bluuebunny/crossref_metadata_2025 huggingface dataset:
STUDIES ON BLOOD COAGULATION
Authors: Eagle Harry
Published: May 2004

1. A method is described for the preparation and titration of prothrombin and thrombin.

2. Confirming the views of Morawitz, Howell (1916–17, 1925), and Bordet, thrombin cannot be regarded as an artificial by-product of coagulation (Wooldridge, Nolf (both quoted from Morawitz)). Calcium, a platelet factor, and a plasma factor (prothrombin) interact to form thrombin, and this then acts upon fibrinogen to form fibrin. The amount and rate of thrombin formation in the first reaction are independent of the presence or absence of fibrinogen. After a variable latent period, thrombin suddenly appears in large quantities, coincident with or immediately preceding the deposition of fibrin if fibrinogen is present.

3. The amount of thrombin formed in a mixture of prothrombin, Ca and platelets is independent of the platelet or Ca concentration, and depends primarily upon the amount of prothrombin used. The platelets (or cephalin) enormously accelerate the transformation of prothrombin to thrombin, and this acceleration seems to be their physiological rôle in the coagulation process.

4. Contrary to previous reports, platelets have not been demonstrated to contain significant quantities of prothrombin.

5. The available data do not allow any definite decision as to whether the platelet factor actually combines with prothrombin to form thrombin, or merely catalyzes the transformation. The very slow formation of thrombin in the complete absence of platelets may be due to dissolved traces of platelet material released during the physical manipulation of the plasma (centrifuging, Berkefeld filtration).

6. There was no evidence for a species-specific activity of platelets in the transformation of prothrombin to thrombin.
QUANTITATIVE STUDIES ON THE PHOTOLETHAL EFFECTS OF QUARTZ ULTRA-VIOLET RADIATION UPON PARAMECIUM
Authors: Giese A. C. , Leighton P. A.
Published: May 2004

Paramecia grown under controlled conditions were irradiated at known intensities of light of wave-lengths 2537, 2654, 2804, 3025, and 3130 A. The approximate absorption of the light by the Parmecia was found to be greatest and of the same order of magnitude at the three shortest wave-lengths, considerably less at 3025, and least at 3130 A.

Paramecia did not die when irradiated with high dosages of intense light of wave-length 3130 A. At the other wave-lengths 50 per cent vesiculation occurred when between 1012 and 1013 quanta had been absorbed by a Paramecium. This would indicate that a very large number of molecules in a Paramecium are affected before vesiculation occurs.
THE RELATION BETWEEN CHLOROPHYLL CONTENT AND RATE OF PHOTOSYNTHESIS
Authors: Fleischer Walter E.
Published: May 2004

1. Data are presented which support the conclusion of Emerson (1929) that the rate of photosynthesis is proportional to the chlorophyll content when the latter is varied by varying the iron supply. These data give a straight line passing through the origin, which is not true of Emerson's results.

2. Similar data are presented which show that a similar relation exists when nitrogen controls the chlorophyll content.

3. Evidence is given which indicates that magnesium plays a part in the process of photosynthesis in addition to its effect upon the chlorophyll content.
ON THE GEOTROPIC ORIENTATION OF HELIX
Authors: Crozier W. J.
Published: May 2004

The snail Helix nemoralis in negatively geotropic creeping orients upward upon an inclined surface until the angle of the path of progression (θ) is related to the tilt of the surface (α) as (Δ sin θ) (Δ sin α) = – const.; θ is very nearly a rectilinear function of log sin α. The precision of orientation (P.E.θ) declines in proportion to increasing sin α, P.E.θ/θ in proportion to θ. These facts are comprehensible only in terms of the view that the limitation of orientation is controlled by the sensorial equivalence of impressed tensions in the anterior musculature.
PROTECTIVE ACTION IN IRRADIATION OF AMYLASE SOLUTIONS WITH ULTRAVIOLET LIGHT
Authors: Thompson William R. , Tennant Robert
Published: May 2004

Evidence has been presented which indicates that the protective action of dogs' sera in irradiation of pancreatin solutions with ultraviolet light is the result of a competitive absorption (screening action). A similar effect is found in simple pancreatin solutions for which we may account (at least to a first approximation) on the basis of assumed homogeneous absorption by a strong competitor in the solution for the radiations having inactivating power. These observations are of interest in connection with the theory of what has been called negative catalysis, especially in view of the marked effects of small quantities of the protecting substances.
MECHANICAL RESTORATION OF IRRITABILITY AND OF THE POTASSIUM EFFECT
Authors: Hill S. E. , Osterhout W. J. V.
Published: May 2004

Treatment of Nitella with distilled water apparently removes from the cell something which is responsible for the normal irritability and the potassium effect, (i.e. the large P.D. between a spot in contact with 0.01 M KCl and one in contact with 0.01 M NaCl). Presumably this substance (called R) is partially removed from the protoplasm by the distilled water. When this has happened a pinch which forces sap out into the protoplasm can restore its normal behavior.

