bluuebunny/crossref_metadata_2025 huggingface dataset:
THE TOXICITY OF COPPER NITRATE SOLUTIONS TO POLYCELIS NIGRA
Authors: White Theodore
Published: May 2004

The estimation of the number of variables operating in cases of toxic action toward living organisms is discussed. The toxicity of glucose, sodium chloride, and copper nitrate solutions to Polycelis nigra has been investigated and also that of copper nitrate solutions whose osmotic pressure was adjusted to a constant level by the addition of glucose or of sodium chloride.

It is shown that hypertonic solutions of copper nitrate are abnormally toxic but that the osmotic variable is not the factor responsible for this abnormally high toxicity. The lack of data which might elucidate such problems is indicated.

During the course of this work it was observed that mixed solutions of copper nitrate + sodium chloride and copper nitrate + glucose exhibit toxicities greater than those expected from consideration of the separate toxicities of the components of the mixtures.
THE ACCELERATION OF SAPONIN HEMOLYSIS BY PROFLAVINE
Authors: Collier H. Bruce
Published: May 2004

Proflavine is a very powerful accelerator of saponin hemolysis of rabbit, human, and dog erythrocytes. Lysolecithin hemolysis, on the other hand, is inhibited.

Dog erythrocytes in the presence of proflavine undergo marked changes in shape, finally becoming rods of about 13 µ in length. Rabbit and human erythrocytes are not altered in form under these conditions.
THE EFFECTS OF CAFFEINE ON OXYGEN CONSUMPTION AND CELL DIVISION IN THE FERTILIZED EGG OF THE SEA URCHIN, ARBACIA PUNCTULATA
Authors: Cheney Ralph Holt
Published: May 2004

1. By means of the Warburg-Barcroft microrespirometer apparatus and the Warburg direct method, the relative effect of caffeine upon the O2 consumption of the fertilized egg of Arbacia punctulata was shown for the following concentrations in sea water: 0.002 per cent (M/10,000), 0.004 per cent (M/5,000), 0.02 per cent (M/1,000), 0.1 per cent (M/200), 0.2 per cent (M/100), 0.5 per cent (M/40), and 2 per cent (M/10).

2. In comparison with the normal eggs (uninhibited, non-caffeine-treated controls), caffeine in concentrations including and greater than 0.1 per cent (M/200) depressed the average uptake from approximately 25 to 61 per cent over the 3 hour period. In a number of instances, as typified by Experiment 10, the effective inhibitory concentration ranged from 0.02 per cent (M/1,000) upward and the degree of depression of the O2 consumption ranged from 10.6 per cent to 60.6 per cent.

3. All caffeine concentrations including and above 0.02 per cent (M/1,000) in the series used, resulted in decreasing the normal rate of cleavage division in the fertilized Arbacia eggs.

4. The higher concentrations (0.5 and 2 per cent) produced a complete blockage of the cleavage process.

5. Complete cleavage inhibition was noted only when the O2 uptake had been depressed to 50 per cent or more of the normal controls.

6. O2 consumption-time relationship data indicate an average depression, in O2 consumption over a 3 hour period, ranging from 25 per cent with a caffeine concentration of 0.1 per cent to a 61 per cent inhibition with a concentration of 2 per cent.

7. Concentrations of less than 0.1 per cent (certainly of less than 0.02 per cent) give variable results and indicate no significant effect.

8. It is inferred from the respiration data presented that it is probable that the inhibition of the O2 consumption in fertilized Arbacia eggs is due to the influence of caffeine upon the main (activity or primary) pathway. It will be observed that there are certain similarities of the caffeine data to the degree of inhibition accomplished by sodium cyanide. Moreover, it has been demonstrated that the cyanide probably acts on the cytochrome oxidase step in the cytochrome oxidase-cytochrome chain of reactions constituting the O2 uptake phase of respiratory metabolism. It is not improbable, therefore, that caffeine also may act upon the cytochrome oxidase enzyme.

9. From the viewpoint of environmental conditions influencing reproductive phenomena, it is of interest that caffeine can affect the normal metabolism of the zygote.
WATER RELATIONS IN THE CELL
Authors: Osterhout W. J. V.
Published: May 2004

Chloroplasts may contract under natural conditions and give up water to the rest of the cell, thus indicating changes in metabolism or constitution. Such contractions may be produced experimentally.

In Nitella the chloroplasts are ellipsoid bodies which, under natural conditions, may contract to spheres with a loss of volume. This may be brought about by lead acetate, ferric chloride, and digitonin: the contraction may occur while the cell is alive. The contraction in lead acetate is reversible (in lead nitrate little or no contraction occurs).

In Spirogyra the chloroplast is a long, spirally coiled ribbon which may contract under natural conditions to a short nearly straight rod with a loss of volume. This can be brought about by inorganic salts and in other ways while the cell is still alive.
THE ACTION SPECTRUM OF SENSITIZATION TO HEAT WITH ULTRAVIOLET LIGHT
Authors: Giese Arthur C. , Crossman Elizabeth B.
Published: May 2004

1. Heat does not sensitize paramecia to ultraviolet light but ultraviolet light sensitizes them to heat. Paramecia of two species (Paramecium caudatum and P. multimicronucleate) are much more readily killed by heat at 42.3° C. if they are first exposed to ultraviolet light.

2. From studies on paramecia irradiated with a given dosage at various wave lengths before being killed by heat, an action spectrum of the compound in the protoplasm being sensitized to heat can be determined. Proteins with absorption similar to that of pseudoglobulin are suggested by these experiments.

