner Karl , Abrams Irving , Carr Charles W. 
Published: May 2004

1. The electrochemical behavior of membranes prepared from commercial collodion preparations varies widely, some preparations showing very high, other ones very low electrochemical efficiency ("activity").
2. The electrochemical activity of a collodion membrane depends entirely upon impurities of an acidic nature contained in the collodion used for casting the membrane.
3. The active acidic impurities are substantially due to partial oxidation which occurs in the manufacturing process. Sulfuric acid compounds; e.g., acid sulfuric acid esters play only a minor rôle, if any.
4. The electrochemical behavior of collodion membranes in solutions of strong electrolytes is decisively dependent upon the acidic groups built permanently into the collodion surfaces. Preferential ion adsorption plays only a minor, if any, rôle.