bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECT OF UNILATERAL ULTRAVIOLET LIGHT ON THE DEVELOPMENT OF THE FUCUS EGG
Authors: Whitaker D. M.
Published: May 2004

1. When Fucus eggs which have been fertilized for a sufficient length of time are irradiated unilaterally with monochromatic ultraviolet light (λ2804 Å) of adequate dosage, 97–100 per cent form rhizoids on the halves of the eggs away from the source of radiation (see Figs. 1 and 2).

2. The responsiveness of the eggs increases gradually after fertilization and does not reach a maximum until about 7 hours at 15°C. (see Fig. 3). The first rhizoids begin to form in a population at about 12 hours after fertilization. The responsiveness remains maximal until at least 11 hours after fertilization.

3. It is suggested that the low responsiveness of a population of eggs at an earlier period is due to recovery from the effects of irradiation before the rhizoids begin to form.

4. The response of eggs to λ2804 Å is proportional, over a wide range, to the logarithm of the dosage (see Fig. 1). Dosage was regulated by the duration of exposure during the period of maximum response.

5. High dosages of λ2804 Å, of the order of 10,000 ergs per mm.2, cause the rhizoids to form fairly precisely away from the source of radiation (see Fig. 2). Twice this dosage inhibits rhizoid formation altogether without causing cytolysis.

6. Other wave-lengths which have also been shown to be effective are: 3660, 3130, 2654, 2537, 2482, and 2345 Å. Only exploratory measurements have been made to test the effectiveness of these wave-lengths, but they show that much greater energy is necessary to obtain a strong response with λ3130 and 3660 Å, especially the latter. The wave-lengths shorter than 2804 Å, on the other hand, show the same order of effectiveness as λ2804 Å. Some may be more effective.

7. A beam of λ2804 Å which is incident on a single layer of Fucus eggs is completely extinguished at 2, 3, 6, or 6½ hours after fertilization. About 85 per cent of a beam of λ3660 Å is extinguished. The wave-length 3660 Å is thus not so completely absorbed as λ2804 Å, but the difference in proportion absorbed by the egg is not nearly so great as the difference in effectiveness.
STUDIES ON INVERTEBRATE HEMOGLOBINS (ERYTHROCRUORINS)
Authors: Salomon Kurt
Published: May 2004

1. Two high molecular invertebrate hemoglobins (the erythrocruorins of Lumbricus terrestris and of Nereis virens) as well as the low molecular erythrocruorin of Glycera dibranchiata Ehlers were studied. Their physical chemical properties were compared with those of vertebrate hemoglobin.

2. The hemin of the blood pigment of Glycera dibranchiata Ehlers was shown to be identical with that of vertebrate hemoglobin.

3. The dissociation rates of Glycera and human oxyhemoglobin were measured in the reaction meter of DuBois and t50 (half time of the reaction) was found to be identical (0.027 second) for the two pigments. The t50 value for the high molecular Lumbricus erythrocruorin was 0.070 second.

4. The chemical constitution and physical chemical properties of erythrocruorins were compared with those of vertebrate hemoglobin and of hemocyanin.
THE INFLUENCE OF AGE, HYPOPHYSECTOMY, THYROIDECTOMY, AND THYROXIN INJECTION ON SIMPLE REACTION TIME IN THE RAT
Authors: Brody E. Bloor
Published: May 2004

Thyroxin injection with associated increases in metabolic rate does not significantly affect simple reaction time to an electric shock. Hypophysectomy and thyroidectomy with associated decreases in metabolic rate produce a slight decline in reaction speed. Reaction time is long in young animals, probably due to incomplete development of certain integrative and conductive systems; it remains virtually constant between puberty and relatively advanced age when it increases rapidly, probably due to physicochemical changes in the composition of the conducting nervous system.
THEORY AND MEASUREMENT OF VISUAL MECHANISMS
Authors: Crozier W. J. , Wolf Ernst
Published: May 2004

Comparison of monocular and binocular critical flash intensities for recognition of flicker, using a centrally fixated square image subtending ca. 6.13° on a side (white light), shows that for the cone segment of the response contour the inflection point of the probability integral correlating flash frequency F (for symmetrical flicker) and log mean critical flash intensity Im is with the binocular measurements exactly intermediate between those for each eye separately. This does not mean that in general the data are intermediate; they are not; the binocular asymptotic Fmax. agrees with or lies above the greater one of the two uniocular curves. The entire contour must be considered for valid intercomparisons, as is also true if homologous curves for different observers are to be compared. For the measurements in the predominantly rod region the binocular data are more or less intermediate. The rod curves result, however, from the integrative interplay of rod and cone effects for which the intrinsic curves overlap. The resultant rod curve as measured is determined by the partial inhibition of rod effects by cone effects, and by the summation of the remaining rod contributions with those labelled cone in origin. It is pointed out that in this respect, as in others, it is desirable to consider the rôles of retinal area, and location, from the standpoint of integration of neural effects. These phenomena are essentially independent of the light-time fraction and of the spectral (λ) quality of the light used.

For binocular, as for uniocular excitation, the normal probability summation provides an efficient general description, under diverse conditions of size and location of retinal image, wave-length composition of light, light-time cycle-fraction, and kind of animal. It is pointed out that this is the only function abstractly likely to exhibit this kind of efficiency.

