bluuebunny/crossref_metadata_2025 huggingface dataset:
TIME-TEMPERATURE RELATIONS IN THE INCUBATION OF THE WHITEFISH, COREGONUS CLUPEAFORMIS (MITCHILL)
Authors: Price John W.
Published: May 2004

1. Whitefish eggs incubated in aerated lake water at controlled tempera tures of 0°, 0.5°, 2°, 4°, 6°, 8°, 10°, and 12°C., failed to hatch at either 0° or 12°C. 0.6 per cent hatched alive at 10°C., 72.67 per cent hatched alive at 0.5°C., and an intermediate proportion hatched at intermediate temperatures.

2. The percentage of abnormal embryos which developed to the hatching stage varied directly with temperature between 4° and 12°, all embryos being abnormal at 12°C.; but none were abnormal at either 0.5°, or 2°C. Normal development predominated from 0.5 to 6°C. The highest proportion of embryos to hatch alive was 72.67 per cent at 0.5°C., which is, hence, the optimum temperature.

3. Total incubation time ranged from 29.6 days at 10°C. to 141 days at 0.5°C.

4. The time (T) required to attain any given stage of development is expressed in equations

See PDF for Equation

where temperature, t, is a negative exponent of the constant, A, whose value differs above or below 6°C., a critical temperature. Values of A above 6° fluctuate about 1.13; those of A below 6° fluctuate about 1.19 as a mean.

5. Applying Arrhenius' equation µ values for the total incubation period are 27,500 below 6° and 27,100 above it.

6. The relative magnitude of A values of the exponential equation and µ values of Arrhenius' equation show corresponding changes from one developmental period to another.

7. When plotted, thermal increments show cyclic variations, with maxima during periods of cleavage and of organogenesis. These may indicate the interaction of two separate sets of embryonic processes, which give a maximal response to temperature differences during these two separate periods.

8. Above 6°, µ values during the hatching process are distinct from those of developmental stages and are regarded as being due to the action of hatching enzymes.
BIOELECTRIC POTENTIALS IN HALICYSTIS
Authors: Blinks L. R.
Published: May 2004

The effects of light upon the potential difference across the protoplasm of impaled Halicystis cells are described. These effects are very slight upon the normal P.D., increasing it 3 or 4 per cent, or at most 10 per cent, with a characteristic cusped time course, and a corresponding decrease on darkening.

Light effects become much greater when the P.D. has been decreased by low O2 content of the sea water; light restores the P.D. in much the same time course as aeration, and doubtless acts by the photosynthetic production of O2. There are in both cases anomalous cusps which decrease the P.D. before it rises. Short light exposures may give only this anomaly. Over part of the potential range the light effects are dependent upon intensity.

Increased CO2 content of the sea water likewise depresses the P.D. in the dark, and light overcomes this depression if it is not carried too far. Recovery is probably due to photosynthetic consumption of CO2, unless there is too much present. Again there are anomalous cusps during the first moments of illumination, and these may be the only effect if the P.D. is too low.

The presence of ammonium salts in the sea water markedly sensitizes the cells to light. Subthreshold NH4 concentrations in the dark become effective in the light, and the P.D. reverses to a negative sign on illumination, recovering again in the dark. This is due to increase of pH outside the cell as CO2 is photosynthetically reduced, with increase of undissociated NH3 which penetrates the cell.

Anomalous cusps which first carry the P.D. in the opposite direction to the later drift are very marked in the presence of ammonia, and may represent an increased acidity which precedes the alkaline drift of photosynthesis. This acid gush seems to be primarily within the protoplasm, persisting when the sea water is buffered. Glass electrode measurements also indicate anomalies in the pH drift.

There are contrary cusps on darkening which suggest temporarily increased alkalinity.

Even more complex time courses are given by combining low O2 and NH4 exposures with light; these may have three or more cusps, with reversal, recovery, and new reversal.

The ultimate cause of the light effects is to be found in an alteration of the surface properties by the treatments, which is overcome (low O2, high CO2), or aided (NH4) by light. This alteration causes the surface to lose much of its ionic discrimination, and increases its electrical resistance. Tests with various anion substitutions indicate this, with recovery of normal response in the light.

A theory of the P.D. in Halicystis is proposed, based on low mobility of the organic anions of the protoplasm, with differences in the two surfaces with respect to these, and the more mobile Na and K. ions.
EFFECTS OF HEXYLRESORCINOL ON NITELLA
Authors: Osterhout W. J. V.
Published: May 2004

In some ways the effects of hexylresorcinol on Nitella resemble those of guaiacol but in others they differ.

Both substances depress the P.D. reversibly and both decrease the potassium effect.

Hexylresorcinol decreases the apparent mobility of Na+ and of K+. Guaiacol increases that of Na+ but not of K+.

The action of hexylresorcinol is more striking than that of guaiacol since 0.0003 M of the former is as effective as 0.03 M of the latter in depressing the P.D.

It is evident that organic substances can change the behavior of inorganic ions in a variety of ways.
THE RELATION BETWEEN FOVEAL VISUAL ACUITY AND ILLUMINATION UNDER REDUCED OXYGEN TENSION
Authors: McFarland R. A. , Halperin M. H.
Published: May 2004

1. The foveal visual acuity of eleven subjects was studied in relation to illumination under normal atmospheric conditions and at simulated altitudes of 10,000 feet (14.3 per cent O2) and 18,000 feet (10.3 per cent O2). A mask was used to administer the desired mixtures of oxygen and nitrogen. At the end of each experiment, measurements were made while inhaling 100 per cent oxygen from a cylinder. A red filter (No. 70 Wratten) was used so as to study only the behavior of the cones of the retina.