3. The effect upon living things differs from that on pure protein systems in that paramecia are not rendered more sensitive to temperatures below the lethal temperature whereas proteins are.

4. Almost complete recovery from ultraviolet light as judged by heat sensitivity occurs within 4 to 5 days.

5. By a study of the rate of recovery from doses at different wave lengths evidence suggesting effects on nucleic acid is obtained.

6. The possible significance of the data and the action spectrum is discussed.
PURIFICATION AND PROPERTIES OF DESOXYRIBONUCLEASE ISOLATED FROM BEEF PANCREAS
Authors: McCarty Maclyn
Published: May 2004

1. A method is described for the isolation and purification of desoxyribonuclease from a 0.25 N sulfuric acid extract of beef pancreas. The activity of the enzyme is measured by a viscosimetric method using sodium desoxyribonucleate from calf thymus as substrate.

2. The enzyme is highly active, a measurable effect being obtained at concentrations of less than 0.01 microgram per cc. In highly dilute solution the enzyme is rapidly inactivated, and the use of a protective agent such as gelatin or peptone is necessary.

3. The purified material contains traces of a proteolytic enzyme, but displays no ribonuclease, lipase, or phosphatase activity.

4. The enzyme requires activation by magnesium or manganese ion, and citrate serves as a potent inhibitor of the magnesium-activated enzyme.

5. Its enzymatic activity is inhibited by the specific antibody present in the serum of rabbits immunized with enzyme protein.
THE EFFECTIVENESS OF THE SPECTRUM IN CHLOROPHYLL FORMATION
Authors: Frank Sylvia R.
Published: May 2004

1. Although the carotenoid pigments are present in large concentration in the plastids of etiolated Avena seedlings as compared with protochlorophyll, the pigment precursor of chlorophyll, it is possible to show that the carotenoids do not act as filters of the light incident on the plant in the blue region of the spectrum where they absorb heavily. This suggests that the carotenoids are located behind the protochlorophyll molecules in the plastids.

2. Since the carotenoids do not screen and light is necessary for chlorophyll formation, an effectiveness spectrum of protochlorophyll can be obtained which is the reciprocal of the light energy necessary to produce a constant amount of chlorophyll with different wavelengths. The relative effectiveness of sixteen spectral regions in forming chlorophyll was determined.

3. From the effectiveness spectrum, one can conclude that protochlorophyll is a blue-green pigment with major peaks of absorption at 445 mµ, and 645 mµ, and with smaller peaks at 575 and 545 mµ. The blue peak is sharp, narrow, and high, the red peak being broader and shorter. This differs from previous findings where the use of rougher methods indicated that red light was more effective than blue and did not give the position of the peaks of absorption or their relative heights.

4. The protochlorophyll curve is similar to but not identical with chlorophyll. The ratio of the peaks of absorption in the blue as compared to the red is very similar to chlorophyll a, but the position of the peaks resembles chlorophyll b.

5. There is an excellent correspondence between the absorption properties of this "active" protochlorophyll and what is known of the absorption of a chemically known pigment studied in impure extracts of seed coats of the Cucurbitaceae. Conclusive proof of the identity of the two substances awaits chemical purification, but the evidence here favors the view that the pumpkin seed substance, which is chemically chlorophyll a minus two hydrogens, is identical with the precursor of chlorophyll formation found in etiolated plants.
SENSITIZATION OF CELLS TO HEAT BY VISIBLE LIGHT IN PRESENCE OF PHOTODYNAMIC DYES
Authors: Giese Arthur C. , Crossman Elizabeth B.
Published: May 2004

1. Visible light of high intensity does not injure paramecia or sensitize them to heat.

2. If photodynamic dyes are added, paramecia are readily killed by visible light of high intensity and are sensitized to heat by sublethal dosages of light.

3. Cells so sensitized are killed when subjected to a sublethal exposure to heat.

4. If the light and heat are applied in the reverse order, namely, heat and then light, no ill effects are observed.

5. When the concentration of dye is reduced a larger light dosage is required.

6. Recovery from sensitization is slow, requiring about 4 days for a ¾ lethal dosage.

7. Sublethal dosages of light in the presence of dyes do not affect the division rate even when ¾ the lethal dosage has been used.

8. A possible explanation for the photodynamic sensitization to heat is discussed.
NERVE AS MODEL TEMPERATURE END ORGAN
Authors: Bernhard C. G. , Granit Ragnar
Published: May 2004

Rapid local cooling of mammalian nerve sets up a discharge which is preceded by a local temperature potential, the cooled region being electronegative relative to a normal portion of the nerve.

Heating the nerve locally above its normal temperature similarly makes the heated region electronegative relative to a region at normal temperature, and again a discharge is set up from the heated region.

These local temperature potentials, set up by the nerve itself, are held to serve as "generator potentials" and the mechanism found is regarded as the prototype for temperature end organs.
THE EXTRACELLULAR RELEASE OF ECHINOCHROME
Authors: Shapiro Herbert
Published: May 2004

A study was made of the diffusion of the red pigment echinochrome from the eggs of the sea urchin, Arbacia punctulata, into sea water.

Unfertilized eggs retained their pigment, over periods of hours. Outward diffusion of pigment from unfertilized eggs normally is entirely negligible, or does not occur at all. Enchancing the calcium or potassium content of the artificial sea water (while retaining isosmotic conditions) did not induce pigment release.

Under anaerobic conditions, unfertilized eggs release pigment in small quantities.