The treatment with distilled water which removes the potassium effect from the outer protoplasmic surface does not seem to affect the inner protoplasmic surface in the same way since the latter retains the outwardly directed potential which is apparently due to the potassium in the sap. But the inner surface appears to be affected in such fashion as to prevent the increase in its permeability which is necessary for the production of an action current. The pinch restores its normal behavior, presumably by forcing R from the sap into the protoplasm.
ELECTROPHORESIS OF STEROLS
Authors: Moyer Laurence S.
Published: May 2004

The electrophoretic behavior of powdered ergosterol crystals is identical with that previously found for cholesterol within the limits of experimental error. Evidence for an adsorption hypothesis is presented to explain this phenomenon.
ON THE RELATION OF DIRECT CURRENTS TO CONDENSER DISCHARGES AS STIMULI
Authors: Blair H. A.
Published: May 2004

Data on the electrical stimulation of sciatic-gastrocnemius preparations of the frog by both direct currents and condenser discharges at the same time are discussed in relation to the validity of the differential equation

See PDF for Equation

where p is the local excitatory process, V the stimulating current or voltage, and K and k are constants. It is concluded that the constant k is the same whether it is derived from the data of the one stimulus or the other when the same fibres are being stimulated.
THE ELECTRIC IMPEDANCE OF HEMOLYZED SUSPENSIONS OF MAMMALIAN ERYTHROCYTES
Authors: Fricke Hugo , Curtis Howard J.
Published: May 2004

This paper is concerned with the changes in the electric surface capacity and surface resistivity of the membrane surrounding the mammalian red corpuscle, as a result of various types of hemolysis. In the case of hemolysis with water, the cells swell with no apparent change in the electric properties of the membrane. They then hemolyze, but the membrane persists, although showing evidence of injury, as indicated by a change in the frequency dependence of its capacity and resistivity at low frequencies. The fact that a change of the frequency dependence takes place shows that the injury cannot be due merely to a rupture in the membrane, but must be due to changes in the properties (increased permeability) of the membrane as a whole.

With chemical lysins (saponin, complement and amboceptor, digitonin, sodium taurocholate) a similar type of injury to the membranes of a certain number of the corpuscles takes place, to an increasing extent as the concentration of lysin is increased. The rest of the corpuscles become completely permeable to the electric current, and as the amount of lysin is increased, this number of completely permeable corpuscles increases until all are affected. This change, presumably associated with a disintegration of the corpuscle membrane, is referred to as stromatolysis, and the method gives a quantitative means of determining percentage stromatolysis.

For lysis by freezing and thawing, the results obtained indicate this type of lysis to be different from that of the others studied.
THE EFFECT OF LIGHT INTENSITY, AREA, AND FLICKER FREQUENCY ON THE VISUAL REACTIONS OF THE HONEY BEE
Authors: Wolf Ernst , Zerrahn-Wolf Gertrud
Published: May 2004

1. For the phototropic reaction of bees, the stimulating effects of two illuminated fields differing in intensity and area become equal when the product of area and intensity is the same for both fields.

2. The effect of two areas differing in size and flicker frequency is the same for the bee, when the product of area and flicker frequency is equal for both fields.

3. If two patterns of the same character but varying in size and coarseness are presented to bees for free choice, a 1:1 ratio of choices is obtained when both patterns stimulate equal numbers of retinal elements alternately by transition from one state of excitation to another.
VITAMIN A IN EYE TISSUES
Authors: Wald George
Published: May 2004

1. Vitamin A has been found in the retinas and the combined pigment epithelia and choroid layers of frogs, pigs, sheep, and cattle. The vitamin was identified by (a) its specific absorption at 328 mµ; (b) the blue color yielded with antimony trichloride, associated with an absorption band at about 620 mµ; (c) anti-xerophthalmic and growth-promoting activity; and (d) quantitative relationships among the results of these three types of observation.

2. The mammalian retinas contain about 22γ, the frog retinas about 400γ, and the frog pigmented layers almost 2 mg. of vitamin A per gram of dry tissue.

3. With the possible exception of hepaxanthin, no other carotenoids were found in the mammalian tissues.
THE RESPONSE OF SINGLE VISUAL SENSE CELLS TO LIGHTS OF DIFFERENT WAVE LENGTHS
Authors: Graham C. H. , Hartline H. K.
Published: May 2004

The effect of various wave lengths of visible light in the stimulation of single visual sense cells has been studied by means of the single fiber preparation from the eye of Limulus. Oscillographic records were made of the impulse discharge in a single optic nerve fiber in response to stimulation of the attached sense cell by lights of different wave lengths. Wratten monochromatic filters supplied the means for obtaining the different spectral lights; the total intensity supplied to the eye being determined by a thermopile and galvanometer.

With lights of approximately equal energy content the strongest response occurs to the green region of the spectrum. The response, however, does not vary qualitatively with wave length. By the proper adjustment of intensity, responses can be obtained which are identical, impulse for impulse, for all the spectral lights used. Moreover the ratios of the intensities for the various wave lengths necessary to produce a constant response do not vary with the intensity level of the stimulating lights; there is no Purkinje effect. The single visual sense cell can gauge brightness but cannot distinguish wave length.

The reciprocals of the intensities necessary to produce a constant response when plotted against wave length give the visibility curve for the single sense cell. This curve is symmetrical about a maximum at λ520mµ, falling off to low values in the red and violet. It closely resembles the visibility curve for human rod vision.