That a summation of veritable effects independently generated by simultaneous, symmetrical uniocular excitation does occur in the recognition of flicker is specifically demonstrated by the fact that for a given mean critical flash intensity the associated variation is lower for binocular than for either or the average of the single-eyed presentations,—and in the ratio not statistically different from 1:1.41; the relative scatter of the binocular indices of dispersion is also reduced below the uniocular. Since the mean variation of the critical intensity is statistically in a constant ratio to Im, in appropriately homogeneous series, independent for example of the brightness level and of the light-time fraction, this signifies an essential doubling of the effectiveness (potential) of each of the elements concerned in the discrimination of flicker when binocular excitation is concerned, although the total number of these elements is only slightly or not at all affected. The potential in question is not exclusively correlated with subjective brightness-at-fusion, which is, however, increased with binocular regard.
THE ACTION OF SODIUM DODECYL SULFATE ON THE CHLOROPHYLL-PROTEIN COMPOUND OF THE SPINACH LEAF
Authors: Smith Emil L.
Published: May 2004

1. Sodium dodecyl sulfate (SDS) attacks the chlorophyll-protein compound modifying its protein properties and absorption spectrum.

2. In the presence of SDS, chlorophyll is quantitatively converted to phaeophytin; i.e., magnesium is removed from the molecule. This reaction, measured spectrophotometrically, proceeds at a rate directly proportional to the hydrogen ion concentration. At constant pH, the rate is proportional to the SDS concentration until a maximum rate is achieved.

3. The chlorophyll or phaeophytin (depending on the pH) remains attached to the protein, since the prosthetic group cannot be separated by ultrafiltration, dialysis, or fractional precipitation.

4. This suggests that the magnesium plays no part in binding chlorophyll to the split protein fragments, but may be concerned in binding the larger units, since the metal becomes extremely labile when the protein is split.
SULFHYDRYL GROUPS OF EGG ALBUMIN IN DIFFERENT DENATURING AGENTS
Authors: Mirsky A. E.
Published: May 2004

1. The reaction between ferricyanide and egg albumin in solutions of urea, guanidine hydrochloride, and Duponol has been investigated.

2. In neutral medium ferricyanide oxidizes all the SH groups of egg albumin that give a color reaction with nitroprusside. In neutral medium ferricyanide appears to react only with the SH groups of egg albumin. The quantity of ferrocyanide formed can accordingly be considered the equivalent of the number of SH groups in egg albumin detectable with nitroprusside.

3. In solutions of urea, guanidine hydrochloride, and Duponol sufficiently concentrated so that all the egg albumin present is denatured, the same number of SH groups are found—equivalent to a cysteine content of 0.96 per cent.

4. In denaturation of egg albumin loss of solubility (solubility not in presence of the denaturing agent, but solubility examined in water at the isoelectric point) and appearance of reactive SH groups are integral parts of the same process. As denaturation proceeds in urea, SH groups are liberated only in the egg albumin with altered solubility and in this albumin the maximum number of SH groups is liberated. In a molecule of egg albumin either all of its SH groups that give a test with nitroprusside are liberated or none of them are.
SULFHYDRYL GROUPS IN FILMS OF EGG ALBUMIN
Authors: Mirsky A. E.
Published: May 2004

1. The same number of SH groups reduces ferricyanide in surface films of egg albumin as in albumin denatured by urea, guanidine hydrochloride, Duponol, or heat, provided the ferricyanide reacts with films while they still are at the surface and with the denatured proteins while the denaturing agent (urea, heat, etc.) is present.

2. The SH groups of a suspension of egg albumin made by clumping together many surface films react with ferricyanide in the same sluggish and incomplete manner as do the groups in egg albumin denatured by concentrated urea when the urea is diluted or in albumin denatured by heat when the solution is allowed to cool off.

3. The known change in configuration of the egg albumin molecule when it forms part of a surface film explains why SH groups in the film react with ferricyanide whereas those in native egg albumin do not. In the native egg albumin molecule groups in the interior are inaccessible to certain reagents. A film is so thin that there are no inaccessible groups.

4. Because of the marked resemblance in the properties of egg albumin in surface films and of egg albumin after denaturation by the recognized denaturing agents, it may be supposed that the same fundamental change takes place in denaturation as in film formation—indeed, that film formation is one of the numerous examples of denaturation. This would mean that in general the SH groups of denatured egg albumin reduce ferricyanide and react with certain other reagents because they are no longer inaccessible to these reagents.
A PERFUSING SOLUTION FOR THE LOBSTER (HOMARUS) HEART AND THE EFFECTS OF ITS CONSTITUENT IONS ON THE HEART
Authors: Cole William H.
Published: May 2004

1. All inorganic perfusing solution for the heart of the lobster Homarus americanus, to allow prolonged normal beating (20 hours or more) must agree closely with the inorganic composition of the serum, which varies differentially with that of the environmental sea water.

2. All of the chief inorganic ions of the serum are necessary—Na, K, Ca, Mg, Cl, and SO4; the critical numbers of the ions being 100, 3, 5, 2–3, 116, and 1–2 respectively. Absence of Mg and SO4 will be tolerated for several hours.

