bluuebunny/crossref_metadata_2025_split huggingface dataset:
DELAYED POTASSIUM EFFECT IN NITELLA
Authors: Hill S. E. , Osterhout W. J. V. 
Published: May 2004

In normal cells of Nitella replacement of NaCl by KCl makes the P.D. much less positive: this is called the potassium effect.
Cells which have lost the potassium effect usually show little or no change of P.D. when NaCl is replaced by KCl but an occasional cell responds after a delay.
It seems possible that the delay may be largely due to the time required for potassium to combine with an organic substance, thus forming a compound which sensitizes the protoplasmic surface to the action of potassium.
NATURE OF THE ACTION CURRENT IN NITELLA
Authors: Hill S. E. , Osterhout W. J. V. 
Published: May 2004

Treatment of Nitella with NaCl greatly reduces the time required for the action current and produces an action curve with one peak instead of the customary two. The time may be reduced to 0.6 second in place of the usual 15 to 30 seconds.
This might be expected if the treatment increased the conductivity of the aqueous part of the protoplasm. The experiments favor this idea although they do not prove its correctness.
This effect is prevented by calcium, possibly because calcium inhibits penetration of salts. That penetration is an important factor is indicated by the fact that salts which might be expected to penetrate rapidly have the most effect. Thus NaSCN is more effective than NaCl but Na2SO4 has little or no effect. The action of NH4Cl and LiCl is similar to that of NaCl.
CHEMICAL CHANGES IN THE ADDUCTOR MUSCLE OF THE CHELIPED OF THE CRAYFISH IN RELATION TO THE DOUBLE MOTOR INNERVATION
Authors: Bergren W. R. , Wiersma C. A. G. 
Published: May 2004

An investigation has been made of the phosphate and lactic acid changes in the adductor muscle of the cheliped of the crayfish Cambarus clarkii upon stimulation of the isolated axons for the fast and slow contractions at determined frequencies. The data obtained point to the following conclusions:
1. When the mechanical effects of the two types of contraction are the same, the chemical changes are of the same order. If the mechanical effects are different, the chemical changes likewise are not equivalent. This is especially to be seen in the case of stimulation at 50 shocks per second: a slowly rising, long continued, strong slow contraction takes place with no apparent change in the phosphate content; a quickly rising fast contraction occurs with a large increase in the phosphate.
2. Since equivalent chemical changes accompany equivalent mechanical action, the two types of contraction do not differ in the essential mechanism of the chemical changes involved, and only one type of contractile substance is present.
3. Even when a contraction has taken place to the maximum extent obtainable, only enough phosphate is found to correspond to one-fifth to one-third of the available phosphagen.
FORMATION OF NEW CRYSTALLINE ENZYMES FROM CHYMOTRYPSIN
Authors: Kunitz M. 
Published: May 2004

A solution of chymotrypsin on slight hydrolysis undergoes an irreversible change into new proteins, two of which are enzymes and have been isolated in crystalline form. The new crystalline enzymes, called beta and gamma chymotrypsins, differ from the original chymotrypsin as well as from each other in many physical and chemical respects, such as molecular weight, crystalline form, solubility, and combining capacity with acid. The new enzymes still possess the same enzymatic properties as chymotrypsin. It thus appears that the irreversible change from chymotrypsin to the new enzymes does not affect the structure responsible for the enzymatic activity of the molecule.
The solubility curves of the new enzymes agree approximately with the curves for a solid phase of one component and furnish very good evidence that the preparations represent distinct substances. The various enzymes when mixed at the proper pH have a tendency to form mixed crystals of the solid solution type. Thus at pH 4.0 gamma chymotrypsin combines to form solid solution crystals with either alpha or beta chymotrypsin. Hence at this pH separation of gamma from either alpha or beta by means of fractional crystallization is impossible. At pH 5.0–6.0, however, each material crystallizes in its own characteristic form and at its own rate; thus a fractional separation of the various enzymes from each other becomes feasible.
EFFECT OF THE FORMATION OF INERT PROTEIN ON THE KINETICS OF THE AUTOCATALYTIC FORMATION OF TRYPSIN FROM TRYPSINOGEN
Authors: Kunitz M. 
Published: May 2004