2. The logarithm of illumination was plotted horizontally (abscissa) and the logarithm of visual acuity vertically (ordinate). The reduced oxygen tensions resulted in a shift of the curve to the right, along the intensity axis, the extent of the change being 0.24 of a log unit at 14.3 per cent O2 and 0.47 of a log unit at 10.3 per cent O2. These effects were completely counteracted within a few minutes by inhaling oxygen.

3. As a consequence of the shape of the curve, such a shift to the right resulted in a relatively large decrease of visual acuity at low illuminations. At increasing light intensities anoxia produced less and less change, until at very high illuminations the decrease was negligible. Thus with 10.34 per cent O2 the visual acuity at 0.144 photons decreased an average of 0.344 of a log unit, to 45 per cent of its normal value. At 1320 photons, however, it decreased only 0.026 of a log unit, to 94 per cent of its normal value for that intensity.
THE PURIFICATION OF CATHEPSIN
Authors: Anson M. L.
Published: May 2004

1. One mg. of the purified cathepsin whose preparation is described is as active as the extract of 1.3 gm. of spleen. An eightfold further purification is possible by procedures which are still being modified and so are not described in the present paper.

2. The first step of the purification consists in suspending frozen and thawed spleen in water and letting it autolyze.

3. In the second step, ammonium sulfate is added and the suspension is acidified and warmed. Much additional autolysis takes place. The cathepsin is protected from destruction by being adsorbed to the insoluble spleen material. When this insoluble material is filtered off most of the products of autolysis remain in the filtrate.

4. The cathepsin is then released from the insoluble spleen material by making the suspension slightly alkaline. Some inert protein still remains adsorbed to the insoluble spleen material.

5. More inert protein is removed by adsorption with aluminum hydroxide formed in the cathepsin solution by the addition first of aluminum chloride and then of sodium hydroxide. Preformed aluminum hydroxide is a much less effective adsorbent.

6. The purified cathepsin is precipitated from very dilute solution with tungstic acid. Tungstic acid precipitates most proteins in the native form provided the solution is not too acid.

7. Further evidence is given that cathepsin is not a proteinase of the papain type.
THE PHOTODYNAMIC INACTIVATION OF PHAGE PRECURSOR BY METHYLENE BLUE
Authors: Krueger A. P. , Scribner E. J. , Mecracken T.
Published: May 2004

Methylene blue added to suspensions of activated staphylococci in amounts sufficient to furnish 1 x 105 molecules of dye/bacterium inactivates the phage precursor content of the cells without causing cell death when the mixtures are exposed to strong light of 4000–8000 Å. There is a lag phase of approximately 15 minutes in the photodynamic inactivation of phage precursor by methylene blue. This delay seems to be due to a primary reaction between the cell and methylene blue after the completion of which exposure to light brings about the inactivation of precursor quite promptly.
ACTION CURVES WITH SINGLE PEAKS IN NITELLA IN RELATION TO THE MOVEMENT OF POTASSIUM
Authors: Osterhout W. J. V. , Hill S. E.
Published: May 2004

In Nitella the action curve has two peaks, apparently because both protoplasmic surfaces (inner and outer) are sensitive to K+.

Leaching in distilled water makes the outer surface insensitive to K+. We may therefore expect the action curve to have only one peak. This expectation is realized.

The action curve thus obtained resembles that of Chara which has an outer protoplasmic surface that is normally insensitive to K+.

The facts indicate that the movement of K+ plays an important part in determining the shape of the action curve.
EFFECTS OF GUAIACOL AND HEXYLRESORCINOL IN THE PRESENCE OF BARIUM AND CALCIUM
Authors: Osterhout W. J. V.
Published: May 2004

Guaiacol was applied at two spots on the same cell of Nitella. At one spot it was dissolved in 0.01 M NaCl, at the other in 0.01 M CaCl2 or BaCl2. The effect was practically the same in all cases, i.e. a similar change of P.D. in a negative direction, involving a more or less complete loss of P.D. (depolarization).

When hexylresorcinol was used in place of guaiacol the result was similar. That Ca++ and Ba++ do not inhibit the effect of these organic depolarizing substances may be due to a lack of penetration of Ca++ and Ba++. The organic substances penetrate more rapidly and their effect is chiefly on the inner protoplasmic surface which is the principal seat of the P.D.
A NEW FORM OF DIFFERENTIAL MICRORESPIROMETER
Authors: Cunningham Burris , Kirk Paul L.
Published: May 2004

1. A microrespirometer suitable for measuring oxygen uptakes from 0.1 to 10λ per hour is described.

2. The sensitivity of the instrument may be readily altered by substituting different sizes of capillary tubing.

3. By means of replaceable brass plugs the chamber volume of this instrument may be varied from 700 to less than 40λ.

4. No thermostat is required for the operation of the instrument at room temperature.

5. It may be charged at one temperature and used at a widely different one.

6. The chambers may be filled with any desired gas mixture.

7. Two solutions may be mixed during the course of an experiment.

8. The entire apparatus may be sterilized.
THE UPTAKE OF INORGANIC ELECTROLYTES BY THE CRAYFISH
Authors: Maluf N. S. Rustum
Published: May 2004

1. Reasons are given for believing that the uptake of Na+, Cl-, and NaCl by the crayfish occurs through the gills.

2. A crayfish in fresh water, with a Cl concentration of about 0.2 mEq./l., can) by active Cl absorption, compensate entirely for Cl lost in the urine.