Fertilization alone brings about echinochrome release. Fertilized eggs invariably released pigment, whether in normal sea water, or sea water with increased calcium or potassium. This diffusion of the pigment began during the first cleavage, possibly soon after fertilization.

The pigment release is not a consequence solely of the cell's permeability to echinochrome (or chromoprotein, or other pigment combination) but is preceded by events leading to a release of echinochrome from the granules in which it is concentrated within the cell. These events may be initiated by activation or by anaerobiosis.

The phenomenon was not due to cytolysis.
PHOTOLYTIC LIPIDS FROM VISUAL PIGMENTS
Authors: Bliss Alfred Frederick
Published: May 2004

A method is described for the preservation of iodopsin, the labile photopigment of daylight vision, by freeze drying in vacuo.

The lipids released by the action of light on rhodopsin and iodopsin are found to be similar and to possess a labile absorption spectrum in chloroform, with a rising peak at about 390 mµ and a declining peak in the region of 470 mµ. After the change is complete the absorption spectrum resembles closely that of retinene.
ISOLATION OF HEXOKINASE FROM BAKER'S YEAST
Authors: Berger Louis , Slein Milton W. , Colowick Sidney P. , Cori Carl F.
Published: May 2004

1. A method is described for the isolation of hexokinase from baker's yeast. The method is based mainly on fractionation with alcohol and results

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in a 30-fold increase in specific activity. The final product could be crystallized from ammonium sulfate without change in specific activity.

2. The enzyme catalyzes a transfer of phosphate from adenosinetriphosphate to glucose, fructose, or mannose, the relative rates with these three sugars being 1:1.4:0.3.

3. With glucose as substrate, the turnover number for the crystalline enzyme is 13,000 moles of substrate per 105 gm. of protein per minute at 30° and pH 7.5. The temperature coefficient (Q10°) between 0 and 30° is 1.9.

4. Magnesium ions are necessary for the activity, the dissociation constant for the Mg++ -protein complex being 2.6 x 10–3. Fluoride in concentrations as high as 0.125 M has no inhibitory effect on the enzyme when the Mg++ and orthophosphate concentrations are 6.5 x 10–3 M and 1 x 10–3 M, respectively.

5. The crystalline enzyme shows a loss in activity when highly diluted. This loss in activity can be prevented by diluting in the presence of small amounts of other proteins. Of the various protective proteins tested, insulin was the most effective, providing complete protection in a concentration of 6 micrograms per cc.; with serum albumin, a concentration of 60 micrograms per cc. was necessary. Thiol compounds (cysteine, glutathione) exerted no protective action.

6. The inactivation of the crystalline enzyme on incubation with trypsin can be prevented to a marked degree by the presence of glucose. The instability of crude preparations of yeast hexokinase may be attributed to the presence of proteolytic enzymes, since glucose or fructose has a remarkable protective effect on such preparations.
CULTURE CONDITIONS AND THE DEVELOPMENT OF THE PHOTOSYNTHETIC MECHANISM
Authors: Myers Jack ,   With the Technical Assistance of James Johnston and Helen Davis
Published: May 2004

1. Chlorella pyrenoidosa has been grown in a continuous-culture apparatus under various light intensities provided by incandescent lamps, other conditions of culture being maintained constant. The harvested cells were analyzed for cell number, dry weight, nitrogen, and chlorophyll per unit cell volume.

2. Cell nitrogen and cell volume are parallel measures of cellular material over the range of light intensity studied.

3. The dry weight per cell volume increases slowly with light intensity, showing about a 20 per cent variation.

4. Chlorophyll concentration and cell number show a concomitant decrease with increasing light intensity, varying in such a way that there are always about the same number of chlorophyll molecules per cell. It is considered that this phenomenon has bearing on the interpretation of data which has led to the theory of the photosynthetic unit.
FRACTIONATION OF THE EYE PIGMENTS OF DROSOPHILA MELANOGASTER
Authors: Wald George , Allen Gordon
Published: May 2004

Eye pigments of normal and mutant types of D. melanogaster have been extracted with water and fractionated by chromatographic adsorption on powdered talc. Spectra of all the fractions obtainable in solution have been measured and the general chemical behavior of the pigments is described. Two chemically distinct groups of pigments are found, to be identified with the earlier designated red and brown components. The red component in the wild-type eye contains three well defined pigments, two of them capable of further subdivision so that the total number of fractions obtained is five. There is also present a brown component pigment which could not be treated quantitatively by the methods employed. All members of the wild-type red component are found in cinnabar eyes, unaccompanied by the brown component. Conversely, brown eyes contain a pigment indistinguishable from the wild-type brown component, virtually alone. In sepia eyes, one red component and two brown component pigments can be distinguished, all three pigments differing from those of wild-type eyes. Pigments apparently identical with those found in wild-type melanogaster eyes have also been found in D. virilis.
NATURE OF THE ACTION CURRENT IN NITELLA
Authors: Osterhout W. J. V.
Published: May 2004

The experiments indicate that the protoplasm of Nitella consists of an aqueous layer W with an outer non-aqueous surface layer X and an inner non-aqueous surface layer Y.

The potential at Y is measured by the magnitude of the action curve and the potential at X by the distance from the top of the action curve to the zero line. These potentials appear to be due chiefly to diffusion potentials caused by the activity gradients of KCl across the non-aqueous layers X and Y. The relative mobilities of K+ and Cl- in X and in Y can be computed and an estimate of the activity of KCl in W can be made. In the complete resting state the mobilities of K+ and Cl- in X are not very different from those in Y.