A solution of crystalline trypsinogen in dilute buffer containing a trace of active trypsin when allowed to stand at pH 5.0–9.0 and 5°C. is gradually transformed partly into trypsin protein and partly into an inert protein which can no longer be changed into trypsin either by enterokinase or mold kinase.
During the process of formation of trypsin and inert protein the ratio of the concentrations of the two products in any reaction mixture remains constant and is independent of the original concentration of trypsinogen protein. This ratio varies, however, with the pH of the solution, the proportion of trypsin formed being greater in the acid range of pH.
The experimental curves for the rate of formation of trypsin, as well as for the rate of formation of inert protein are symmetrical S shaped curves closely resembling those of simple autocatalytic reactions.
The kinetics of formation of trypsin and inert protein can be explained quantitatively on the theoretical assumptions that both reactions are of the simple unimolecular type, that in each case the reaction is catalyzed by trypsin, and that the rate of formation of each of the products is proportional to the concentration of trypsin as well as to the concentration of trypsinogen in solution.
THE GROWTH OF BACTERIOPHAGE
Authors: Ellis Emory L. , Delbrück Max 
Published: May 2004

1. An anti-Escherichia coli phage has been isolated and its behavior studied.
2. A plaque counting method for this phage is described, and shown to give a number of plaques which is proportional to the phage concentration. The number of plaques is shown to be independent of agar concentration, temperature of plate incubation, and concentration of the suspension of plating bacteria.
3. The efficiency of plating, i.e. the probability of plaque formation by a phage particle, depends somewhat on the culture of bacteria used for plating, and averages around 0.4.
4. Methods are described to avoid the inactivation of phage by substances in the fresh lysates.
5. The growth of phage can be divided into three periods: adsorption of the phage on the bacterium, growth upon or within the bacterium (latent period), and the release of the phage (burst).
6. The rate of adsorption of phage was found to be proportional to the concentration of phage and to the concentration of bacteria. The rate constant ka is 1.2 x 10–9 cm.8/min. at 15°C. and 1.9 x 10–9 cm.8/min. at 25°.
7. The average latent period varies with the temperature in the same way as the division period of the bacteria.
8. The latent period before a burst of individual infected bacteria varies under constant conditions between a minimal value and about twice this value.
9. The average latent period and the average burst size are neither increased nor decreased by a fourfold infection of the bacteria with phage.
10. The average burst size is independent of the temperature, and is about 60 phage particles per bacterium.
11. The individual bursts vary in size from a few particles to about 200. The same variability is found when the early bursts are measured separately, and when all the bursts are measured at a late time.
CHANGES OF APPARENT IONIC MOBILITIES IN PROTOPLASM
Authors: Osterhout W. J. V. 
Published: May 2004

In Nitella, as in Halicystis, guaiacol increases the mobility of Na+ in the outer protoplasmic surface but leaves the mobility of K+ unaffected. This differs from the situation in Valonia where the mobility of Na+ is increased and that of K+ is decreased.
The partition coefficient of Na+ in the outer protoplasmic surface is increased and that of K+ left unchanged.
Recovery after the action current is delayed in the presence of guaiacol and the action curves are "square topped."
FORMATION OF TRYPSIN FROM CRYSTALLINE TRYPSINOGEN BY MEANS OF ENTEROKINASE
Authors: Kunitz M. 
Published: May 2004

Crystalline trypsinogen is most readily and completely transformed into trypsin by means of enterokinase in the range of pH 5.2–6.0 at 5°C. and at a concentration of trypsinogen of not more than 0.1 mg. per ml. The action of enterokinase under these conditions is that of a typical enzyme. The process follows closely the course of a catalytic unimolecular reaction, the rate of formation of trypsin being proportional to the concentration of enterokinase added and the ultimate amount of trypsin formed being independent of the concentration of enterokinase.
The catalytic action of enterokinase on crystalline trypsinogen in dilute solution at pH more alkaline than 6.0 and in concentrated solution at pH even slightly below 6.0 is complicated by the partial transformation of the trypsinogen into inert protein which can no longer be changed into trypsin even by a large excess of enterokinase. This secondary reaction is catalyzed by the trypsin formed and the rate of the reaction is proportional to the concentration of trypsin as well as to the concentration of trypsinogen in solution. Hence under these conditions only a small part of the trypsinogen is changed by enterokinase into trypsin while a considerable part of the trypsinogen is transformed into inert protein, the more so the lower the concentration of enterokinase used.
The kinetics of the formation of trypsin by means of enterokinase when accompanied by the formation of inert protein can be explained quantitatively on the theoretical assumption that both reactions are of the simple catalytic unimolecular type, the catalyst being enterokinase in the first reaction and trypsin in the second reaction.
THE FLICKER RESPONSE CONTOUR FOR THE ISOPOD ASELLUS
Authors: Crozier W. J. , Wolf Ernst , Zerrahn-Wolf Gertrud 
Published: May 2004