3. The carbonic anhydrase activity of the gills is markedly higher than that of other tissues of the crayfish, but the equivalent CO2 output of the crayfish is far in excess of the equivalent Cl absorption per unit time and weight and thus fails to warrant the supposition that Cl absorption is of respiratory importance.

4. The carbonic anhydrase activity of the soft integument of the lobster, before and after molting, and of the hypodermis of the hard-cuticled animal is almost identical and of the same order as that of other tissues of the lobster.

5. The concentration of the electrolytes was about 7.5 mEq./l.; i.e., considerably lower than in the blood of the crayfish. Cl- can be taken up independently of the complementary cation. Na+ can be taken up independently of the complementary anion. K+ and SO4= are not taken up at all. In pure NaCl, the Na+ and Cl- are absorbed evidently largely together. Ca++ is absorbed only in newly molted animals and in animals preparing to molt but is not absorbed by hard-cuticled animals not preparing to molt. Ca++ is taken up independently of Cl- in pure CaCl2.

6. Newly molted animals absorb Ca++ at a rate exceeding that of the absorption of other absorbable ions (Na+ and Cl-) in the same equivalent concentration.

7. A crayfish utilizes the Ca++ in fresh water in the calcification of its cuticle. Since the animal does not swallow water, the Ca++ must enter through the exterior. Reasons are given for believing that, unlike Na+ and Cl-, Ca++ is absorbed directly from the exterior by the integument and does not enter the body through the gills.

8. During molting, only about 4 per cent of the raw ash and 2.3 per cent of the organic material of the old cuticle is resorbed.
MOLECULAR WEIGHT AND ELECTROPHORESIS OF CRYSTALLINE RIBONUCLEASE
Authors: Rothen Alexandre
Published: May 2004

Electrophoretic studies on purified crystalline ribonuclease showed the absence of any impurities differing in mobility from the bulk of material.

The isoelectric point of ribonuclease was found by electrophoresis to be at about pH 7.8.

Ultracentrifuge studies indicated fair homogeneity of ribonuclease in solution. Only one moving component has been observed.

The molecular weight of ribonuclease was found to be 12,700 from rate of sedimentation (S25 = 1.85 x 10–13 in 0.5 M (NH4)2SO4) and diffusion measurement (D = 1.36 x 10–6 in 0.5 M (NH4)2SO4), in good agreement with the average value of 13,000 found from equilibrium measurements. This low value for the molecular weight of a protein would seem to discredit the value 17,600 as representing a universal unit weight for proteins in general.
STUDIES ON PITUITARY LACTOGENIC HORMONE
Authors: Li Choh Hao , Lyons William R. , Evans Herbert M.
Published: May 2004

The solubility of sheep pituitary lactogenic hormone in 0.302 M NaCl at pH 2.02 (solution in HCl) has been determined at room temperature. It showed a constant solubility in the presence of a considerable excess of the solid phase, an indication that the preparation contained but one component.

Beef lactogenic hormone showed a constant solubility in distilled H2O at 7–8°C in the presence of excess of the solid phase.

The salting-out effect of NaCl in acid solution of both beef and sheep hormones has been studied at room temperature. In these studies both preparations behaved as pure substances, but they exhibited differences in solubility, thus indicating a species specificity.
EFFECTS OF HEXYLRESORCINOL ON VALONIA
Authors: Osterhout W. J. V.
Published: May 2004

The effects on Valonia of guaiacol and hexylresorcinol are similar but the latter is more effective.

Both substances lower or abolish the potassium effect; i.e., the ability of the cell to distinguish electrically between Na+ and K+.

Both substances change the order of mobilities so that vCl > uNa becomes uNa > vCl or uNa = vCl.
THE FLICKER RESPONSE CONTOUR FOR PHRYNOSOMA (HORNED LIZARD; CONE RETINA)
Authors: Crozier W. J. , Wolf Ernst
Published: May 2004

The lizard Phrynosoma, with purely cone retina, provides a simplex flicker response contour (log critical flash intensity as a function of flash frequency). It is well described as a normal probability integral (F - log I).

The Phrynosoma curve differs markedly, in higher slope and in higher median intensity level, from that obtained under the same conditions for the turtle Pseudemys, also with entirely cone retina. Other comparisons having a bearing on the duplexity doctrine are discussed.
CHEMICAL PACEMAKERS
Authors: Hadidian Zareh , Hoagland Hudson
Published: May 2004

1. In a previous paper it was found that 11,200 calories is obtained for the energy of activation in the oxidation of succinate to fumarate in the presence of crude beef heart extract when succino-dehydrogenase was made the limiting factor. 16,000 calories was obtained with this preparation when cytochrome-cytochrome oxidase was made the limiting factor. In the present paper activation energies of the components of this enzyme system are further studied.

2. Oxidation of p-phenylenediamine catalyzed by the extract and known not to involve the dehydrogenase component yields Arrhenius equation plots indicating a pacemaker reaction with a µ of 9,500 calories.

3. An activation energy of 17,500 calories is obtained for the oxidation of succinate to fumarate in the presence of the beef heart extract partially poisoned by pyrophosphate. Evidence is presented that this value corresponds to a link in the respiratory chain other than that of succino-dehydrogenase or cytochrome c-cytochrome oxidase.