The action curve is due to changes in Y which suddenly becomes very permeable, allowing potassium to move from the sap across Y into W, and thus losing its potential. A gradual loss may be due to changes in ionic mobility in Y.

When recovery is incomplete and Y has not yet regained its normal potential a stimulus may cause a loss of the potential at Y giving an action curve of small magnitude. The magnitude may vary in successive action curves giving what is called a complex pattern in contrast to the simple pattern observed when recovery is complete and all the action curves are alike. Complex patterns occur chiefly in cells treated with reagents. Untreated cells usually give simple patterns.

A variety of complex action patterns is discussed. It is evident that the cells of Nitella show much more variation than such highly specialized cells as muscle and nerve which give stereotyped responses.

In some cases it may be doubtful whether the all-or-none law holds.
MOLECULAR ASSOCIATION OF HEMOCYANIN PRODUCED BY X-RAYS AS OBSERVED IN THE ULTRACENTRIFUGE
Authors: Pickels Edward G. , Anderson Rubert S.
Published: May 2004

1. When normal, monodisperse hemocyanin (60.5S) from Limulus Rolyphemus was irradiated in neutral buffer with x-rays, several new, more rapidly sedimenting ultracentrifugal components (86S, 107S, 122S) were produced, with a corresponding loss in the amount of the unaffected protein. The amount of the effect was roughly proportional to the amount of irradiation.

2. The new resolvable components apparently represented an association of the primary particles into aggregates of 2, 3, and 4 primary particles respectively.

3. The proportional amount of hemocyanin affected decreased almost to the vanishing point as the concentration of the protein was raised to high levels.

4. The absolute effect, i.e. the total number of particles affected in a given volume, increased with the concentration of hemocyanin, at least for concentrations below 15 per cent.

5. The presence of 33 per cent horse serum during irradiation inhibited the effect on the hemocyanin almost completely, with hemocyanin concentrations of both 0.8 and 14 per cent.

6. The presence of 2.8 per cent egg albumin during irradiation lowered the effect by about 70 per cent in the case of dilute preparations (0.8 per cent hemocyanin), but by only about 25 per cent in the case of 14 per cent solutions.

7. A lowering of the solution's oxygen tension during irradiation enhanced the effect, almost doubling it in some cases.

8. The probable theoretical significance of these and other observations are discussed in the text.
THE PROLYTIC LOSS OF K FROM HUMAN RED CELLS
Authors: Ponder Eric
Published: May 2004

The prolytic loss of K., i.e. the loss of K which takes place from red cells exposed to hypolytic concentrations of lysins, has been measured in systems containing distearyl lecithin, sodium taurocholate, sodium tetradecyl sulfate, saponin, and digitonin, by means of the flame photometer. The lysins are added in various concentrations to washed red cells from heparinized human blood, and the K in the supernatant fluids is determined after various intervals of time and at various temperatures. The prolytic loss Kp is compared in every experiment with the loss Ks into standard systems containing isotonic NaCl alone, with no lysin.

The losses Ks and Kp increase with time, so that new steady states are approached logarithmically. The values of Kp which correspond to the new steady states depend on the lysin used, being greatest with taurocholate and smallest with digitonin. The temperature coefficient of the loss is positive, and the extent and course of the losses have no apparent relation to the prolytic shape changes.

In systems in which the loss of K is appreciable, it can be inhibited by the addition of plasma or of either cholesterol or serum albumin. Of these two substances, even when used in quantities which have an approximately equal effect in inhibiting hemolysis, serum albumin is much the more effective.

Just as the prolytic loss of K occurs without the loss of any Hb, so in concentrations of lysin sufficient to produce hemolysis the loss of K, expressed as a percentage of the total red cell K, increases much more rapidly with lysin concentration than does the loss of Hb expressed as a percentage of the total Hb. The explanation of these relations depends on whether the loss of K is treated as being all-or-none in the case of the individual cell or as being the result of the loss of part of the K from all of the cells. This point has still to be decided.
CRYSTALLINE SOYBEAN TRYPSIN INHIBITOR
Authors: Kunitz M.
Published: May 2004

A study has been made of the general properties of crystalline soybean trypsin inhibitor. The soy inhibitor is a stable protein of the globulin type of a molecular weight of about 24,000. Its isoelectric point is at pH 4.5. It inhibits the proteolytic action approximately of an equal weight of crystalline trypsin by combining with trypsin to form a stable compound. Chymotrypsin is only slightly inhibited by soy inhibitor. The reaction between chymotrypsin and the soy inhibitor consists in the formation of a reversibly dissociable compound.

The inhibitor has no effect on pepsin.

The inhibiting action of the soybean inhibitor is associated with the native state of the protein molecule. Denaturation of the soy protein by heat or acid or alkali brings about a proportional decrease in its inhibiting action on trypsin. Reversal of denaturation results in a proportional gain in the inhibiting activity.

Crystalline soy protein when denatured is readily digestible by pepsin, and less readily by chymotrypsin and by trypsin.

Methods are given for measuring trypsin and inhibitor activity and also protein concentration with the aid of spectrophotometric density measurements at 280 mµ.
COMPARATIVE KINETICS OF HEMOLYSIS INDUCED BY BACTERIAL AND OTHER HEMOLYSINS
Authors: Bernheimer Alan W.
Published: May 2004

A study has been made of the kinetics of lysis induced by various hemolytic agents. The course of bemolysis was followed by mixing lysin with washed human erythrocytes, removing samples from the mixture, and estimating colorimetrically the hemoglobin in the supernatant fluid of the centrifuged samples. Most of the curves (but not all of them, e.g. tyrocidine) obtained by plotting degree of hemolysis against time, were S-shaped. The initiation of lysis by streptolysin S' was delayed, and in this property, streptolysin S' was similar to Cl. septicum hemolysin. None of the other lysins studied exhibited a long latent period preceding lysis.