Bundles from the optic nerve containing several active fibers whose impulses can be distinguished by differences in form and magnitude or whose attached sense cells can be located and illuminated independently were used to determine whether there is any differential sensitivity among sense cells in the same eye for different regions of the spectrum. Such a differential sensitivity has been found to exist in the eye of Limulus and may be considered a peripheral mechanism of color vision.
CHEMICAL RESTORATION IN NITELLA
Authors: Osterhout W. J. V.
Published: May 2004

The potassium effect in Nitella (the high P.D. observed in leading off from a spot in contact with 0.01 M KCl to one in contact with 0.01 M NaCl) and the irritability can be removed by placing cells in distilled water for 2 or 3 days. They can be restored by NH3 or by NH4Cl. The potassium effect can also be restored by tetraethyl ammonium chloride (no tests were made of its ability to restore irritability).
THE COMBINATION OF DIVALENT MANGANESE WITH CERTAIN PROTEINS, AMINO ACIDS, AND RELATED COMPOUNDS
Authors: Main Raymond K. , Schmidt Carl L. A.
Published: May 2004

1. A study of the mode of combination which takes place between certain amino acids, proteins, various carboxylic acids, and certain sulfonic acids and manganous ions to form complexes is reported.

2. Three criteria for complex formation were used: (a) the equilibrium between the substance under test and manganous ions dissolved in aqueous buffered solution and isonitrosoacetophenone dissolved in chloroform; (b) the electrophoretic migration of manganese in the presence of the test substance with varying pH; and (c) anomalous titration.

3. The following classes of substances were found to possess the necessary groupings to form manganese complexes: hydroxy-monocarboxylic acids (lactic, gluconic), dicarboxylic acids (oxalic, malonic), hydroxy-, di- and tricarboxylic acids (citric, tartaric), dicarboxylic amino acids (aspartic, glutamic), certain inorganic acids (phosphoric, sulfuric), certain phosphoric acid-containing compounds (nucleic, glycerophosphoric), certain aromatic enol sulfonic acids (phenolsulfonic, catecholsulfonic), and certain proteins (casein, edestin, gelatin).

4. A correlation between the amount of manganese bound by the several proteins and the free carboxyl and phosphoric acid groups has been made.

5. An explanation based on the residual charge of certain atoms is advanced for the manner in which divalent manganese may be united by the compounds studied.
INCREASED PERMEABILITY TO WATER OF AGING UNFERTILIZED EGGS (ARBACIA PUNCTULATA)
Authors: Goldforb A. J.
Published: May 2004

1. Unfertilized Arbacia eggs, subjected to 50, 60, or 80 per cent sea water, at the same temperature, pH, and duration, swelled progressively faster with age. Swelling increased 12.2 to 39.6 per cent.

2. Permeability to water was calculated by the method of Lucké and McCutcheon. For freshly shed eggs from nine different females, permeability varied from 0.078 to 0.124, or 59 per cent. This variation was not due to differences in age nor to physiologic condition but was correlated with size of eggs.

3. About twenty eggs were tested each age to 60 hours after shedding. The permeability rate increased with age in all nine experiments.

4. The total increase ranged from 30 to 69 per cent.

5. The increase was slow but constant or almost constant during early and intermediate ages.

6. The increase began at earliest ages.

7. An increase may not be demonstrable for any short interval but is readily demonstrable for longer intervals (6 or more hours), or, from the entire curve.

8. Permeability increased faster at late ages. For special factors during late ages see text.

9. Injury by experimental procedure was not induced until ca. the 24th hour. Injury by aging was not detectable during the first 6 to 9 hours. It increased progressively between 10 and 24 hours, and very rapidly thereafter. Permeability increased at approximately the same rate during early and intermediate ages. Permeability therefore was not correlated with degree of injury.

10. The troublesome factor in the permeability equation was initial size, or Vo. Several methods were used to obtain this Vo, viz. (a) extrapolations approximating known cyclical change in size, (b) extrapolations approximating control sizes, (c) constant or average of all Vo's, (d) maximum Vo approximating control Vo's. Recalculation with these different Vo's gave approximately the same permeabilities.

11. The increase in permeability with age was substantially the same whether "approved," or other possible rates or average rates or range of rates be used as criteria of change.

12. When the data were recalculated by integrating the equation of Northrop, the increases in permeability with age were essentially the same as the increases calculated by the graphic method of Lucké.
THE ACCUMULATION OF ELECTROLYTES
Authors: Osterhout W. J. V. , Kamerling S. E.
Published: May 2004

Models are described in which KCl enters until its chemical potential becomes much greater inside than outside. The energy needed to accomplish this comes from the chemical reactions occurring in the system and the continual supply of certain materials. An important factor is the maintenance of a lower pH value inside by means of CO2. This may be analogous to what happens in some living cells.

The concentration of K+ becomes higher inside, as happens in many living cells, but the concentration of Cl- does not and in this respect the model differs from many living cells. As in Valonia, potassium tends to go out as KCl when the ionic activity product (K)(Cl) is greater inside but at the same time it tends to enter as KOH since the activity product (K)(OH) is greater outside. The net result is entrance of potassium presumably because the latter process is the more rapid.
THE THICKNESS OF THE WALL OF THE RED BLOOD CORPUSCLE
Authors: Danielli James Frederic
Published: May 2004

Fricke's assumption, that the dielectric constant of the erythrocyte wall is 3, is discussed. The assumption is approximately correct in the case of a solid layer of any thickness, and in the case of a liquid layer of not more than bimolecular thickness. For liquid layers of greater thickness the dielectric constant may be several times greater than 3. Calculated values based on experimental determinations are given of the dielectric constants of the polar groups of unimolecular films.
ELECTROPHORESIS OF STEROLS
Authors: Moyer Laurence S.
Published: May 2004

1. No significant differences were noted between the electrophoretic mobilities of unground cholesterol crystallized from alcohol, acetone, or the melted state.