4. Addition of a suitable amount of cresyl blue to a beef heart extract reaction mixture, completely inhibited by cyanide, restores the oxidation of succinate to normal in the presence of pure oxygen. In this system, in which the dye is substituted for the oxidase, when the enzyme extract (dehydrogenase) is made the limiting factor, a µ of 18,500 calories is obtained; when cresyl blue is made the limiting factor, the µ value is 22,000 calories.

5. Results of these experiments indicate that energies of activation are associated not with the enzyme as such, but with the particular reaction steps involving them as catalysts.
PERMEABILITY OF ERYTHROCYTES TO RADIOACTIVE POTASSIUM
Authors: Dean R. B. , Noonan T. R. , Haege L. , Fenn W. O.
Published: May 2004

The diffusion coefficients for the exchange of potassium across the membrane of erythrocytes of humans, rats, and rabbits have been determined by the use of artificially radioactive potassium, both into and out of the erythrocytes both in vitro and in vivo.

The diffusion coefficients found in minutes–1 were 0.2 to 0.25 x 10–3 for human, 0.32 to 0.665 x 10–3 for rabbits, and 1.0 x 10–3 for rat erythrocytes. Rabbit erythrocytes appear to be more permeable in vivo.

Reasons are advanced to explain the failure of earlier workers to demonstrate appreciable exchange of potassium in erythrocytes.
STUDIES ON THE LACTASE OF ESCHERICHIA COLI
Authors: Knopfmacher H. P. , Salle A. J.
Published: May 2004

A "lactase solution" was prepared from Escherichia coli. The mechanism of its action has been studied and changes in the rate of hydrolysis under various conditions investigated.

The hydrolysis of lactose by the enzyme approximates the course of reaction of the integrated Michaelis-Menten equation. One molecule of enzyme combines with one molecule of substrate.

E. coli lactase is readily inactivated at pH 5.0, and its optimal activity at 36°C. is reached between pH 7.0 and pH 7.5.

The optimal temperature for its action was found to be 46°C. when determinations were carried out after an incubation period of 30 minutes.

Its inactivation by heat follows the course of a first order reaction, and the critical thermal increment between the temperatures of 45°C. and 53°C. was calculated to be 56,400 calories per mol.

The enzyme is activated by potassium cyanide, sodium sulfide, and cysteine, and irreversibly inactivated by mercuric chloride, silver nitrate, and iodine.

After inactivation with copper sulfate partial reactivation is possible, while the slight inhibition brought about by hydrogen peroxide is completely reversible.

The possible structure of the active groups of E. coli lactase as compared with other enzymes has been discussed.
THE RATE OF BACTERIOPHAGE INACTIVATION BY FILTRATES OF ESCHERICHIA COLI CULTURES
Authors: Ellis Emory L. , Spizizen John
Published: May 2004

1. The rate of inactivation of an anti-coli phage by filtrates of cultures of the homologous bacteria has been studied.

2. The inactivation rate at 37°C. is proportional to phage concentration and filtrate concentration.

3. At 0°C. the rate of phage inactivation becomes proportional to the square root of the filtrate concentration.

4. A reaction scheme to account for these observations is suggested and discussed.

5. This coli-phage is also inactivated by relatively large concentrations of soluble starch, inulin, gum arabic, and acetylated gum arabic.

6. The inactivation is markedly influenced by salt concentration, being rapid at moderate salt concentrations and slow at high or extremely low salt concentrations.

7. The inactivated phage cannot be regenerated by high salt concentrations, or by soaps.
THE CHLOROPHYLL-PROTEIN COMPOUND OF THE GREEN LEAF
Authors: Smith Emil L.
Published: May 2004

1. Aqueous extracts of spinach and Aspidistra leaves yield highly opalescent preparations which are not in true solution. Such extracts differ markedly from colloidal chlorophyll in their spectrum and fluorescence. The differences between the green leaf pigment and chlorophyll in organic solvents are shown to be due to combination of chlorophyll with protein in the leaf.

2. The effect of some agents on extracts of the chlorophyll-protein compound has been investigated. Both strong acid and alkali modify the absorption spectrum, acid converting the compound to the phaeophytin derivative and alkali saponifying the esterified groups of chlorophyll. Even weakly acid solutions (pH 4.5) denature the protein. Heating denatures the protein and modifies the absorption spectrum and fluorescence as earlier described for the intact leaf. The protein is denatured by drying. Low concentrations of alcohol or acetone precipitate and denature the protein; higher concentrations cause dissociation liberating the pigments.

3. Detergents such as digitonin, bile salts, and sodium desoxycholate clarify the leaf extracts but denature the protein changing the spectrum and other properties.

4. Inhibiting agents of photosynthesis are without effect on the absorption spectrum of the chlorophyll-protein compound.

5. The red absorption band of chlorophyll possesses the same extinction value in organic solvents such as ether or petroleum ether, and in aqueous leaf extracts clarified by digitonin although the band positions are different. Using previously determined values of the extinction coefficients of purified chlorophylls a and b, the chlorophyll content of the leaf extracts may be estimated spectrophotometrically.