The maximum rate of hemoglobin liberation was found, in the range of lysin concentrations studied, to be a linear function of concentration when theta toxin of Cl. welchii, pneumolysin, tetanolysin, or streptolysin S' was the lytic agent. With comparable concentrations of saponin, sodium taurocholate, cetyl pyridinium chloride, tyrocidine, duponol C, lecithin-atrox venom mixture, or streptolysin O, the relation between rate and concentration was non-linear.

The critical thermal increment associated with hemolysis was determined for systems containing pneumolysin, theta toxin, streptolysin S', streptolysin O, tetanolysin, and saponin.

The findings concerning the effect of concentration and temperature on the rate of hemolysis provide a basis for classifying hemolytic agents (Tables I and II).

Hemolysis induced by Cl. septicum hemolysin was found to be preceded by two phases: a phase of alteration of the erythrocytes and a phase involving swelling. Antihemolytic serum inhibited the first but not the second phase while sucrose inhibited the second but not the first phase.
ACTION OF PAPAIN AND FICIN ON TADPOLES AND ARBACIA EGGS
Authors: Northrop John H.
Published: May 2004

Living tadpoles and Arbacia eggs are not digested by ficin or papain although the dead organisms are.

Arbacia eggs develop in papain solutions but the cells become separated. Development is normal in ficin and trypsin solutions.
THE DARK ADAPTATION OF THE COLOR ANOMALOUS MEASURED WITH LIGHTS OF DIFFERENT HUES
Authors: Chapanis A.
Published: May 2004

Determinations of minimum light thresholds as a function of time in the dark have been made for four color normal, three deuteranopic (or deuteranomalous), and four protanopic (or protanomalous) subjects. Measurements were made with red, reddish orange, yellow, green, violet, and white test lights.

Dark adaptation curves for the deuteranopes and deuteranomalous are essentially identical with those of the color normal for all colors.

The cone portions of the protanopic dark adaptation curves measured with the red, reddish orange, yellow, and white lights are higher than the corresponding data for the color normal, the discrepancy between the two sets of data decreasing from the long to short wave lengths. Dark adaptation curves for the protanopes and protanomalous measured with green and violet light are essentially normal in appearance.

A theoretical explanation is advanced to account for these findings in terms of the known sensitivity characteristics of the normal and color-anomalous eye.
IDENTIFICATION OF MONO-IODOTYROSINE FROM IODINATED PEPSIN
Authors: Herriott Roger M.
Published: May 2004

Isolation of mono-iodotyrosine from slightly iodinated pepsin has been repeated and the properties of the product compared with those of synthetic dl-3-iodotyrosine. Ultraviolet absorption spectra, pK values of the phenol group, solubility measurements, and partition coefficients were so nearly identical for the two materials that there is now no reason to doubt that the product from pepsin is 3-iodotyrosine.
THE RELATION OF ENZYMATIC ADAPTATION TO THE METABOLISM OF ENDOGENOUS AND EXOGENOUS SUBSTRATES
Authors: Spiegelman S. , Reiner John M. , Cohnberg Rosellen
Published: May 2004

The source of energy for enzymatic adaptation has been investigated. Aerobically, it is found that the endogenous carbohydrate reserves may be used as such a source. In cells depleted of their reserves, the adaptive substrate itself can be oxidized even while it cannot be fermented, and so can serve as a source of energy for the adaptation to a fermentative mode of utilization.

Anaerobically, adaptation may occur at the expense of stored energy-rich compounds, while the reserves and the adaptive substrate are now useless as fuel. Such compounds appear to be more plentiful in young than in old cells. The addition of any fermentable substrate, such as glucose, leads to rapid anaerobic adaptation. Experiments in which maltose-adapted cells are adapted anaerobically to galactose with the aid of a little added maltose, and conversely, show that fermentability is the criterion of usefulness for an exogenous substrate in aiding the adaptive process.

None of the endogenous and exogenous energy sources which have been investigated will facilitate adaptation unless the adaptive substrate is present while they are being consumed.

The significance of these findings and the adequacy of "activation" hypotheses to explain enzymatic adaptation has been discussed.
THE CHEMICAL COMPOSITION OF ISOLATED CHROMOSOMES
Authors: Mirsky A. E. , Ris Hans
Published: May 2004

By means of 1 M NaCl isolated lymphocyte chromosomes can be separated into two fractions, each of which contains nucleoprotein. The fraction soluble in M NaCl consists largely of desoxyribose nucleohistone, and constitutes 90 to 92 per cent of the mass of the chromosome. The insoluble residue (the residual chromosome is a coiled thread containing some 12 to 14 per cent of ribose nucleic and about one-fifth as much desoxyribose nucleic acid; the residual chromosome accounts for 8 to 10 per cent of the mass of the chromosome. The staining of chromosomes—whether by the Feulgen procedure, by hematoxylin, orcein, or by basic dyes such as crystal violet—is due to the nucleohistone fraction which contains about 96 per cent of the nucleic acid of the chromosome. The form of the chromosome is due primarily to the protein thread of the residual chromosome. This thread is the only linear structure of microscopic dimensions in the chromosome that is not readily dispersed. When chromosomes are broken, it must be supposed that a break is made in the protein thread of the residual chromosome. The foregoing provides evidence for considering the residual chromosome to be the basis of the linear order of the genes. This would mean either that the residual chromosome is a structure around which the genes are organized or that the genes form part of its substance.
STUDIES ON THE HEMOPHILUS GROUP OF ORGANISMS
Authors: Gilder H. , Granick S.
Published: May 2004

The porphin requirements of the Hemophilus organisms have been studied. Organisms of the parainfluenzae group show quantitative differences in their ability to synthesize heme. The ability of the parainfluenzae organisms to grow appears to depend on the rate with which they synthesize heme and in part at least on the properties of the medium to protect the heme from peroxidative breakdown.