3. The pH of the solution must agree with that of the serum within 0.2.

4. The osmotic pressure of the solution must agree with that of the serum within 15 per cent.

5. Beating of the heart will continue for several hours on improperly balanced solutions but changes in frequency, tone, or amplitude will occur. Hearts adapted to such solutions will show different responses to physical and chemical stimuli of the solution than those perfused on properly balanced solutions.

6. Arrest in systole is caused by isotonic NaCl, KCl, LiCl, and urea, and arrest in diastole by isotonic CaCl2, MgCl2, NaBr, NaI, MgSO4, and glucose.

7. Lithium cannot replace sodium; neither can bromide or iodide replace chloride ions.
THE EFFECT OF CALCIUM AND OTHER IONS ON THE AUTOCATALYTIC FORMATION OF TRYPSIN FROM TRYPSINOGEN
Authors: McDonald Margaret R. , Kunitz M.
Published: May 2004

Crystalline trypsinogen is completely transformed into trypsin by means of trypsin in the presence of calcium salts. The process follows the course of a pure autocatalytic unimolecular reaction.

In the absence of calcium salts, the autocatalytic formation of trypsin from trypsinogen is complicated by the transformation of part of the trypsinogen into an inert protein which cannot be changed into trypsin by any known means.

Salts increase or decrease the rate of both reactions so that the ultimate amount of trypsin formed varies with the nature and concentration of the salt used. With equivalent concentrations of salt the percentage of trypsinogen changed into trypsin is greatest in the presence of calcium ion followed in order by strontium; magnesium and sodium; rubidium, ammonium, lithium, and potassium; caesium and barium. With the anions the largest percentage of trypsinogen transformed into trypsin was found with the acetate, sulfate, oxalate, citrate, tartrate, fluoride, and chloride ions followed in order by bromide, nitrate, and iodide.

The formation of inert protein is completely suppressed by concentrations of calcium ion greater than 0.02 M.
OSMOTIC PROPERTIES OF THE EGG CELLS OF THE OYSTER (OSTREA VIRGINICA)
Authors: Lucké Balduin , Ricca R. A.
Published: May 2004

Investigations of the osmotic properties of oyster eggs by a diffraction method for measuring volumes have led to the following conclusions:

1. The product of cell volume and osmotic pressure is approximately constant, if allowance is made for osmotically inactive cell contents (law of Boyle-van't Hoff). The space occupied by osmotically inactive averages 44 per cent of cell volume.

2. Volume changes over a wide range of pressures are reversible, indicating that the semipermeability of the cell during such changes remains intact.

3. The kinetics of endosmosis and of exosmosis are described by the equation,

See PDF for Equation,

where dV is rate of volume change; S, surface area of cell, (P-Pe), the difference in osmotic pressure between cell interior and medium, and K, the permeability of the cell to water.

4. Permeability to water during endosmosis is 0.6µ3 of water per minute, per square micron of cell surface, per atmosphere of pressure. The value of permeability for exosmosis is closely the same; in this respect the egg cell of the oyster appears to be a more perfect osmometer than the other marine cells which have been studied. Permeability to water computed by the equation given above is in good agreement with computations by the entirely different method devised by Jacobs.

5. Permeability to diethylene glycol averages 27.2, and to glycerol 20.7. These values express the number of mols x 10–15 which enter per minute through each square micron of cell surface at a concentration difference of 1 mol per liter and a temperature of 22.5°C.

6. Values for permeability to water and to the solutes tested are considerably higher for the oyster egg than for other forms of marine eggs previously examined.

7. The oyster egg because of its high degree of permeability is a natural osmometer particularly suitable for the study of the less readily penetrating solutes.
THE EFFECT OF TEMPERATURE AND OF LYSIN CONCENTRATION ON THE ACCELERATION OF HEMOLYSIS
Authors: Ponder Eric
Published: May 2004

The acceleration of saponin hemolysis by benzene, indol, and nonyl alcohol has been investigated as a function of temperature, and it has been found that these accelerators have negative temperature coefficients. This points to their being concentrated at the cell surface, and to the surface being the seat of their accelerating action.

It is shown that the accelerating power of indol (used as a typical accelerator) is constant so long as the lysin in the system is capable of producing lysis per se, but that the acceleration falls off when only sublytic concentrations are present. The relations are expressed in a series of equations, and explained in terms of the reactions among the accelerator, the lysin, and the membrane component, which breaks down in spots, rather than uniformly, when lysis occurs. The argument involves a consideration of the idea that a monolayer of lysin at the cell surface is necessary for hemolysis, of Abramson's hypothesis of "key spots" on the surface, of the rate of escape of hemoglobin from the hemolyzing cell, and of the results of electrophoretic and impedance measurements. The existing theory of the kinetics is extended by introducing the idea of a variation in resistance from point to point in the cell membrane; in this form it describes the situation so far as is at present known, and shows that the results of the various methods of investigation are consistent with each other. The only idea discussed which seems to have little foundation is that lysis is determined by the formation of a monolayer of lysin at the cell surface; when this occurs, it must do so only as a special case. Finally, a semi-quantitative description of the frequency distribution of the resistances in the membrane is derived from existing data. The variation in resistance which it is necessary to assume is quite small, as might be expected in the case of a membrane with a regular ultra-structure.
P32 UPTAKE BY NUCLEI
Authors: Marshak A.
Published: May 2004

1. A method for isolating nuclei in quantity from mammalian tissues is described.

2. The rate of uptake of radioactive phosphorus by nuclei is found to be quite rapid. The phosphorus was shown not to be taken up by exchange.