6. It was found that the average chlorophyll content of the purified chloroplasts was 7.86 per cent. The protein content was 46.5 per cent yielding an average value of 16.1 parts per 100 parts of protein. This corresponds to a chlorophyll content of three molecules of chlorophyll a and one of chlorophyll bfor the Svedberg unit of 17,500. It is suggested that this may represent a definite combining ratio of a and b in the protein molecule.
SOME EFFECTS OF IODINE AND OTHER REAGENTS ON THE STRUCTURE AND ACTIVITY OF TOBACCO MOSAIC VIRUS
Authors: Anson M. L. , Stanley W. M.
Published: May 2004

1. Denatured tobacco mosaic virus has a number of SH groups corresponding to its total sulfur content of 0.2 per cent. The SH groups were estimated by titration with ferricyanide, tetrathionate, and p-chloromercuribenzoate in guanidine hydrochloride solution and by reduction of the uric acid reagent in urea solution.

2. The SH groups of tobacco mosaic virus or their precursors can be abolished by reaction of the native form of the virus with iodine.

3. Tobacco mosaic virus whose SH groups have been oxidized beyond the S-S stage by iodine but whose tyrosine groups have not been converted into di-iodotyrosine groups still retains its normal biological activity as shown by the number of lesions it causes on Nicotiana glutinosa plants and by the characteristic disease produced in Turkish tobacco plants.

4. The inoculation of Turkish tobacco plants with active virus whose SH groups have been abolished by iodine results in the production of virus with the normal number of SH groups.

5. If enough iodine is added to tobacco mosaic virus or if the iodine reaction is carried out at a sufficiently high temperature, then the tyrosine groups are converted into di-iodotyrosine groups and the virus is inactivated.

6. Tobacco mosaic virus can be almost completely inactivated by iodoacetamide under conditions under which iodoacetamide reacts with few if any of the protein's SH groups.

7. Tobacco mosaic virus is not inactivated by dilute p-chloromercuribenzoate.
THE COURSE OF ROD DARK ADAPTATION AS INFLUENCED BY THE INTENSITY AND DURATION OF PRE-ADAPTATION TO LIGHT
Authors: Haig Charles
Published: May 2004

An increase in the degree of light adaptation causes a decrease in the slope of the subsequent rod dark adaptation function and a displacement of the function to the right on the time axis.

Over a wide range, these changes occur to the same extent whether the increase in the degree of light adaptation is produced by raising the intensity or by prolonging the exposure. Within these limits, the Bunsen-Roscoe reciprocity law applies to the intensity and duration of pre-exposure.

Over a still wider range, dark adaptation has the same course following brief exposure to a bright light as it has following prolonged exposure to a dim light, provided the degree of light adaptation is the same in both instances (as indicated by identical initial dark adaptation thresholds).
LONGITUDINAL IMPEDANCE OF THE SQUID GIANT AXON
Authors: Cole Kenneth S. , Baker Richard F.
Published: May 2004

Longitudinal alternating current impedance measurements have been made on the squid giant axon over the frequency range from 30 cycles per second to 200 kc. per second. Large sea water electrodes were used and the inter-electrode length was immersed in oil. The impedance at high frequency was approximately as predicted theoretically on the basis of the poorly conducting dielectric characteristics of the membrane previously determined. For the large majority of the axons, the impedance reached a maximum at a low frequency and the reactance then vanished at a frequency between 150 and 300 cycles per second. Below this frequency, the reactance was inductive, reaching a maximum and then approaching zero as the frequency was decreased.

The inductive reactance is a property of the axon and requires that it contain an inductive structure. The variation of the impedance with interpolar distance indicates that the inductance is in the membrane. The impedance characteristics of the membrane as calculated from the measured longitudinal impedance of the axon may be expressed by an equivalent membrane circuit containing inductance, capacity, and resistance. For a square centimeter of membrane the capacity of 1 µf with dielectric loss is shunted by the series combination of a resistance of 400 ohms and an inductance of one-fifth henry.
THEORY AND MEASUREMENT OF VISUAL MECHANISMS
Authors: Crozier W. J. , Wolf Ernst
Published: May 2004

For spectral regions associated with violet, blue, green, and red the relation between mean critical flash intensity Im for visual flicker and the flash frequency F is modified as already found with white light when the light time fraction tL in the flash cycle is changed. For a square image 6.13° on a side, foveally fixated, the "rod" and "cone" contributions to the duplex contour are analyzed in the way already used for white. It is pointed out that several customary qualitative criteria for cone functioning do not necessarily give concordant results. The analysis shows that the three parameters of the probability summations giving the "rod" and "cone" curves are changed independently as a function of wave-length composition of the light, and of the light time fraction.

The correlation of these changes, and of those found in the associated variability functions, can be understood in terms of differences in (1) the numbers of neural units potentially excitable and (2) in the numbers of elements of neural effect obtained from them. In a multivariate situation of this kind it is necessary to compare intensities of luminous flux required to activate half the total population of potentially available elements when this total size is held constant for the different conditions. The results of this comparison, for the filtered lights used, are discussed in relation to certain aspects of excitation vs. wave-length. The problem is a general one, arising where the effects produced as a function of a particular variable are concerned. In the distinction between (1) units excited and (2) the actions they produce may be found the clue for the curious fact that with certain wave-lengths the critical intensities are lower than for white. The extension of the observations to other parts of the retina may be expected to further this analysis.
THE ACTIVITY OF PERIPHERALLY STORED NEUROHUMORS IN CATFISHES
Authors: Parker G. H.
Published: May 2004

1. Adrenalin when mixed with olive oil 1:100 and injected subcutaneously into a catfish will produce a marked pale spot and a general blanching of the whole fish. The general blanching will disappear in about a day. The pale spot may last 3 to 4 weeks.