Quantitative studies of the growth of H. influenzae Turner on various iron porphins have been made. Iron protoporphin gives greatest growth when supplied in excess, although iron mesoporphin appears more efficient at lower concentrations. Iron deutero- and iron hematoporphin are much less effective. This suggests that although the vinyl groups are not essential for growth of the Turner organism they may be required for some particular enzymes which aid in attaining maximum growth.

A number of substances potentiate the growth-promoting properties of iron porphins. These substances include reducing agents and agents which destroy H2O2.

E. influenzae Turner appears to require heme for anaerobic as well as aerobic growth. The possibility of an essential heme enzyme functioning under anaerobic conditions must therefore be considered.
BACTERIOPHAGE FORMATION WITHOUT BACTERIAL GROWTH
Authors: Price Winston H.
Published: May 2004

1. The addition of penicillin greatly increases the production of phage in bacterial suspensions containing 2.5 to 3.5 x 108 cells in 0.4 ml. broth plus 6.6 ml. Locke's solution.

2. Addition of niacin also greatly increases the formation of phage in the above system without the addition of penicillin.

3. The results indicate that niacin is necessary for phage production and that bacteria cannot utilize niacin in the presence of penicillin.

4. Staphylococcus muscae will grow in the synthetic medium of Fildes but do not form phage unless broth or yeast extract is added.

5. Phage formation requires the presence of one or more factors, besides niacin, present in broth and yeast extract which are not essential for bacterial growth. Penicillin does not prevent the utilization of the unknown substance or substances by the bacteria.

6. A solution containing biotin, guanine, adenine, ß-alanine, riboflavin, uracil, pyridoxamine, guanylic acid, adenylic acid, yeast nucleic acid, choline, p-aminobenzoic acid, a flavin component from liver, ribose, thymine, xanthine, folic acid, inositol, p-aminophenyl alanine, pantothentic acid and a strepogenin concentrate cannot replace broth or yeast extraction in increasing phage formation in the synthetic medium of Fildes.

7. The results indicate there is a continual competition between the bacteria and phage for certain essential building elements.

8. The results are discussed in relation to possible methods of control of virus diseases.
METHOD FOR OBTAINING KNOWN LOW CONCENTRATIONS OF MUSTARD (H) OR LEWISITE (L) GAS IN AIR
Authors: Northrop John H.
Published: May 2004

Constant small quantities (0.1 to 100 micrograms per hour) of mustard (H) or lewisite (L) gas may be obtained by allowing the vapor to diffuse through a porous alundum plug of suitable dimensions. By regulating the rate of flow of air past the plug known concentrations of the gases in air may be obtained.
A CONVENIENT METHOD FOR POTENTIOMETRIC TITRATION OF CHLORIDE IONS
Authors: Northrop John H.
Published: May 2004

A convenient reference cell and method of potentiometric determination of chloride ions with silver nitrate is described. The method is accurate to about ± 0.02 ml. 10–4 M silver nitrate.
SOME CORRELATIONS BETWEEN DEVELOPMENT AND RESPIRATION IN THE SAND DOLLAR EGG, AS SHOWN BY CYANIDE INHIBITION STUDIES
Authors: Robbie W. A.
Published: May 2004

Cyanide is a valuable tool for studying respiratory mechanisms and their rôle in embryonic development: it is relatively specific in its action, penetrates cell membranes readily, is active in low concentration, and may be controlled quantitatively (page 217).

Echinarachnius is extremely sensitive to cyanide and the oxygen consumption of both eggs and of sperm is almost completely inhibited by 10–5 M HCN (pages 219 and 221). Cell division is likewise arrested by the same concentration (page 223).

One of the pronounced effects of an irreversible dosage of cyanide is the marked cytolysis or breakdown of the egg, both internally and at the cell membrane. This cytolysis appears to be related to the state of metabolism, and its occurrence varies with both the respiratory and developmental activity of the cell (page 224).

The lethal dosage of cyanide varies with the state of development of the egg: the unfertilized egg is less susceptible than the fertilized one, and the susceptibility increases as the development of the fertilized egg proceeds (page 228).

The Echinarachnius egg differs from that of Arbacia in respiratory behavior chiefly in its inability to survive prolonged anoxia: the sea urchin egg will tolerate for 24 hours a concentration of cyanide that kills the sand dollar eggs in 30 minutes (page 229).

The Echinarachnius egg is apparently completely dependent upon cyanide-sensitive catalytic systems for its normal functioning and maintenance. Interference with this aerobic energy release mechanism results in irreversible damage to the egg (page 231).
PHAGE FORMATION IN STAPHYLOCOCCUS MUSCAE CULTURES
Authors: Price Winston H.
Published: May 2004

1. A factor necessary for the formation, of Staphylococcus muscae phage was found in acid digests of many highly purified proteins.