2. On grinding with ice at –10°C. the mobility drops to less than half (at pH 5.8) that observed in the unground state. This equilibrium condition is reached after 50 minutes grinding. Cholesterol crystals from alcohol or acetone behave identically throughout the course of this change.

3. When cholesterol crystals which have been ground with ice are dried in vacuo at room temperature they revert to the mobility of unground cholesterol. The cause of this phenomenon is discussed.

4. Both ground and unground cholesterol have an isoelectric point near pH 3.0, even after crystallization from the melted state.
THE DENATURATION OF EGG ALBUMIN BY ULTRA-VIOLET RADIATION
Authors: Clark Janet Howell
Published: May 2004

The coagulation of isoelectric egg albumin solutions, on exposure to ultraviolet radiation, involves three distinct processes, (1) the light denaturation of the albumin molecule, (2) a reaction between the light denatured molecule and water which may be similar to heat denaturation but occurs at a lower temperature, and (3), the flocculation of the denatured molecules to form a coagulum. The light denaturation is unimolecular, independent of temperature, and occurs over a wide pH range. The reaction between the light denatured molecule and water has a temperature coefficient of 10+ and occurs rapidly at 40°C., a temperature at which heat denaturation is inappreciable.
ELECTROKINETICS
Authors: Moyer Laurence S. , Bull Henry B.
Published: May 2004

1. The question of the critical pore diameter for streaming potential is discussed.

2. The surface charge is calculated for cellulose in contact with solutions of K3PO4, K2CO3, K2SO4, KCl, and ThCl4.

3. The surface charge of cellulose in contact with a solution of 2 x 10–4 N NaCl is calculated as a function of temperature and is found to show a sharp break at 39°. This is interpreted in terms of the change of the specific heat of water.

4. A marked ion antagonism is found in NaCl:KCl, KCl:MgCl2, NaCl:MgCl2, NaCl:CaCl2, KCl:CaCl2, CaCl2:MgCl2 mixtures when the surface charge is calculated as a function of concentration.
THE ALLEGED EFFECT OF ELECTRICAL STIMULATION ON THE METABOLISM OF RED CELL SUSPENSIONS
Authors: Ponder Eric , Macleod John
Published: May 2004

The apparent increase in the rate of O2 consumption described when an alternating current, or induction coil current, is passed through a red cell suspension (in a buffered NaCl solution) is not a metabolic effect in any sense of the word. The passage of the current results in a permanent volume decrease in the system, and it is this which has been erroneously interpreted as an "increase in the rate of O2 consumption." Its magnitude is about 1 part in 1000. The utilization of O2 is not involved at all, and the same effect is obtained, on a somewhat smaller scale, when the current is passed through a solution of NaCl or of the other halogen salts. The effects occur only with shiny platinum electrodes, and disappear entirely when the electrodes are platinized. Passage of the current through serum, on the other hand, results in a permanent increase in the volume of the system, this effect also disappearing on platinization of the electrodes. The effects are apparently related to obscure electrode phenomena.
ACETYLATION OF TYROSINE IN PEPSIN
Authors: Herriott Roger M.
Published: May 2004

Crystalline 60 per cent active acetyl pepsin has 7 acetyl groups per mol of pepsin, 3 of which are readily hydrolyzed in acid at pH 0.0 or in weak alkali at pH 10.0.

The tyrosine-tryptophane content of this acetylated pepsin, measured colorimetrically, is less than pepsin by three tyrosine equivalents.

Hydrolysis at pH 0.0 or pH 10.0 of the 3 acetyl groups results in a concomitant increase in the number of tyrosine equivalents. In the pH 0.0 hydrolysis experiment there is also a simultaneous increase in specific activity.

The phenol group of glycyl tyrosine is acetylated by ketene under the conditions used in the acetylation of pepsin and the effect of pH on the rate of acetylation is similar in the two cases.

It is concluded that the acetyl groups in the 60 per cent active acetyl pepsin, which are responsible for the decrease in specific enzymatic activity, are 3 in number and are attached to 3 tyrosine phenol groups of the pepsin molecule.
STUDIES ON BIOLUMINESCENCE
Authors: Anderson Rubert S.
Published: May 2004

Some solubility, oxidation, reduction, and compound-forming characteristics of extracts of Cypridina luciferin have been presented.