2. Injections of adrenalin in oil 1:1000 to 1:10,000,000 cause the formation of only pale spots in catfishes. Adrenalin in oil 1:100,000,000 has no effect on the fish's color.

3. Acetylcholine, though ordinarily more powerful than adrenalin, when mixed with oil is effective only in high concentrations 1:20 to 1:100. It then produces clusters of moderately dark spots.

4. The pale spot on a catfish due to adrenalin in oil may be temporarily obliterated by intermedin. It will return of itself, and this process may be repeated a number of times. The same is true of the dark spots produced by acetylcholine in oil when subjected to adrenalin. These observations indicate the subcutaneous storage of both adrenalin and acetylcholine in oil.

5. In the natural color changes in catfishes the nervous neurohumors, probably also adrenalin and acetylcholine, appear both to be stored in the fish's lipoids and to serve thus as a means of lenghthening the times of initial color responses till these stores of neurohumors are exhausted.
THE INFLUENCE OF PROTEINS ON THE REACTIVATION OF YEAST INVERTASE
Authors: Wagreich Harry , Schwartz Lawrence I. , Kamin Henry
Published: May 2004

1. Acid-inactivated yeast invertase could not be regenerated in the presence of the proteolytic enzymes trypsin, pepsin, and chymotrypsin.

2. Certain foreign proteins of non-enzymatic nature partially inhibited the reactivation of acid-inactivated invertase.

3. Certain proteins as gelatin, lacto-globulin, and carbohydrate-free horse crystalbumin did not prevent the reactivation of invertase at all.

4. Highly purified reactivated invertase was shown to exhibit an effect typical of original native invertase; that is, acceleration of its activity in presence of foreign protein at pH 3.0.

5. Native invertase was not digested by trypsin and chymotrypsin.

6. The addition of trypsin and chymotrypsin to reactivating invertase did not affect the invertase which had already reverted to the active form, but prevented further reactivation of inactive invertase.
THE VISUAL SYSTEMS OF EURYHALINE FISHES
Authors: Wald George
Published: May 2004

1. The retinas of all marine fishes so far examined except the Labridae, and of all terrestrial vertebrates contain the rhodopsin system alone; those of fresh water fishes the porphyropsin system alone. In the present paper the visual systems of a number of euryhaline fishes are examined—fishes capable of existence in a wide range of salinities, though usually restricted in spawning either to the sea (catadromous) or to fresh water (anadromous).

2. The retinas of the anadromous salmonids (brook trout, rainbow trout, and chinook salmon) contain mixtures of the rhodopsin and porphyropsin systems, predominantly the latter. The retinas of the catadromous eel and the killifish also contain mixtures of both systems, but in reverse proportions. The retinas of the anadromous white perch and alewife contain the porphyropsin system alone.

3. There is therefore an extensive parallelism between the salinity relations of these animals and the composition of their visual systems. All of them possess predominantly or exclusively the visual system commonly associated with the environment in which the fish spawns.

4. These patterns are fixed genetically, and are to a first approximation independent of the history of the individual. They may represent transitional stages in the evolutionary migration of fishes to and from the sea. The presence of both types of visual system in the retinas of some euryhaline fishes incidentally satisfies one formal requirement of two-component color vision.
THE VISUAL SYSTEM AND VITAMINS A OF THE SEA LAMPREY
Authors: Wald George
Published: May 2004

The porphyropsin-vitamin A2 cycle has been found heretofore only in the retinas of bony fishes capable of existence in fresh water. Cyclostomes, due to their primitive and isolated phylogenetic position, might be expected to possess the rhodopsin-vitamin A1 cycle common to marine elasmobranchs, almost all marine teleosts, and all terrestrial vertebrates so far examined. Yet the anadromous sea lamprey, Petromyzon marinus, possesses primarily the porphyropsin system, like an anadromous teleost. This observation greatly extends the phylogenetic association of vitamin A2 with the capacity for freshwater existence.

Compared with freshwater and anadromous teleosts, the lamprey retina contains the porphyropsin system in extremely low concentration.

The remaining eye tissues, like the retina, contain both vitamins A1 and A2, the latter greatly predominant. The livers of larval and adult lampreys, however, appear to contain vitamin A1 alone. This situation also is not without teleost precedent, since the carp and certain anadromous salmonids display similar reversals of vitamin A pattern in the liver and eye tissues.
COUNTERACTING THE RETARDING AND INHIBITORY EFFECTS OF STRONG ULTRAVIOLET ON FUCUS EGGS BY WHITE LIGHT
Authors: Whitaker D. M.
Published: May 2004

1. Strong dosages (20,000–50,000 ergs per mm.2) of ultraviolet light, predominantly of the wave-length 2537 Å, greatly retard and inhibit the development of rhizoids in Fucus eggs irradiated at about 8 hours after fertilization.

2. If white light shines on the eggs after the irradiation by ultraviolet is terminated, the white light causes a considerable degree of recovery from the retarding and inhibiting effects.

3. If strong white light shines on the eggs during the ultraviolet irradiation, its effect is even more marked in protecting the cells from the damaging effects of the ultraviolet.
THE ROLE OF CARBONIC ANHYDRASE IN CERTAIN IONIC EXCHANGES INVOLVING THE ERYTHROCYTE
Authors: Jacobs M. H. , Stewart Dorothy R.
Published: May 2004

1. The acceleration by bicarbonates of the swelling and hemolysis of erythrocytes in solutions of ammonium salts, first reported by Ørskov, is strikingly dependent upon carbonic anhydrase, being almost abolished by inhibitors of this enzyme such as KCN and sulfanilamide, and under suitable conditions being enhanced by its addition to the external solution. This behavior gives support to the theory of "catalyzed diffusion" as an explanation of the Ørskov effect.