2. The factor is released from egg albumen and pepsin by peptic digestion.

3. No amino acids tried could replace the acid digests of proteins as a source of the factor.

4. The factor, when added to a multiplying bacteria-phage system, cannot be found in purified phage or in the lysate after complete lysis of the system has taken place.
SENSITIZATION TO HEAT BY X-RAYS
Authors: Giese Arthur C. , Heath H. Duane
Published: May 2004

1. Paramecium caudatum is sensitized to heat by sublethal dosages of x-rays. Thus if paramecia are irradiated, then exposed to a sublethal dosage of heat they are killed, but if the same heat exposure precedes the same dosage of radiations, they are not.

2. Sensitivity to both heat and x-rays is much greater in paramecia from the log growth phase than in those from the stationary phase of a culture.

3. Recovery from heat sensitization in animals from the stationary phase of a culture is slow, requiring several days.

4. Division is readily retarded and even temporarily inhibited by sublethal dosage of x-rays. Recovery of the division rate is fairly slow requiring several days.

5. Paramecia can be killed by a dosage of 1,200,000 r (of which about one-half reach the animal) units of x-radiation alone. Smaller dosages are not lethal if the paramecia are transferred to fresh medium immediately upon completion of irradiation.

6. The possibility of utilization of heat sensitization in treatment of malignant growths is discussed.
EVIDENCE OF ACTIVE TRANSFER OF CERTAIN NON-ELECTROLYTES ACROSS THE HUMAN RED CELL MEMBRANE
Authors: LeFevre Paul G.
Published: May 2004

1. Permeability of the human erythrocyte to glycerol, as indicated by the course of hemolysis and volume changes, is depressed by Cu++, Hg++, I2, p-chloromercuribenzoate, and phlorhizin, without effecting general permeability changes. In so far as tested (Cu++, p-ClHgB), these inhibitors delay exit of glycerol from the cell as well as its entry.

2. Permeability to glucose is similarly depressed by I2 and phlorhizin, and is extremely sensitive to Hg++ and p-chloromercuribenzoate, but is not affected by Cu++. An extensive series of other enzyme poisons is without effect in either system.

3. The effects of the sulfhydryl inhibitors are prevented or reversed in the presence of glutathione, cysteine, etc.

4. The kinetics of the volume changes in glucose-saline solutions indicates a mechanism for transport of glucose into the cell, regulated by the existing intracellular concentration, rather than by simple diffusion gradients.

5. The intermediation of a sulfhydryl group at the cell surface, probably an enzymatic phosphorylation, is suggested as an essential step in the passage of glycerol, glucose, and other like substances, across the human red cell membrane.
INTRACELLULAR GROWTH OF BACTERIOPHAGE STUDIED BY ROENTGEN IRRADIATION
Authors: Latarjet Raymond
Published: May 2004

Growing Escherichia coli infected with bacteriophage T2 was x-rayed during the 21 minute latent period which elapses between infection and lysis of the cells. Survival curves of the infected bacteria were determined almost from minute to minute; they disclosed the following facts which are related to the process of phage growth:

During the first 7 minutes, the infective virus particle remains in the cell unique and genetically intact. The host cell synthesizes some ultraviolet-absorbing material probably devoted to building future particles. From the 7th to 9th minute the x-ray resistance of the virus particle increases, probably because of some internal change. Then, multiplication starts and is completed at about the 13th minute, when an average of 130 virulent units is present per cell, displaying an x-ray resistance twice as high as that of the extracellular virus particle. From 13 minutes to the end, the new units progressively recover the x-ray sensitivity of the extracellular virus.

Nothing can be said about either the rate of multiplication between 9 and 13 minutes, or the nature of the multiplying units, except that they are more radiation-resistant (probably smaller) than the extracellular virus.

The first steps of the growth process are favored by an unknown component of the lysate, different from the active particles. Several particles can grow in the same host cell.
METABOLIC CONDITIONS IN CHLORELLA
Authors: Myers Jack , Cramer Marian
Published: May 2004

1. The effect of nitrate reduction and assimilation on the CO2/O2 quotient of gas exchange has been used as an index of the relative rates of carbon and nitrogen assimilation in Chlorella pyrenoidosa. Changes in over-all metabolism induced by starvation, high light intensity, and nitrogen deficiency have been studied in comparison with the metabolism of cells growing at light-limiting intensities.

2. Starvation, which results in depletion of carbohydrate reserves, gives rise to a high CO2/O2 quotient (∼0.9) during photosynthesis and, therefore, a high C/N assimilation ratio. Starved cells apparently restore their normal C/N ratio before becoming growing cells.

3. Under photosynthesis-saturating light intensities cells show the high CO2/O2 quotient (0.9) indicative of a high C/N assimilation ratio. Return to low light intensities is followed by the abnormally low CO2/O2 quotient (∼0.4) of a low C/N assimilation ratio. High light intensity apparently gives rise to a condition of a limiting rate of nitrogen assimilation and to an overflow metabolism analogous to that found in other microorganisms.

4. Nitrogen deficiency leads to a completely carbohydrate metabolism in short time experiments and makes still more pronounced the effects characteristic of high light intensity alone.