A method of purification has been described which increased the amount of luciferin per unit of dry weight, as measured by the total light emitted, to about two thousand times that in the dry starting material. The best yields were from 50 to 65 per cent.
A FORMULATION OF THE SEROLOGICAL FLOCCULATION RATE IN THE REGION OF CONSIDERABLE ANTIBODY EXCESS
Authors: Hooker Sanford B. , Boyd William C.
Published: May 2004

Attention is called to a phase of antigen-antibody reactions in which the times of flocculation are linearly proportional to the dilutions of antigen (region of considerable antibody excess), and a theoretical interpretation is offered.
THE SOLUBILITIES OF THE l-DIHALOGENATED TYROSINES IN ETHANOL-WATER MIXTURES AND CERTAIN RELATED DATA
Authors: Winner Philip S. , Schmidt Carl L. A.
Published: May 2004

1. The solubilities of l-tyrosine, dichloro-l-tyrosine (hydrated), dibromo-l-tyrosine (anhydrous), and diiodo-l-tyrosine in ethanol-water mixtures at 25° have been determined.

2. It was found that the solubilities of the dihalogenated substitution products of l-tyrosine are increased by addition of ethanol up to a certain concentration. Further addition of ethanol leads to a decrease in solubility. The solubility of l-tyrosine is decreased by addition of ethanol.

3. Dichloro-l-tyrosine (hydrated) was found to change to the anhydrous form when allowed to stand in the presence of ethanol.

4. The apparent heat of solution of diiodo-l-tyrosine in an ethanol-water mixture has been determined.

5. The solubility of dl-thyroxine at 30° has been determined in urea solution, ethanol, dioxan, ethylene glycol, and propylene glycol.
THE FORMATION OF MILK SUGAR
Authors: Weinbach Ancel P.
Published: May 2004

1. The mammary glands of rats in the height of lactation were frozen in situ, removed, and dried in the vacuum in the frozen state.

2. The dried gland, added to pig serum, pig serum plus glucose, pig serum plus galactose, and pig serum plus lactose, then incubated at 37.5°C., yielded a synthesis of non-fermentable, reducing material.

3. The dried gland added to glucose solution alone and incubated at 37.5°C. yielded a synthesis of a non-fermentable reducing disaccharide, having a reaction velocity of reduction resembling that of pure lactose.

4. There is a "short time" storage of some forms of lactose precursor in the active mammary gland. This precursor is non-reducing but becomes available and reducing when the gland is placed in a solution containing glucose.
IONIC TRANSFERENCE NUMBERS IN CELLOPHANE MEMBRANES
Authors: Teorell Torsten
Published: May 2004

The "apparent" cation transference number within cellophane is determined for HCl, KCl, NH4Cl, NaCl, and LiCl.

The method consists in measuring the E.M.F. in a concentration chain employing Ag:AgCl electrodes or calomel electrodes and calculating from formulas derived for cases of simple, unconstrained diffusion.

The transference numbers and the cation mobilities relative to the chloride ion were found to be higher in the cellophane (relative cation mobilities increased about 40 per cent).

The effect of the membrane is discussed. It is emphasized that with the introduction of a membrane as a liquid junction new factors are introduced, which are not considered in the formulas ordinarily used. Such factors may be activity changes due to dimensional or other reasons and particularly electrical effects exhibited by the membrane upon the ionic diffusion. Accordingly the transference number, as determined, may lack well defined physical significance.
INTERMITTENT STIMULATION BY LIGHT
Authors: Hecht Selig , Shlaer Simon
Published: May 2004

1. An optical system is described which furnishes large flickering fields whose brightness, even when reduced with monochromatic filters, is capable of covering the complete range of the relation between critical frequency and intensity.

2. For a centrally located test field of 19° diameter, with light from different parts of the spectrum, the data divide into a low intensity section identified with rod function, and a high intensity section identified with cone function. The transition between the two sections is marked by an inflection point which is sharp, except for 450 and 490 mµ where, though clearly present, it is somewhat rounded.

3. The intensity range covered by the flicker function is smallest in the red, and increases steadily as the wave-length decreases. The increase is due entirely to the extent of the low intensity, rod section which is smallest (non-existent for S. S.) in the red and largest in the violet. The high intensity cone portion for all colors is in the same position on the intensity axis, and the only effect of decreasing wave-length is to shift the rod section to lower intensities without changing its shape.

4. The measurements are faithfully described by two similar equations, one for the rods and one for the cones, both equations being derived from the general stationary state equation already used for various visual functions.
INTERMITTENT STIMULATION BY LIGHT
Authors: Hecht Selig , Smith Emil L.
Published: May 2004

1. In the retina, central areas whose diameter is less than 2° possess only cones, while larger areas have rods and cones. In conformity with this, the relation of critical fusion frequency to intensity is a single function for centrally fixated areas below 2°, and a double function for similarly fixated, larger areas. The two sections of such data are easily identified with rod activity at low intensities and with cone activity at high intensities.

2. The curves describing the rod data are the same for all areas, differing only in the values of the associated dimensional constants which control the location of the curves on the coordinate axes. Similarly, the curves for the cone data are the same for all areas; the tendency for an increase in maximal frequency with area is the expression merely of the value of a constant which determines the position of the data on the frequency axis. Area, therefore, does not influence the fundamental nature of the flicker relation through each receptor system, but merely alters the extraneous constants of the relation.