2. The inhibitory effects of both sulfanilamide and KCN seem to be capable of complete reversal on washing the erythrocytes in isotonic salt solutions. The full effect of KCN appears almost instantly; that of sulfanilamide requires a period measured in seconds, or possibly even in minutes, to reach its maximum, the delay presumably being due to the slower penetration of the erythrocyte by this substance. Under favorable conditions the effect of concentrations of sulfanilamide of a few hundredths of a milligram per cent can be demonstrated. No similar effects have been obtained with sulfapyridine.

3. Bicarbonates also have a "catalytic" effect on the response of the internal pH of erythrocytes to changes in that of their surroundings. The resulting volume changes of the cell, which otherwise frequently require many minutes for their completion, may take place within a few seconds in the presence of low concentrations of bicarbonates. At a given pH value the effect of the latter substances is chiefly on the rate of the change and only to a minor extent on its magnitude. It may be further accelerated under appropriate conditions by the addition to the cell suspension of carbonic anhydrase, and can be almost abolished by KCN and by sulfanilamide.

4. Volume changes of erythrocytes associated with exchanges of Cl' for SO4'' ions are greatly accelerated by low concentrations of bicarbonates, this effect being likewise dependent upon carbonic anhydrase. There is some evidence that in this case the exchange takes place, at least in part, in two steps: Cl' for HCO3' and HCO3' for SO4''.
THE PHOTOSYNTHETIC EFFICIENCY OF PHYCOCYANIN IN CHROOCOCCUS, AND THE PROBLEM OF CAROTENOID PARTICIPATION IN PHOTOSYNTHESIS
Authors: Emerson Robert , Lewis Charlton M.
Published: May 2004

The absorption spectra of the principal pigment components extracted from Chroococcus cells have been measured, and their sum compared with the absorption of a suspension of living cells. The agreement was sufficiently close so that it was concluded the absorption spectra of the extracted and separated pigment components could be used to obtain estimates of the relative absorption of the various components in the living cells.

The quantum yield of Chroococcus photosynthesis was measured at a succession of wave lengths throughout the visible spectrum, and the dependence of yield on wave length was compared with the proportions of light absorbed by the pigment components. This comparison showed beyond reasonable doubt that the light absorbed by phycocyanin is utilized in photosynthesis with an efficiency approximately equal to that of the light absorbed by chlorophyll. The light absorbed by the carotenoid pigments of Chroococcus seems for the most part to be unavailable for photosynthesis. The results leave open the possibility that light absorbed by the carotenoids is active in photosynthesis, but with an efficiency considerably lower than that of chlorophyll and phycocyanin. It is also possible that the light absorbed by one or a few of the several carotenoid components is utilized with a high efficiency, while the light absorbed by most of the components is lost for photosynthesis.
PURIFICATION OF THROMBIN
Authors: Milstone H.
Published: May 2004

1. Under certain conditions crude prothrombin changes to thrombin without the addition of extraneous activators and in the absence of ionic calcium.

2. Thrombin is soluble in 0.45 saturated ammonium sulfate, whereas crude prothrombin is not.

3. Partially purified thrombin is comparatively stable in concentrated ammonium sulfate solutions at pH 5.2.

4. A method based on the above facts yields a thrombin preparation the specific activity of which is 100 to 175 times the potential specific activity of whole plasma.
THE INFLUENCE OF DETERGENTS ON SOME PHYSIOLOGICAL PHENOMENA, ESPECIALLY ON THE PROPERTIES OF THE STELLATE CELLS OF THE FROG LIVER
Authors: Höber Rudulf , Höber Josephine
Published: May 2004

1. After a consideration of the physicochemical properties of detergents, it was deemed worth while to study some of their physiological effects. As nonpolar-polar electrolytes, the detergents are surface-active and as such cytolytics; but probably due to their dispersing and wetting properties, they are cytolytic in a fashion different from that of other cytolytics. The detergents tested were alkyl sulfonates, alkyl sulfosuccinates, and bile salts.

2. The cytolytic power has been tested in two ways, (1) with red cells by following the escape of hemoglobin, (2) with muscles by measuring the development of an injury potential. In both series of experiments the threshold concentrations of action have been determined. The effect on the potentials has proved to be, in general, reversible.

3. The hemolytic and the myolytic power run fairly parallel to the surface activity.

4. Dehydrocholate has been found to be lacking in nonpolar-polar properties.

5. The stellate cells (Kupffer cells) of the Ringer-perfused frog liver are unable to take up colloidal dyestuffs (trypan blue and soluble blue R), except after addition of a small amount of serum to the perfusing Ringer solution. Only under the latter conditions, the uptake of dye is increased by adding a detergent. This seems to be due to the combined action of the proteins and the detergents.

6. The effect of relatively high concentrations of detergent is disintegration of the stellate cells; viz., cytolysis. There are reasons to assume that small concentrations, which produce a threshold increase of the dyestuff uptake, raise the functional activity.
STUDIES ON CELL METABOLISM AND CELL DIVISION
Authors: Krahl M. E. , Jandorf Bernhard J. , Clowes G. H. A.
Published: May 2004

1. Methods suitable for the determination of diphosphothiamine (cocarboxylase) in eggs of Arbacia punctulata have been developed. Quantitative extraction of the cocarboxylase was effected by combining the use of thiamine hydrochloride in the extraction fluid with critical adjustment of the pH of extraction to pH 6.3–6.7.