3. Nuclei of tumors accumulate more radioactive phosphorus than normal liver nuclei. This was shown to be due to mitotic activity and not a form of metabolism peculiar to tumor cells.

4. The specific activities of nuclei and cytoplasm are compared.

5. 60 to 70 per cent of the nuclear radioactive phosphorus is present as nucleoprotein from 1 hour to 5 days after it is administered. In the lymphoma nuclei 90–95 per cent of the phosphorus is in the nucleoprotein fraction from 1–5 days after it is administered.

6. The specific activities of the nucleoprotein, lipid, and acid-soluble fractions of liver and tumor nuclei are compared.

7. From the rate of P32 uptake by nuclei it is calculated that a new lymphoma nucleus is synthesized on the average once every 27 hours. This is in agreement with the observed rate of growth of the tumor.

8. In the lymphoma nucleus it is calculated that 7 x 104 molecules of tetranucleotide are synthesized per second.

9. Irradiation with 200 r. x-rays alters the distribution of P32 in the lymphoma cell, markedly increasing the concentration in the nucleus shortly after irradiation. The P32 concentration in the cytoplasm decreases with time after irradiation. It is suggested that the altered distribution is correlated with the inhibition of mitosis produced by the x-rays.

10. Continual synthesis of nucleoprotein takes place even in nuclei of cells which do not undergo mitosis.
THE MAGNETIC BEHAVIOR OF CATALASE
Authors: Michaelis L. , Granick S.
Published: May 2004

The magnetic moment of catalase is 4.6 ± 0.3, nearly the same as that of ferric hemoglobin hydroxide. If the moment be due to electron spin alone without orbital contribution, 3 free electrons would give rise to 3.9 magnetons.
THE RADIOACTIVITY OF POTASSIUM FROM HUMAN SOURCES
Authors: Fenn W. O. , Bale William F. , Mullins Lorin J.
Published: May 2004

A comparison of the radioactivity of potassium from human and commercial sources indicates that the radioactive isotope K40 is probably 1 or 2 per cent less abundant in human potassium.
THE ACTIVITY OF YEAST INVERTASE AS A FUNCTION OF OXIDATION-REDUCTION POTENTIAL
Authors: Sizer Irwin W.
Published: May 2004

The activity of yeast invertase as a function of oxidation-reduction potential has been investigated using a large number of oxidants and reductants. The activity is constant over the range of Eh from –270 to +600 mv., but above Eh = +600 mv. there is a sharp decrease in activity reaching 0 at Eh = +1,000 mv. The inhibiting action of strong oxidants is upon the enzyme rather than on the substrate and appears to be essentially irreversible Experiments indicate that the inhibiting action of strong oxidants on invertase is primarily related to their high oxidation-reduction potential rather than to a specific toxic action unrelated to Eh. The effects of oxidation-reduction potential upon invertase activity are independent of the purity of the enzyme, since they are the same for commercial invertases, fresh bakers' yeast, powdered bakers' yeast, brewers' yeast, and highly purified invertase. Possible mechanisms involved in the inactivation of invertase by oxidants are discussed.
THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR
Authors: Sollner Karl , Carr Charles W. , Abrams Irving
Published: May 2004

1. Theoretical considerations lead to the conclusion that dissociable acidic groups present to a varying extent in different collodion preparations determine the electrochemical behavior of membranes cast from these preparations. It is further reasoned that the base exchange capacity of the collodion surfaces is the true quantitative measure of the abundance of the dissociable groups.

2. The concept of base exchange capacity and the base exchange method are discussed. The conditions which allow a purposeful application of the latter are stated.

3. The base exchange properties of a number of fibrous collodion preparations of different origins and after various types of treatment, having widely varying electrochemical activities, are determined.

4. With the chemical (titration) and physical (electrometric) methods employed, no regular correlation can be found between electrochemical activity and base exchange. The base exchange capacity which is necessary to cause even great electrochemical activity of collodion is extremely small.

5. Measurable to high base exchange capacity always seems to be associated with good or high electrochemical activity; but base exchange capacity too low to be definitely measurable with the available methods may be found with collodion preparations of high as well as with preparations of low electrochemical activity.

6. The bearing of these results upon the problem of the spatial and electrical structure of the collodion membrane is indicated briefly.
STIMULATION OF CELLS BY INTENSE FLASHES OF ULTRAVIOLET LIGHT
Authors: Harvey E. Newton
Published: May 2004

A study has been made of the effect of sudden intense flashes of ultraviolet light, acting on a wide variety of cells and tissues, with special reference to stimulation.

The flashes are obtained by a high voltage condenser discharge through a quartz mercury vapor sterilamp, using the method of Rentschler. The lethal effect of a single such discharge is widespread among unicellular organisms.

Medullated nerves and whole muscles are not visibly stimulated, because of absorption by connective tissue. Single muscle fibers undergo immediate contracture in 50 per cent of the experiments.

Nitella cells are stimulated, the effect depending on the dosage. Weak ultraviolet flashes slow or stop cyclosis reversibly. Strong flashes stop cyclosis reversibly with the appearance of a local or a propagated action potential. Very strong flashes kill the Nitella cells.