3. The curves which describe the measurements are represented by two equations, one for rods and one for cones; both equations are derived from the stationary state descriptive of the initial event in the photoreceptor process.
ANALYSIS OF THE GEOTROPIC ORIENTATION OF YOUNG RATS. X
Authors: Crozier W. J. , Pincus G.
Published: May 2004

The inheritance of elements of geotropic performance in lines of rats (A and B) has been investigated by examining the orientation of young offspring produced in matings of F1(A x B) with A: Previous studies had shown that the three recognizable groups of receptor elements concerned in geotropic orientation in each of these lines appeared to be inherited in such a way that B groups were dominant with respect to A groups, although this was to a minor extent complicated by influences affecting the variation of orientation as well as the exact form of the curve relating orientation angle (θ) to slope of surface. In the backcross F1 x A, therefore, at least eight different types of curves were to be expected. These are in fact identifiable among the forty-one individuals carefully studied. Their classification is concordant with the behavior of the respective indices of variation of θ, for which an interpretation has been provided. The basic result is, therefore, that the three receptor groups of excitation units are inherited independently, and alternatively as regards the members of a homologous pair, and that rather simple dominance relations obtain between homologous groups from the two races, namely that a B effect is dominant over the homologous A effect. This interpretation has been tested in various ways, and is in principle completely consistent with the results of a similar experiment involving races A and K.
STATISTICAL EVALUATION OF SIEVE CONSTANTS IN ULTRAFILTRATION
Authors: Ferry John D.
Published: May 2004

The partial retention of the disperse phase in the ultrafiltration of a monodisperse system through an isoporous filter is interpreted on a statistical basis, and a simple expression for the sieve constant is evaluated in terms of the calibrated membrane porosity and the particle size. Curves calculated from this expression are in reasonable agreement with experimental data for the ultrafiltration of serum albumin, hemocyanin (Helix), and foot-and-mouth disease virus.
INTENSITY DISCRIMINATION IN THE HUMAN EYE
Authors: Steinhardt Jacinto
Published: May 2004

New measurements of the brightness difference sensibility of the eye corroborate the data of previous workers which show that ΔI/I decreases as I increases. Contrary to previous report, ΔI/I does not normally increase again at high intensities, but instead decreases steadily, approaching a finite limiting value, which depends on the area of the test-field and on the brightness of the surrounding field.

On a logarithmic plot, the data of ΔI/I against I for test-fields below 2° are continuous, whereas those for test-fields above 2° show a sharp discontinuity in the region of intensity in which ΔI/I decreases rapidly. This discontinuity is shown to divide the data into predominantly rod function at low intensities, and predominantly cone function at high intensities. Fields below 2° give higher values of ΔI/I at all intensities, when compared with larger fields. Fields greater than one or two degrees differ from one another principally on the low intensity side of the break. Changes in area above this limit are therefore mainly effective by changing the number of rods concerned. This is confirmed by experiments controlling the relative numbers of rods and cones with lights of different wavelength and with different retinal locations.

At high intensities ΔI/I is extremely sensitive to changes in brightness of surrounding visual fields, except for large test-fields which effectually furnish their own surrounds. This sensitivity is especially marked for fields of less than half a degree in diameter. Although the effect is most conspicuous for high intensities, the surround brightness seems to affect the relation between variables as a whole, except in very small fields where absence of a surround of adequate brightness results in the distortion of the theoretical relation otherwise found.

The theoretical relationship for intensity discrimination derived by Hecht is shown to fit practically all of the data. Changes in experimental variables such as retinal image area, wavelength, fixation, and criterion may be described as affecting the numerical quantities of this relationship.
A DESEEDED AVENA TEST METHOD FOR SMALL AMOUNTS OF AUXIN AND AUXIN PRECURSORS
Authors: Skoog Folke
Published: May 2004

The main results presented in this article may be summarized as follows:

1. A test method with deseeded Avena seedlings for small concentrations of auxin and precursors of auxin has been described.

2. This method makes possible quantitative determinations of about ten times as low concentrations of hormone as can be obtained with the standard method, (a) Through an increase in the time of the test, so that nearly all the hormone applied can be utilized. (b) Through an increase in sensitivity of deseeded plants to unilaterally applied small concentrations of hormone.

3. The effect of deseeding in relation to curvature growth is primarily the prevention of auxin regeneration through the removal of the material for auxin synthesis, and in addition the prevention of physiological aging.

4. The mechanism of auxin synthesis in the tip of the coleoptile and the mechanism of auxin regeneration in the new physiological tip have been shown to be identical.

5. The application of the deseeded method is illustrated by determinations of auxin in primary leaves and coleoptile sections of Avena seedlings.

6. The deseeded method has been used as a test method for precursors of auxin obtainable from the coleoptile and from other sources. The method further makes possible a distinction between auxins and these substances which may become activated by the plant.

7. Evidence for the existence of a precursor of auxin in the plant is given (a) indirectly by determinations of the decrease in auxin synthesis in deseeded plants. (b) Directly by its isolation from the plant.

8. Precursors of hetero-auxin are demonstrated; their chemical nature and activation are briefly considered.
TEMPERATURE AND CRITICAL ILLUMINATION FOR REACTION TO FLICKERING LIGHT
Authors: Crozier W. J. , Wolf Ernst , Zerrahn-Wolf Gertrud
Published: May 2004

The curve of mean critical illumination (Im) for response to flicker as a function of flicker frequency (F) for the larvae of the dragonfly Anax junius is progressively shifted toward higher intensities the lower the temperature. The maximum flicker frequency (one half the cycle time of light and no light) and the maximum intensity with which it is associated are very little if at all affected by change of temperature.