The flicker response contour for the isopod Asellus is a simple probability integral (F - log I) over the whole determinable range (F = 1 to 51). This contrasts with the "distorted" asymmetrical curves obtained with Apis, Anax, and other arthropods with large convex eyes. The explanation of the distortion as due to mechanical conditions affecting photoreception is therefore confirmed, as the structure of the Asellus eye does not make such a factor likely to be expected for this case.
The Asellus curve agrees with the only other available complete and uncomplicated flicker response contour (from Pseudemys, turtle with rod-free retina), in showing the superiority of the probability integral formulation as compared with certain others which have been suggested.
It is noted as a curious and probably important fact that the relative dispersion of the intensity thresholds (σ'log I) for the elements implicated in determining the flicker contour appears to be identical in bee, dragon fly nymph, and isopod. Other relevant information derived from similar experiments with vertebrates shows that this quantity is specifically determined by the organization of the animal. The nature of the common feature of neural organization in three such diverse arthropods, as contrasted with the diversity seen within one class of vertebrates (e.g., teleosts), remains to be discovered.
MEMBRANE AND PROTOPLASM RESISTANCE IN THE SQUID GIANT AXON
Authors: Cole Kenneth S. , Hodgkin Alan L. 
Published: May 2004

The direct current longitudinal resistance of the squid giant axon was measured as a function of the electrode separation. Large sea water electrodes were used and the inter-electrode length was immersed in oil. The slope of the resistance vs. separation curve is large for a small electrode separation, but becomes smaller and finally constant as the separation is increased.
An analysis of the resistance vs. length curves gives the following results. The nerve membrane has a resistance of about 1000 ohm cm.2 The protoplasm has a specific resistance of about 1.4 times that of sea water. The resistance of the connective tissue sheath outside the fiber corresponds to a layer of sea water about 20µ in thickness. The characteristic length for the axon is about 2.3 mm. in oil and 6.0 mm. in sea water.
THE EFFECTS OF ULTRAVIOLET RADIATION ON SPORES OF THE FUNGUS ASPERGILLUS NIGER
Authors: Zahl Paul A. , Koller L. R. , Haskins C. P. 
Published: May 2004

The survival ratio of Aspergillus spores exposed to ultraviolet radiation has been measured as a function of total incident energy for wave lengths of 2537 Å, 3022 Å, 3129 Å, and 3650 Å.
The effect of humidity on killing of Aspergillus spores by ultraviolet radiation has been found to be negligible.
A delay in germination as a result of irradiation has been found.
The Bunsen-Roscoe reciprocity law has been found to hold within the limits of the radiation intensities studied.
Certain morphological changes have been observed.
THE KINETICS OF PENETRATION
Authors: Jacques A. G. 
Published: May 2004

The rate of entrance of electrolyte and of water into impaled cells of Halicystis Osterhoutii is unaffected by raising the pH of the sea water to 9.2 or lowering it to 7.0. It is quite possible that sodium enters by combining with an organic acid HX produced by the protoplasm. If the pK' of this acid is sufficiently low the change in external pH would not produce much effect on the rate of entrance of sodium.
The rate of entrance of electrolytes is affected by light. In normal light (i.e. natural succession of daylight and darkness) the rate is about twice as great as in darkness.
ON THE RELATION BETWEEN BIRTH WEIGHT AND LITTER SIZE, IN MICE
Authors: Crozier W. J. 
Published: May 2004