5. Considerations of nutritional economy sustain the experimental evidence in establishing the metabolism of cells growing under light-limiting intensities as the normal or reference metabolic condition in Chlorella.
OBSERVATIONS ON THE MOTILITY OF RABBIT SPERMATOZOA IN DILUTE SUSPENSION
Authors: Emmens C. W. , Swyer G. I. M.
Published: May 2004

1. Rabbit spermatozoa suspended in Baker's solution rapidly lose motility at relatively high dilutions. At a concentration of 0.4 million per ml., the spermatozoa from most ejaculates are completely immotile within 2 or 3 hours. The same phenomenon occurs with chloride-free diluents and is therefore not due to the toxic action of chlorides.

2. This rapid immobilisation may be prevented by suspension in cell-free supernatants from other more concentrated suspensions of rabbit semen and by the accessory secretions from a vasectomised buck. The most effective supernatants are those prepared from suspensions of spermatozoa which have been left overnight before centrifuging. Immobilisation may also be prevented by many other agents, the most effective of which are gum arabic, starch, glycogen, and serum proteins (carbohydrate-containing or carbohydrate-free). Yet, in no case is the action of these substances as effective as more concentrated suspension in Baker's solution.

3. The immobilisation is not prevented by catalase, gelatin, agar, or sodium silicate. It is almost certainly not due to the toxic action of traces of heavy metals and is not affected by the use of water doubly distilled over glass in the preparation of the diluent, or by treating the diluent with activated charcoal.

4. Washing with Baker's solution does not cause immobilisation of spermatozoa suspended at 20 million per ml. at a stage at which the concentration of seminal plasma has been reduced to that equivalent to dilution to 0.4 million per ml. Further washing (six repeated centrifugings of 0.2 ml. semen in 4 ml. of Baker's solution) immobilises them. This confirms the opinion that loss of intracellular, or perhaps rather paracellular, material is a responsible agent in the dilution phenomenon.
A RAPID METHOD FOR THE DETERMINATION OF PROTEOLYTIC ACTIVITIES OF ENZYME PREPARATIONS
Authors: Chow Bacon F. , Peticolas Mary-Ann
Published: May 2004

A method has been described for the determination of proteolytic activities of enzyme preparations using casein as substrate. The rate of digestion is proportional to the enzyme concentration used. This relationship is utilized as a measure of the enzyme activity. One unit of activity is defined as the amount which is required to digest casein in 15 minutes at 37.5°C. so that 50 per cent of the protein in 1 ml. of 0.25 per cent solution is not precipitable by trichloroacetic acid. This method has been used to determine the activity of enzymes from different sources and also used to follow the rate of activation of enzymes.
ISOLATION OF CRYSTALLINE RICIN
Authors: Kunitz M. , McDonald Margaret R.
Published: May 2004

A toxic crystalline protein has been isolated from crude extracts of castor bean meal. Ultracentrifuge and electrophoresis tests show the crystalline protein to become fairly homogeneous after three or four crystallizations. This is also confirmed by toxicity measurements. Solubility tests, however, indicate the presence of more than one protein component in the crystalline material, possibly in the form of a solid solution which cannot be separated into its components by repeated crystallization under the present technique.
THE EFFECT OF SODIUM CHLORIDE ON PHAGE FORMATION BY STAPHYLOCOCCI AT ELEVATED TEMPERATURES
Authors: Fong J. , Krueger A. P.
Published: May 2004

In experiments with the K strain of Staphylococcus aureus and the K race of bacteriophage suspended in tryptose phosphate broth and maintained at 42°C. it was found that the presence of 1 M NaCl produced certain drastic changes in the relationship between the host cells and the infecting virus:

1. Staphylococci grown at 42°C. in plain broth or in NaCl-broth are "activated," i.e. when growth is stopped by lowering the temperature to 5°C. and phage is added, the activity titre immediately displays a rise of 15- to 16-fold.

2. 1 M NaCl tends to prevent the sorption of phage by cocci and this effect is more pronounced at 42°C. than at 5°C. When the activation test is conducted at 5°C. (the usual temperature) most of the phage is picked up by the cells and the described increase in activity titre follows. If the test takes place at 42°C. there is little sorption and correspondingly little rise in phage titre.

3. Mixtures of staphylococci and phage incubated at 42°C. in NaCl-broth fail to produce phage; the final plaque and activity titres are identical with the initial titres. Here, also, the influence of 1 M NaCl in preventing contact of phage with cocci appears to account for the results.

4. Similar mixtures held at 42°C. in plain broth exhibit a drop of about 60 per cent in activity and plaque titres. The loss of phage may be due to adsorption on dead cells accumulating in the suspension or to the thermolability of the bacterium-phage complex, or to both.
EFFECTS OF HETEROLOGOUS SERA ON FERTILIZED RABBIT OVA
Authors: Chang M. C.
Published: May 2004

Undiluted blood serum of various species was used to culture two-celled rabbit ova for 24 hours. It was found that there is an ovocidal factor present in the serum of man, sheep, cattle, goat, and fowl. The factor is lethal rather than inhibitory; exposure to it for 10 minutes will cause the death of the ova. This factor is unstable, thermolabile (destroyed at 55°C. in 30 minutes), and of large molecular size. The strength or concentration of this factor varies according to the origin of the serum, increasing in the order man, sheep, cattle, goat, fowl. The blood serum of rabbit, horse, dog, guinea pig, rat, and pig contains no ovocidal factor against rabbit ova. The ovocidal factor differs from the spermicidal factor, which is present in all the sera of the different species studied with rabbit spermatozoa. Immunization of the guinea pig against rabbit ova is possible. Normal development of young rabbits was obtained by transplantation of ova cultured in the heated or normal serum of other species after 24 hours.