These facts are in agreement with the requirements of the conception that recognition of critical illumination for reaction to flicker involves and depends upon a kind of intensity discrimination, namely between the effects of flashes and the after effects of these flashes during the intervals of no light. The shift of the F-Im curve with change of temperature is quite inconsistent with the stationary state conception of the determination of the shape of the curve.

The dispersion (P.E.II1) of the measurements of I1 is directly proportional to Im, but the factor of proportionality is less at high and at low temperature than at an intermediate temperature; the scatter of the values of P.E.II1 is also a function of the temperature. These facts can also be shown to be concordant with the intensity discrimination basis for marginal recognition of flicker.
CONCERNING CRITICAL PERIODS IN THE LIFE OF ADULT DROSOPHILA
Authors: Crozier W. J. , Enzmann E. V.
Published: May 2004

Periodic accelerations in the decreasing resistance of adult Drosophila (pure line) to the penetration of alcohol vapor are specifically paralleled by changes in the rate of accumulation of deaths in a life duration experiment with the same line. The necessary interpretation is that there occur under constant conditions periodic fluctuations in the speed of general metabolic events, marking the limits of what may be termed metabolic instars.
SPECTROSCOPY OF CATALASE
Authors: Stern Kurt G.
Published: May 2004

Catalase is resistant to oxidizing agents; e.g., ferricyanide. It is also resistant to reducing agents; e.g., catalytically activated hydrogen, hydrosulfite, ferrotartrate, cysteine. The hemin group of the enzyme will combine with cyanide, sulfides, nitric oxide, fluoride. It will not combine with carbon monoxide. Catalase is therefore a ferric complex. The stability of the ferric iron in the enzyme toward reducing agents is not due to the structure of the porphyrin with which it is combined. This porphyrin is the protoporphyrin of the blood pigment. In combination with globin (methemoglobin) the ferric iron is readily reduced by the same reagents which have no effect on catalase. The stability of the ferric iron in the enzyme is therefore due to the protein component. It may be that the type of hematin-protein linkage in catalase is the reason for this phenomenon. The suggestion of Bersin (31), that sulfur may participate in this linkage, is interesting but, as yet, has no experimental basis.

Hydrazine or pyridine and hydrosulfite convert catalase into hemochromogens containing ferrous iron. But in these hemochromogens the hematin is no longer attached to the protein. This has been replaced by the nitrogenous bases hydrazine and pyridine. Both hemochromogens combine reversibly with carbon monoxide. Photo-dissociation has only been demonstrated in the case of the pyridine hemochromogen.

The positions of the absorption bands of catalase and its derivatives are listed in Table II.

The main absorption band (Soret's band) of hemin complexes with nitrogenous substances (nitrogen bases, proteins) is situated at the border between the visible and the ultraviolet region of the spectrum. It has now been found that the spectrum of purified liver catalase has a well defined maximum of high extinction in this range, at 409 mµ. This is further evidence for the hemin nature of the enzyme.
THE QUANTUM YIELD OF HYDROGEN AND CARBON DIOXIDE ASSIMILATION IN PURPLE BACTERIA
Authors: French C. S.
Published: May 2004

1. The effect of H2 tension, CO2 tension, pH, time, light intensity, density of suspension, salt content of the medium, and certain spectral regions on the rate of photoassimilation of H2 and CO2 by Streptococcus varians has been studied.

2. The method of making light absorption measurements with thin suspensions of bacteria is described.

3. A light source, optical system, and filter for isolating 852 mµ with 894 mµ in sufficient intensity for photochemical work and an improved design of thermostat are given.

4. The photoassimilation of 2H2 with 1CO2 apparently involves little over all energy change but nevertheless requires 4 quanta.
THE KINETICS OF PENETRATION
Authors: Jacques A. G.
Published: May 2004

When 0.1 M NaI is added to the sea water surrounding Valonia iodide appears in the sap, presumably entering as NaI, KI, and HI. As the rate of entrance is not affected by changes in the external pH we conclude that the rate of entrance of HI is negligible in comparison with that of NaI, whose concentration is about 107 times that of HI (the entrance of KI may be neglected for reasons stated).

This is in marked contrast with the behavior of sulfide which enters chiefly as H2S. It would seem that permeability to H2S is enormously greater than to Na2S. Similar considerations apply to CO2. In this respect the situation differs greatly from that found with iodide.

NaI enters because its activity is greater outside than inside so that no energy need be supplied by the cell.

The rate of entrance (i.e. the amount of iodide entering the sap in a given time) is proportional to the external concentration of iodide, or to the external product [N+]o [I-lo, after a certain external concentration of iodide has been reached. At lower concentrations the rate is relatively rapid. The reasons for this are discussed.

The rate of passage of NaI through protoplasm is about a million times slower than through water. As the protoplasm is mostly water we may suppose that the delay is due chiefly to the non-aqueous protoplasmic surface layers. It would seem that these must be more than one molecule thick to bring this about.