The effect of single flashes on myonemes, oscillatory movement, ameboid movement, cilia, flagella, and bioluminescence is described in the text.
PURIFICATION AND CRYSTALLIZATION OF DIPHTHERIA ANTITOXIN
Authors: Northrop John H.
Published: May 2004

Purified preparations of diphtheria antitoxin have been obtained by digestion of the toxin-antitoxin complex with trypsin, followed by fractional precipitation with ammonium sulfate. The various fractions obtained in this way are all 90 per cent or more precipitated by diphtheria toxin but combine with different quantities of the toxin.

The fraction precipitated between 0.33 and 0.5 saturated ammonium sulfate is homogeneous by electrophoresis and ultracentrifuge but does not have constant solubility.

A small amount of a more soluble fraction has been obtained which does have constant solubility and satisfies the criteria of a pure protein. This protein crystallizes readily in poorly formed thin plates. It is very unstable and reverts to a less soluble non-crystallizable form. It has a sedimentation constant of 5.7 x 10–13 and a molecular weight of 90,500. It has an antitoxic value of 700–900 flocculation units per mg. protein nitrogen and has an antitoxic value by the protection test of about 700 units per mg. protein nitrogen.

The precipitation range of the purified antitoxin with purified toxin is much wider than that with crude preparations.
PURIFIED DIPHTHERIA ANTITOXIN IN THE ULTRACENTRIFUGE AND IN THE ELECTROPHORESIS APPARATUS
Authors: Rothen Alexandre
Published: May 2004

Ultracentrifugation studies of diphtheria antitoxin showed that:

1. Purified antitoxin of high activity obtained from horse plasma without enzymatic treatment has exactly the same sedimentation constant as the globulin fraction obtained in a similar way from normal horse plasma s20water = 6.9 x 10–13.

2. Purified antitoxin obtained with trypsin digestion of the toxin-antitoxin complex has a sedimentation constant of s20water = 5.5 ± 0.1 x 10–13, a diffusion constant of D20water = 5.76 x 10–7, and a molecular weight of about 90,000.

Electrophoresis experiments demonstrated that:

1. The trypsin-purified antitoxin has an isoelectric point not far from pH 7.0.

2. The reversible spreading noticed at about pH 7.3 cannot be attributed to heterogeneous preparation.

3. The large increase in the γ-globulin fraction occurring during immunization consists either of antitoxin of various degrees of activity or of some inert protein in addition to the antitoxin.
QUANTITATIVE CHEMICAL STUDIES ON HEMOLYSINS
Authors: Heidelberger Michael , Treffers Henry P.
Published: May 2004

1. Total antibody in hemolysins may be estimated from the nitrogen added to sheep stromata suspensions.

2. The method is applied to a number of hemolysins and a correlation, valid to within 20 per cent, established between hemolytic titer and total antibody.

3. When stromata combine with antibody in the presence of guinea pig complement they may take up at least 80 per cent of their weight of complement combining component(s).
THE MECHANISMS OF X-RAY EFFECTS ON CELLS
Authors: Sax Karl
Published: May 2004

Irradiation of Tradescantia microspores does not increase subsequent sensitivity to x-rays as measured by the frequency of induced chromosomal aberrations curing the nuclear cycle. The slight decrease in sensitivity is to be expected because acentric fragments are less sensitive than the centric chromosomes. The physiological effects of x-rays appear to be of minor importance in causing injury or death of individual cells, and most of the deleterious effects can be attributed to "direct hits" which produce chromosomal alterations. In the reaction of tissues to x-rays the physiological effects may play a more important part.
CERTAIN ENZYMATIC ACTIVITIES OF NORMAL AND MOSAIC INFECTED TOBACCO PLANTS
Authors: Wynd F. Lyle
Published: May 2004

The lower leaves of tobacco plants were inoculated with leaf mosaic virus and the activities of oxygenase, peroxidase, catalase, and invertase were followed in leaves of comparable age at intervals of 2 or 3 days over a period of 21 days.

The inoculated leaves exhibited a great decrease relative to normal tissue in the activity of oxygenase and peroxidase on the 6th day. Younger leaves showed this minimum at a progressively later date. A great decrease in the activities of these enzymes was attained by the 14th to the 18th day. This maximum was followed by a decrease.

Catalase exhibited an increased activity which reached a maximum at about the 8th day. A second maximum was observed on the 16th to the 18th day.

Invertase reached a minimum, relative to normal plants, on about the 8th day. A second minimum was approached on the 16th to the 18th day.

These data show that profound disturbances in the physiology of infected plants occur many days before the leaf juice attains an infectious concentration of virus. The observed activities could not be due therefore to metabolic activities of the virus particles themselves.

Since infectivity is attained only after a period of profound physiological disturbance, it seems possible that the virus protein develops as a product of abnormal metabolism.
THE METABOLISM OF TISSUE CULTURES
Authors: Wilson Hildegard , Jackson Elizabeth B. , Brues Austin M.
Published: May 2004

1. The metabolism of chick embryo tissues has been followed by analysis of the culture media after various periods of incubation in roller bottles.

2. The initial rate of glucose utilization is increased by increasing glucose in the medium from 100 to 500 mg. per cent. Total glucose used can be increased in the same way or by daily addition of small amounts. Glucose is used in greatest amount when the medium containing 100 mg. per cent is replaced daily.