For mice, as for various other mammals, the relation between number N of young in a litter and the weight W of the litter can be expressed as W = aNK. For adequately homogeneous data K has the nonspecific value 0.83. With data not homogeneous with respect to certain conditions the equation may still be descriptive, but with K higher than 0.83.
Two kinds of mice obeying this formulation, with the same K, are an albino strain (AA) and a flex-tail foetal anemic (aa). Their ideal weights of a litter of 1 (W1, free from effects of intrauterine competition) are quite different. Their F1 offspring (from AA mothers) give W1 precisely intermediate.
To test the partition theory for the basis of the parabolic equation, backcross and F2 litters were obtained in which for a span of litter sizes there occurred various proportions of anemic to non-anemic young. For equal numbers of each in the same litters the relation of weight of aa to weight of Aa young is again described by Wa = aWAK, and as before K = 0.83.
Examination of the weights of anemic and of non-anemic young, for various proportions of the two in litters of different total numbers, shows that the partition theory can account for a number of the curious relations, including the fact that aa young and Aa young if in mixed litters increase in weight more for an increment of 1 in the litter than if in unmixed litters of the same N. This mechanical result of partitioning can be regarded as a kind of model for heterosis resulting from developmental disharmony.
THE REACTIONS OF IODINE AND IODOACETAMIDE WITH NATIVE EGG ALBUMIN
Authors: Anson M. L. 
Published: May 2004

The following experimental results have been obtained.
1. Native egg albumin treated with iodine and then denatured no longer gives a nitroprusside test or reduces dilute ferricyanide in neutral Duponol PC solution.
2. More iodine is needed to abolish the ferricyanide reduction if the reaction between native egg albumin and iodine is carried out at pH 6.8 than if the reaction is carried out at pH 3.2. At pH 6.8 iodine reacts with tyrosine as well as with cysteine.
3. Cysteine and tryptophane are the only amino acids with reducing groups which are known to react with dilute iodine at pH 3.2 The reducing power of cysteine is abolished by the reaction with iodine, whereas the reducing power of tryptophane remains intact. Pepsin and chymotrypsinogen which contain tryptophane but not cysteine, do not react at all with dilute iodine at pH 3.2.
4. Native egg albumin treated with iodoacetamide at pH 9.0 and then denatured by Duponol PC reduces only 60 per cent as much dilute ferricyanide as egg albumin which has not been treated with iodoacetamide.
5. The SH group is the only protein reducing group which is known to react with iodoacetamide.
The simplest explanation of the new observation that the SH groups of egg albumin can be modified by reactions with the native form of the protein is that the native egg albumin has free and accessible but relatively unreactive SH groups which can react with iodine and iodoacetamide despite the fact that they do not react with ferricyanide, porphyrindin, or nitroprusside.
Preliminary experiments suggested by the results with egg albumin indicate that the tobacco mosaic virus is modified by iodine at pH 2.8 without being inactivated and that the tobacco mosaic and rabbit papilloma viruses are not inactivated by iodoacetamide at pH 8.0.
STUDIES ON CELL METABOLISM AND CELL DIVISION
Authors: Clowes G. H. A. , Krahl M. E. 
Published: May 2004

1. The effects of a number of respiratory inhibiting agents on the cell division of fertilized eggs of Arbacia punctulata have been determined. For eggs initially exposed to the reagents at 30 minutes after fertilization at 20°C., the levels of oxygen consumption prevailing in the minimum concentrations of reagents which produced complete cleavage block were (as percentages of the control): In 0.4 per cent O2-99.6 per cent N2, 32; in 0.7 per cent O2-99.3 per cent CO, 32; in 1.6 x 10–4M potassium cyanide, 34; in 1 x 10–3M phenylurethane, 70; in 4 x 10–3M 5-isoamyl-5-ethyl barbituric acid, 20; in 3 x 10–4M iodoacetic acid, 53.
2. The carbon monoxide inhibition of oxygen consumption and cell division was reversed by light. The percentage inhibition of oxygen consumption by carbon monoxide in the dark is described by the usual mass action equation with K, the inhibition constant, equal to approximately 60, as compared to values of 5 to 10 for yeast and muscle. In 20 per cent O2-80 per cent CO in the dark there was a slight stimulation of oxygen consumption, averaging 20 per cent.
3. Spectroscopic examination of fertilized and unfertilized Arbacia eggs reduced by hydrosulfite revealed no cytochrome bands. The thickness and density of the egg suspension was such as to indicate that, if cytochrome is present at all, the amount in Arbacia eggs is extremely small as compared to that in other tissues having a comparable rate of oxygen consumption.
4. Three reagents poisoning copper catalyses, potassium dithio-oxalate (10–2M), diphenylthiocarbazone (10–4M), and isonitrosoacetophenone (2 x 10–3M) produced no inhibition of division of fertilized Arbacia eggs.
5. These results indicate that the respiratory processes required to support division in the Arbacia egg may perhaps differ in certain essential steps from the principal respiratory processes in yeast and muscle.
THE PIGMENT-PROTEIN COMPOUND IN PHOTOSYNTHETIC BACTERIA
Authors: French C. S. 
Published: May 2004