2. The unfertilized eggs were found to contain the equivalent of 2 to 3 micrograms of natural yeast cocarboxylase per gm. of wet eggs; the cocarboxylase content of the 30 minute and 10 hour fertilized eggs was somewhat less (Table III).

3. In preliminary experiments, Arbacia egg cytolysates were found to cause pyruvic acid to disappear. The rate of such disappearance was apparently greater under aerobic than under anaerobic conditions; it was also greater for cytolysates from fertilized eggs than for cytolysates from unfertilized eggs (Table IV).
STUDIES ON CELL METABOLISM AND CELL DIVISION
Authors: Jandorf Bernhard J. , Krahl M. E.
Published: May 2004

1. The diphosphopyridine nucleotide content of Arbacia eggs has been measured manometrically and found to be approximately 250–500 micrograms per gm. wet weight of eggs, the value varying with individual egg samples and with the state of development of the eggs. Of the total diphosphopyridine nucleotide present, approximately 25–40 per cent is in an alkali-stable, presumably the dihydro, form.

2. Tests for triosephosphate and glutamic acid dehydrogenases carried out on Arbacia egg cytolysates were negative.
THE CHLOROPHYLL-PROTEIN COMPLEX
Authors: Fishman Myer , Moyer Laurence S.
Published: May 2004

1. Reported effects of different conditions on the stability of the purified chlorophyll-protein complex have been confirmed.

2. The electrophoretic behavior of the chlorophyll-protein complex prepared from two unrelated species of plants (Aspidistra elatior and Phaseolus vulgaris) has been investigated and shown to be dissimilar. In M/50 acetate buffer at 25°C, the isoelectric point of the complex from Phaseolus is at pH 4.70, whereas that from Aspidistra is at pH 3.9 (extrapolated). These values fall within the usual range of protein isoelectric points.

3. Treatment with weak acids causes an irreversible denaturation of the protein complex from both species, with a resultant shift in the mobility-pH curves to more basic values.

4. Differences in electrophoretic behavior between the chlorophyll-protein complex and the cytoplasmic proteins of Phaseolus have been demonstrated. The isoelectric point of the latter is at pH 4.22.
HYDROSTATIC PRESSURE AND TEMPERATURE IN RELATION TO STIMULATION AND CYCLOSIS IN NITELLA FLEXILIS
Authors: Harvey E. Newton
Published: May 2004

Nitella flexilis cells are not stimulated to "shock stoppage" of cyclosis by suddenly evacuating the air over the water or on sudden readmission of air, or on suddenly striking a piston in the water-filled chamber in which they are kept with a ball whose energy is 7.6 joules, provided the Nitella cell is not moved by currents against the side of the chamber.

Sudden increases in hydrostatic pressure from zero to 1000 lbs. or 0 to 5000 lbs. per square inch or 5000 to 9000 lbs. per square inch usually do not stimulate to "shock stoppage" of cyclosis, but some cells are stimulated. Sudden decreases of pressure are more likely to stimulate, again with variation depending on the cell.

In the absence of stimulation, the cyclosis velocity at 23°C. slows as the pressure is increased in steps of 1000 lbs. per square inch. In some cells a regular slowing is observed, in others there is little slowing until 4000 to 6000 lbs. per square inch, when a rapid slowing appears, with only 50 per cent to 30 per cent of the original velocity at 9000 lbs. per square inch. The cyclosis does not completely stop at 10000 lbs. per square inch. The pressure effect is reversible unless the cells have been kept too long at the high pressure.

At low temperatures (10°C.) and at temperatures near and above (32°–38°C.) the optimum temperature for maximum cyclosis (35–36°C.) pressures of 3000 to 6000 lbs. per square inch cause only further slowing of cyclosis, with no reversal of the temperature effect, such as has been observed in pressure-temperature studies on the luminescence of luminous bacteria.

Sudden increase in temperature may cause shock stoppage of cyclosis as well as sudden decrease in temperature.
THE RELATIONS OF TEMPERATURE TO THE POTASSIUM EFFECT AND THE BIOELECTRIC POTENTIAL OF VALONIA
Authors: Blinks L. R.
Published: May 2004

The effect of temperature upon the bioelectric potential across the protoplasm of impaled Valonia cells is described. Over the ordinary tolerated range, the P.D. is lowest around 25°C., rising both toward 15° and 35°. The time curves are characteristic also. The magnitude of the temperature effect can be controlled by changing the KCl content of the sea water (normally 0.012 M): the magnitude is greatly reduced at 0.006 M KCl, enhanced at 0.024 M, and greatly exaggerated at 0.1 M KCl.

Conversely, temperature controls the magnitude of the potassium effect, which is smallest at 25°, with a cusped time course. It is increased, with a smoothly rising course, at 15°, and considerably enhanced, with only a small cusp, at 35°. A temporary "alteration" of the protoplasmic surface by the potassium is suggested to account for the time courses. This alteration does not occur at 15°; the protoplasm recovers only slowly and incompletely at 25°, but rapidly at 35°, in such fashion as to make the P.D. more negative than at 15°. This would account for the temperature effects observed in ordinary sea water.