3. Although glucose consumption appears necessary for survival of cultures it may be used at a rate far in excess of that required for life and maximal growth. Complete blocking of mitosis by colchicine does not alter the rate of glucose utilization.

4. Proteolytic activity of the cultures is shown by an increase in the amino nitrogen of the peptone medium after incubation with tissue.

5. Utilization of nitrogen from an amino acid medium is shown by a decrease in the amino nitrogen of this medium. Cells obtaining their nitrogen from amino acids proliferate as rapidly as those grown in a medium identical except for the substitution of peptone, but the cell type is markedly different, in that embryo muscle forms cells resembling regenerating adult muscle.

6. Lactic acid was formed in both the presence and absence of glucose. Its formation increased with increased glucose utilization. There is some evidence that lactate may be utilized, and that it favors growth in the absence of glucose.

7. Added pyruvate was rapidly metabolized by the tissues. It, too, favors growth slightly in the absence of glucose.
PANTOTHENIC ACID AND THE UTILIZATION OF GLUCOSE BY LIVING AND CELL-FREE SYSTEMS
Authors: Teague Peyton C. , Williams Roger J.
Published: May 2004

1. Added pantothenic acid was found to have no appreciable effect on the fermentation of glucose when used in conjunction with preparations of dialyzed yeast maceration juice or acetone-precipitated yeast maceration juice.

2. Addition of pantothenic acid failed to affect the rate of phosphorylation of glucose or the rate of decarboxylation of pyruvic acid by yeast maceration juice.

3. Pantothenic acid showed no effect on the rate of glycolysis by homogenized deficient chick tissues.

4. The accelerating effect of pantothenic acid on fermentation by deficient yeast cells was found to be accompanied by a "binding" of pantothenic acid by the yeast cells.
THE VALENCE OF CORPUSCULAR PROTEINS
Authors: Gorin Manuel H. , Mover Laurence S.
Published: May 2004

By the use of two extreme models: a hydrated sphere and an unhydrated rod the valence (net charge) of corpuscular proteins can be successfully calculated from electric mobility data by the Debye-Hückel theory (modified to include the effect of the ions in the ion atmosphere) in conjunction with the electrophoretic theory of Henry. As pointed out by Abramson, this permits a comparison with values for the valence from titration data.

Electrometric titration measurements of serum albumin B (Kekwick) have been determined at several ionic strengths. These results, together with the available data in the literature for serum albumin B, egg albumin, and ß-lactoglobulin have been used to compare values for the valence calculated from measurements of titration, electrophoresis, and membrane potentials. The results indicate that the usual interpretation of titration curves is open to serious question. By extrapolation of the titration data to zero ionic strength and protein concentration, there results an "intrinsic" net charge curve describing the binding of H+ (OH-) ion alone. This curve agrees closely, in each case, with values of the valence calculated from mobility data (which in turn are in close accord with those estimated from membrane potential measurements). The experimental titration curves in the presence of appreciable quantities of ions and protein deviate widely from the ideal curve. It is suggested that, under these conditions, binding of undissociated acid (base) leads to erroneous values for the net charge. This binding would not affect the electrophoretic mobility.

Values of the net charge obtained by the two extreme models from electrophoretic data are in agreement within 15 to 20 per cent. The agreement between the cylindrical model and the titration data is somewhat better in each case than with the sphere; i.e., this comparison enables a choice to be made between asymmetry and hydration in the interpretation of results from sedimentation and diffusion measurements on proteins. It is concluded that the proteins discussed here are somewhat asymmetric and also hydrated.
ENERGY, QUANTA, AND VISION
Authors: Hecht Selig , Shlaer Simon , Pirenne Maurice Henri
Published: May 2004

1. Direct measurements of the minimum energy required for threshold vision under optimal physiological conditions yield values between 2.1 and 5.7 x 10–10 ergs at the cornea, which correspond to between 54 and 148 quanta of blue-green light.

2. These values are at the cornea. To yield physiologically significant data they must be corrected for corneal reflection, which is 4 per cent; for ocular media absorption, which is almost precisely 50 per cent; and for retinal transmission, which is at least 80 per cent. Retinal transmission is derived from previous direct measurements and from new comparisons between the percentage absorption spectrum of visual purple with the dim-vision luminosity function. With these three corrections, the range of 54 to 148 quanta at the cornea becomes as an upper limit 5 to 14 quanta actually absorbed by the retinal rods.

3. This small number of quanta, in comparison with the large number of rods (500) involved, precludes any significant two quantum absorptions per rod, and means that in order to produce a visual effect, one quantum must be absorbed by each of 5 to 14 rods in the retina.

4. Because this number of individual events is so small, it may be derived from an independent statistical study of the relation between the intensity of a light flash and the frequency with which it is seen. Such experiments give values of 5 to 8 for the number of critical events involved at the threshold of vision. Biological variation does not alter these numbers essentially, and the agreement between the values measured directly and those derived from statistical considerations is therefore significant.