1. Photosynthetic bacteria in water suspension break open when treated with supersonic vibration thus liberating the cell contents, including a water soluble protein to which is attached the otherwise water insoluble pigments, bacteriochlorophyll and carotinoids. Both types of pigments appear to be combined with the same protein.
2. The protein pigment compound is insoluble in the region of pH 3.0 to 4.5 and in neutral solution can be completely precipitated by 0.5 saturated (NH4)2SO4. It is soluble in distilled water and adsorbable on fullers' earth.
3. Supersonic extracts of photosynthetic bacteria do not have the ability to carry on photosynthesis, but will act as a photocatalyst for the oxidation of ascorbic acid with visible or infrared radiation. The rate of the photochemical oxidation is proportional to the light intensity.
THE CELL SAP OF HYDRODICTYON
Authors: Blinks L. R. , Nielsen John P. 
Published: May 2004

Analysis of the cell sap of Hydrodictyon patenaeforme Pocock, from California indicates the usual marked accumulation of potassium, which is 4000 times as concentrated as in the surrounding pond water. Small amounts of sodium and calcium were found. Chloride makes up about three-fourths of the anions, with a very high sulfate, and much lower bicarbonate concentration accounting for most of the remainder. Electrical conductivity and osmotic studies indicate that the analyzed elements are ionized, and account for most of the sap's osmotic pressure. pH is 5.5 to 6.0.
The analytical procedure was designed to determine as many of the cations as possible on one small sample.
Hydrodictyon is a large multinucleate cell belonging to an order (Chlorococcales) new to permeability and accumulation studies.
THE COMPOSITION OF FLUIDS AND SERA OF SOME MARINE ANIMALS AND OF THE SEA WATER IN WHICH THEY LIVE
Authors: Cole William H. 
Published: May 2004

1. The electrolyte composition, the pH, and freezing points of the fluids of several invertebrates and one primitive chordate are reported.
2. Fluids of the worms, echinoderms, and the clam Venus were isotonic with sea water; fluids of the Arthropoda were hypertonic to sea water.
3. The pH of all fluids was below that of sea water. In the Arthropoda and Myxine less individual variation in pH appeared than in the echinoderms and worms.
4. Ratios of ionic concentrations in the fluid to those in the sea water indicated (1) uniform distribution of ions between the internal and external media for the echinoderms and Venus, (2) differential distribution of potassium and magnesium in the worms; (3) differential distribution of sulfate, magnesium, potassium, and calcium in the Arthropoda; and (4) differential distribution of calcium, magnesium, and sulfate in Myxine.
5. The unequal distribution of ions implies the expenditure of energy against a concentration gradient across the absorbing or excreting membranes, a capacity frequently overlooked in the invertebrates.
6. The sera of the Arthropoda from diluted sea water showed higher concentrations of sodium, potassium, calcium, and chloride ions relative to the respective concentrations in the external medium than in normal sea water, and also showed different orders for those ions.
7. The increase in osmotic pressure of the sera of the animals moving into brackish water is caused by unequal accumulation of sodium, potassium, calcium, and chloride ions. Sulfate and magnesium ionic ratios do not change.
ADSORPTION OF BACTERIOPHAGE UNDER VARIOUS PHYSIOLOGICAL CONDITIONS OF THE HOST
Authors: Delbrück M. 
Published: May 2004

1. The adsorption rate constant of phage to bacterium is found to change between wide limits, depending on the physiological state of the bacterium.
2. The experiments of Krueger and of Schlesinger on the residual free phage in contact with an excess of bacteria are discussed and the view of Schlesinger, that they represent phage particles with reduced affinity to the bacterial host is supported by experiments.
3. The theory of von Smoluchowski and Schlesinger is compared with the experiments.
4. The implications of these findings for the assay methods currently used are discussed.