There is no great difference between the rate of entrance in the dark and in the light.
THE APPARENT DISTORTION OF BRIEF RECTANGULAR ELECTRICAL STIMULI IN NERVE
Authors: Blair H. A.
Published: May 2004

If it is assumed that the kinetics of the process of excitation in nerve is given by dp/dt = KI – kp, I being the actual exciting component of the current, p the state of excitation, and K and k constants, it is necessary to postulate that on application of a rectangular stimulus of voltage, V, the current, I, undergoes a transient exponential variation, usually a decrease, in order that the integral of the differential equation (above) may fit the strength-duration data in V and t. This hypothesis is substantiated by data by Sakamoto on single fibers of the sciatic nerve of the frog. The time constant of the postulated current transient is of the order of 10–4 sec. for single fibers and of the order of 10–5 sec. or less in the sciatic nerve trunk. The latter value is about the same as that found by Cole in the same tissue by purely physical measurements. Some criticisms by Rushton (1934) are discussed.
A PHASE RULE STUDY OF THE PROTEINS OF BLOOD SERUM: THE EFFECT OF CHANGES IN CERTAIN VARIABLES
Authors: Jameson Eloise
Published: May 2004

Changes were studied in the standard solubility curve of fresh serum proteins by alterations in pH, temperature, concentration of protein, and nature of the salt used for precipitation.

The principal factor affecting the precipitation of protein fractions was a change in temperature. In order to investigate the proteins in their original states low temperatures are necessary.

Protein fraction A is altered by a change in pH and with the use of (NH4)2SO4 as a precipitant, fraction B by a change in pH and temperature, and use of (NH4)2SO4, C by a change in temperature and concentration of the protein, and D by a change in temperature and pH.

The solubility of D is independent of the amount of protein in solution in high concentrations of salt.
CRITICAL ILLUMINATION AND FLICKER FREQUENCY IN RELATED FISHES
Authors: Crozier W. J. , Wolf E. , Zerrahn-Wolf Gertrud
Published: May 2004

Flicker response curves have been obtained at 21.5°C. for three genera of fresh water teleosts: Enneacanthus (sunfish), Xiphophorus (swordtail), Platypoecilius (Platy), by the determination of mean critical intensities for response at fixed flicker frequencies, and for a certain homogeneous group of backcross hybrids of swordtail x Platy (Black Helleri).

The curves exhibit marked differences in form and proportions. The same type of analysis is applicable to each, however. A low intensity rod-governed section has added to it a more extensive cone portion. Each part is accurately described by the equation

F = Fmax./(1 + e-p log-p logI/Ii),

where F = flicker frequency, I = associated mean critical intensity, and Ii is the intensity at the inflection point of the sigmoid curve relating F to log I.

There is no correlation between quantitative features of the rod and cone portions. Threshold intensities, p, Ii, and Fmax. are separately and independently determined.

The hybrid Black Helleri show quantitative agreement with the Xiphophorus parental stock in the values of p for rods and cones, and in the cone Fmax.; the rod Fmax. is very similar to that for the Platy stock; the general level of effective intensities is rather like that of the Platy form. This provides, among other things, a new kind of support for the duplicity doctrine. Various races of Platypoecilius maculatus, and P. variatus, give closely agreeing values of Im at different flicker frequencies; and two species of sunfish also agree. The effect of cross-breeding is thus not a superficial thing. It indicates the possibility of further genetic investigation.

The variability of the critical intensity for response to flicker follows the rules previously found to hold for other forms. The variation is the expression of a property of the tested organism. It is shown that, on the assumption of a frequency distribution of receptor element thresholds as a function of log I, with fluctuation in the excitabilities of the marginally excited elements, it is to be expected that the dispersion of critical flicker frequencies in repeated measurements will pass through a maximum as log I is increased, whereas the dispersion of critical intensities will be proportional to Im; and that the proportionality factor in the case of different organisms bears no relation to the form or position of the respective curves relating mean critical intensity to flicker frequency. These deductions agree with the experimental findings.
THE RATE OF CO2 ASSIMILATION BY PURPLE BACTERIA AT VARIOUS WAVE LENGTHS OF LIGHT
Authors: French C. S.
Published: May 2004

1. The relative absorption spectrum of the pigments in their natural state in the photosynthetic bacterium Spirillum rubrum is given from 400 to 900 mµ. The position of the absorption maxima in the live bacteria due to each of the pigments is: green pigment, 420, 590, 880; red pigment, 490, 510, 550.

2. The relative absorption spectrum of the green pigment in methyl alcohol has been determined from 400 to 900 mµ. Bands at 410, 605, and 770 mµ were found.

3. The wave length sensitivity curve of the photosynthetic mechanism has been determined and shows maxima at 590 and about 900 mµ.

4. It is concluded that the green bacteriochlorophyll alone and not the red pigment can act as a light absorber for photochemical CO2 reduction.
VISUAL ADAPTATION AND CHEMISTRY OF THE RODS
Authors: Wald George , Clark Anna-Betty
Published: May 2004

1. The reality of a chemical cycle proposed to describe the rhodopsin system is tested with dark adaptation measurements.

2. The first few minutes of rod dark adaptation are rapid following short, slower following long irradiation. As dark adaptation proceeds, the slow process grows more prominent, and occupies completely the final stages of adaptation.

3. Light adaptation displays similar duality. As the exposure to light of constant intensity lengthens, the visual threshold rises, and independently the speed of dark adaptation decreases.

4. These results conform with predictions from the chemical equations.