5. The results clarify the nature of the fluctuations shown by an organism in response to a stimulus. The general assumption has been that the stimulus is constant and the organism variable. The present considerations show, however, that at the threshold it is the stimulus which is variable, and that the properties of its variation determine the fluctuations found between response and stimulus.
RESPIRATORY EFFECTS UPON THE VISUAL THRESHOLD
Authors: Wald George , Harper P. V. , Goodman H. C. , Krieger H. P.
Published: May 2004

Measurements are reported of the effects of respiratory stresses upon the absolute threshold of peripheral (rod) vision. Since subjects were kept wholly dark adapted and the photochemical system of the rods therefore stationary, the changes recorded may be assumed to have originated more centrally. To this degree the measurements provide a quantitative index of central nervous imbalance.

Breathing room air or 32 to 36 per cent oxygen at about double the normal rate causes the visual threshold to fall to approximately half the normal value within 5 to 10 minutes.

This change is due primarily to alkalosis induced by the hyperventilation, and can be abolished or reversed by adding carbon dioxide to the inspired mixtures. Normal or rapid breathing of 2 per cent carbon dioxide causes no change in threshold; with 5 per cent carbon dioxide the threshold is approximately doubled.

Breathing 10 per cent oxygen at the normal rate also approximately doubles the threshold. This effect is compensated in part by rapid breathing. When 10 per cent oxygen is breathed at twice the normal rate the threshold usually falls at first, then slowly rises to supernormal levels.

Due primarily to variations in their breathing patterns subjects yield characteristically different responses on sudden exposure to low oxygen tensions with breathing uncontrolled. The threshold may either rise or fall; and on release from anoxia it may rise, or fall to normal or subnormal levels. The threshold adjusts to anoxia rapidly; exposures lasting 5 to 6 hours do not produce greater or more persistent changes than those of much shorter duration.
THE REGENERATION OF VISUAL PURPLE IN THE LIVING ANIMAL
Authors: Peskin James C.
Published: May 2004

1. The accumulation of visual purple in the retina after bleaching by light has been studied in the intact eye of the frog. The data show that duration and intensity of light adaptation, which influence the course of human dark adaptation as measured in terms of visual threshold, have a similar influence on the course of visual purple regeneration.

2. At 25°C. frogs which have been light adapted to 1700 millilamberts and then placed in the dark, show an increase in visual purple concentration which begins immediately and continues for 70 minutes until a maximum concentration is attained. The increase, although beginning at once, is slow at first, then proceeds rapidly, and finally slows up towards the end. Frogs which have been adapted to 9500 millilamberts show essentially the same phenomenon except that the initial slow period is strongly delayed so that almost no visual purple is formed in the first 10 minutes.

3. At 15°C. the initial delay in visual purple regeneration occurs following light adaptation to both 1700 and 9500 millilamberts. The delay is about 10 minutes and is slightly longer following the higher light adaptation.

4. The entire course of visual purple accumulation in the dark takes longer at the lower temperature than at the higher. The temperature coefficient for 10°C. is about 1.8.

5. In contrast to the behavior of the isolated retina which has small amounts of vitamin A and large amounts of retinene immediately after exposure to light, the intact eye has large amounts of vitamin A and little retinene after exposure to light for 10 minutes. In the intact eye during dark adaptation, the amount of vitamin A decreases markedly while retinene decreases only slightly in amount. If retinene is formed in the intact eye, the change from retinene to vitamin A must therefore occur rapidly in contrast to the slow change in the isolated retina.

6. The course of visual purple regeneration may be described by the equation for a first order autocatalyzed reaction. This supposes that the regeneration of visual purple is catalyzed by visual purple itself and accounts for the sigmoid shape of the data.
INCREASED IRRITABILITY IN NITELLA DUE TO GUANIDINE
Authors: Osterhout W. J. V.
Published: May 2004

Guanidine applied to Nitella may lower the threshold of E.M.F. required to produce electrical stimulation and may give rise to trains of action currents. Its effect thus appears to be somewhat similar to that observed in animals.

Rapid action currents are produced as well as "square topped" action curves and transitional forms.

These effects may be due in part to increased protoplasmic conductivity produced by the penetration of guanidine.
FURTHER CHEMICAL STUDIES ON BLOOD-AQUEOUS HUMOR DYNAMICS
Authors: Kinsey V. Everett , Grant W. Morton
Published: May 2004

The proportion of SCN, Br, PO4, urea, levulose, and Fe which remains freely diffusible when added to plasma has been determined by ultrafiltration and "differential" dialysis through a cellophane membrane. After injecting each of these substances as well as Mg and Li into rabbits a continuous record of their concentration in the plasma was obtained for each animal and the concentration in the aqueous humor was also determined and related to the maximum diffusible concentration in the plasma.
THE MECHANISM OF AQUEOUS HUMOR FORMATION INFERRED FROM CHEMICAL STUDIES ON BLOOD-AQUEOUS HUMOR DYNAMICS
Authors: Kinsey V. Everett , Grant W. Morton
Published: May 2004

The importance of considering the effect of a possible flow out of the anterior chamber before inferring any mechanism of aqueous humor formation from the relative concentration of a substance in the aqueous humor and plasma under equilibrium conditions has been stressed.

Several processes to account for the chemical equilibria between aqueous humor and blood based on the ultrafiltration and secretion hypotheses with a possible simultaneous loss of aqueous humor by flow have been outlined. On the basis of these processes, equations were formulated which would relate the rates of transfer into and out of the anterior chamber to the ratio of concentration of a substance in the aqueous to that in the blood at various intervals after its introduction into the blood. The explanation of equilibrium ratios above and below one for aqueous constituents is made apparent from the mathematical formulations. For each substance tested a determination was made of the best fit when the concentration in the aqueous humor is plotted against time. This fit was obtained by plotting the rate of transfer in against the rate of transfer out of the anterior chamber for all of the experimentally found concentration ratios on the basis of both the ultrafiltration and secretory hypotheses. Two sets of values were obtained from these calculations, one set for each hypothesis.

The substantial agreement of all the experimental data with an assumed rate of leakage out of the anterior chamber of approximately 4 c. mm. per minute was shown to be compatible only with the idea that all the monovalent electrolytes tested entered the anterior chamber as a result of secretory process. It could not be decided from these chemical studies whether the non-electrolytes and the one multivalent electrolyte tested enter the anterior chamber by ultrafiltration or secretion.

Experimental findings from other sources were cited which would suggest that non-electrolytes enter the anterior chamber as a result of ultrafiltration.

The implications of the mechanism outlined in the paper with respect to intraocular pressure have been discussed.

Supplementary evidence from the literature has been given in support of the conclusions presented here.
A NEW METHOD FOR THE GENERATION AND USE OF FOCUSED ULTRASOUND IN EXPERIMENTAL BIOLOGY
Authors: Lynn John G. , Zwemer Raymund L. , Chick Arthur J. , Miller August E.
Published: May 2004

1. An efficient generator of focused ultrasound has been designed, built, and successfully operated.

2. The generator has been used to produce focal heating in the centers of paraffin blocks, and in a similar manner, focal areas of destruction were obtained deep in fresh liver tissue with minimal effects at the surface and no effects on the intervening tissue.

3. In animals, focused ultrasound of high intensity produced local cerebral changes as inferred from behavior disabilities and as demonstrated at autopsy. This local brain effect was achieved through intervening scalp, skull, and meninges. The resulting behavior disabilities disappeared in from 2 to 16 hours.

4. To date, it has not been possible to produce such brain changes without incidental injury to the skin and subcutaneous tissue lying at the base of the cone of radiation.

5. Improvements in generation and application of the focused supersonic beam are suggested whereby it should be possible to increase still further the focal effects in the brain, with a corresponding decrease or elimination of complicating surface injury.
REDUCTION OF CARBON DIOXIDE COUPLED WITH THE OXYHYDROGEN REACTION IN ALGAE
Authors: Gaffron Hans
Published: May 2004

1. Unicellular algae possessing a hydrogenase system (Scenedesmus and other species), and having been adapted by anaerobic incubation to the hydrogen metabolism, reduce oxygen to water according to the equation O2 + 2H2 → 2H2O.

2. The oxyhydrogen reaction proceeds undisturbed only in the presence of carbon dioxide, which simultaneously is reduced according to the equation CO2 + 2H2 → H2O + (CH2O) = (carbohydrate).

3. The maximum yield of the induced reduction is one-half molecule of carbon dioxide reduced for each molecule of oxygen absorbed.

4. Partial reactions are recognizable in the course of the formation of water and it is with the absorption of the second equivalent of hydrogen that the carbon dioxide reduction appears to be coupled.

5. The velocity of the reaction increases in proportion to the partial pressure of oxygen, but only up to a certain point where any excess of oxygen causes the inactivation of the hydrogenase system. The reaction then ends prematurely.

6. During the oxyhydrogen reaction little or no oxygen is consumed for normal respiratory processes.

7. Small concentrations of cyanide, affecting neither photosynthesis nor photoreduction in the same cells, first inhibit the induced reduction of carbon dioxide and then lead to a complete inactivation of the hydrogenase system.

8. Hydroxylamine, added after adaptation, has either no inhibitory effect at all, or prevents solely the induced reduction of carbon dioxide without inactivating the hydrogenase system.

9. Dinitrophenol prevents the dark reduction of carbon dioxide while the reduction of oxygen continues to the formation of water.

10. Glucose diminishes the absorption of hydrogen, probably in its capacity as a competing hydrogen donor.

11. The induced reduction of carbon dioxide can be described as an oxido-reduction similar to that produced photochemically in the same cells.
TYROSINASE AND PLANT RESPIRATION
Authors: Baker Dwight , Nelson J. M.
Published: May 2004

The evidence presented in this paper supports the conclusion that at least 85 per cent of the oxygen uptake of the respiring tissue of potato tuber enters the chemistry of the cell by way of a tyrosinase-catalyzed oxidation.

The qualitative aspects of this conclusion are in agreement with the claim made by Boswell and Whiting. However, the evidence offered by them in support of this conclusion is shown to be inadequate.
THE ELECTRICAL CONDUCTIVITY OF SODIUM AND POTASSIUM GUAIACOLATES IN GUAIACOL
Authors: Shedlovsky Theodore
Published: May 2004

The data of the author and Uhlig, and new data, on the conductivity of sodium and of potassium guaiacolates in guaiacol at 25° have been computed with an improved conductance equation which is valid to somewhat higher concentrations than the equations formerly used.

The new constants are, Λ0 = 9.0, K = 2.8 x 10–5 for sodium guaiacolate and Λ0 = 9.5, K = 3.4 x 10–5 for potassium guaiacolate.