bluuebunny/crossref_metadata_2025 huggingface dataset:
THE DEATH WAVE IN NITELLA
Authors: Osterhout W. J. V. , Harris E. S.
Published: May 2004

The hypothesis of protoplasmic layers enables us to predict the bioelectrical behavior of the cell under a great variety of conditions. It is shown in the present paper that this is clearly the case when a death wave passes through different points in contact with unlike solutions.
FRACTIONATION OF GELATIN
Authors: Kunitz M. , Northrop John H.
Published: May 2004

1. It is possible to fractionate gelatin by means of reprecipitation at 23°C. of a salt-free solution of pH 4.7 into two fractions, one of which is soluble in water at any temperature, and a second one which does not dissolve in water even when heated to 80°C.

2. The proportion of the soluble fraction in gelatin is much greater than of the insoluble one.

3. The insoluble fraction of gelatin does not swell when mixed with water, but it does swell in the presence of acid and alkali which finally dissolve it.

4. Blocks of concentrated gel made by dissolving various mixtures of the soluble and insoluble fractions of gelatin in dilute NaOH swell differently when placed in large volumes of dilute buffer solution pH 4.7 at 5°C. The gel consisting of the insoluble material shows only a trace of swelling, while those containing a mixture of soluble and insoluble swell considerably. The swelling increases rapidly as the proportion of the soluble fraction increases.

5. A 5 per cent gel made up by dissolving the insoluble fraction of gelatin in dilute NaOH loses about 70 per cent of its weight when placed in dilute buffer pH 4.7 at 5°C. A similar gel made up of ordinary gelatin loses only about 20 per cent of its weight under the same conditions.

6. It was not found possible to resynthesize isoelectric gelatin from its components.

7. An insoluble substance similar in many respects to the one obtained by reprecipitation of gelatin is produce on partial hydrolysis of gelatin in dilute hydrochloric acid at 90°C.
THE SWELLING OF GELATIN AND THE VOLUME OF SURROUNDING SOLUTION
Authors: Northrop John H. , Kunitz M.
Published: May 2004

The swelling of isoelectric gelatin added to various volumes of acid of different concentration at 5°C. has been determined. The swelling is determined only by the concentration of the supernatant solution at equilibrium and is independent of the volume of acid.

Similar experiments with unpurified gelatin show that in this case, owing to the presence of neutral salts the swelling is a function of the volume as well as the concentration of acid.

Both results are predicted by the Procter-Wilson-Loeb theory of the swelling of gelatin.
A METHOD FOR THE DETERMINATION OF DIFFUSION CONSTANTS AND THE CALCULATION OF THE RADIUS AND WEIGHT OF THE HEMOGLOBIN MOLECULE
Authors: Northrop John H. , Anson M. L.
Published: May 2004

A method is described for determining the diffusion coefficient of solutes by determining the rate of passage of the solute through a thin porous membrane between two solutions of different concentration.

The method has been used to determine the diffusion coefficient of carbon monoxide hemoglobin. This was found to be 0.0420 ± 0.0005 cm.2 per day at 5°C.

The molecular weight of carbon monoxide hemoglobin calculated by means of Einstein's equation from this quantity is 68,600 ± 1,000.
THE RELATION BETWEEN TEMPERATURE AND THE PEDAL RHYTHM OF BALANUS
Authors: Cole William H.
Published: May 2004

1. The relation of temperature to the pedal rhythm of Balanus balanoides L. has been studied under otherwise constant conditions.

2. The frequency of movement increases with temperature, showing three groups of thermal increments and three critical temperatures. Five animals yielded µ = 5,700 above 14.5° C. and 12,100 below; 3 gave µ = 7,800 above 9.3° and 22,500 below; while 9 showed µ = 9,500 above 8.1° and 22,100 below.

3. The upper critical temperatures, above which different effects appeared in different animals were 23.4°, 26.0°, and 27.0°. Above 27.0° none of the valves remained open.

4. Excepting the values 5,700 and 9,500, the increments are similar to those previously found to be associated with respiratory and with neuromuscular activities.

5. Dilution of the sea water with from 3 to 4 per cent fresh water decreases the rate without altering the increments. More than 4 per cent dilution causes irregularity.
THE RELATION BETWEEN MAXIMUM RATE OF PHOTOSYNTHESIS AND CONCENTRATION OF CHLOROPHYLL
Authors: Emerson Robert
Published: May 2004

Willstätter and Stoll have studied the rate of photosynthesis as a function of chlorophyll content. However, their experiments fail to reveal any regular relationship between these two quantities, probably because, in order to obtain material differing widely in chlorophyll content, they were obliged to use leaves which were not comparable in other respects. The writer describes a method for varying the chlorophyll content per unit volume of cells of Chlorella vulgaris, maintaining other factors constant.

Experiments are described which show that the maximum rate of photosynthesis is a smooth function of the chlorophyll content.
RESPIRATION AND GEOTROPISM IN VICIA FABA. I
Authors: Navez A. E.
Published: May 2004

In this paper there are given the results of a study of the relation of respiration to temperature, in seedlings of Vicia faba, and of the onset of geotropic response. It is shown that with due care and very accurate control of temperature constancy, one can get constant excretion of CO2 even over fairly long periods. The treatment of the experimental data shows that the Q10 ratio is of course a valueless "constant," as it is variable; but that the figure obtained for µ, the temperature characteristic (critical thermal increment), 16,250, is perfectly consistent with the values previously obtained for µ in respiratory oxidative processes in similar material. New data on the reaction time for the root of Vicia faba seedlings excited geotropically are given also. The study of the dependence of this time relation on temperature shows µ = 16,110, agreeing quantitatively with the value deduced previously from the relevant data of earlier investigators (Crozier, 1924). This points to the importance of some respiratory oxidative process as the agency controlling the onset of geotropic curvature.
GEOTROPIC ORIENTATION IN ARTHROPODS
Authors: Crozier W. J. , Stier T. J. B.
Published: May 2004

The creeping of the beetle Tetraopes tetraopthalmus during negatively geotropic orientation shows the angles of orientation (θ) on a surface inclined at α° to the horizontal to be proportional to sin α. The direction of orientation easily suffers temporary reversal to positive as result of handling. Mechanical stability during upward progression should be just possible when K1 cot α = K2 sin θ + K3 cos θ, the weight of the body being supported on the tripod formed by the legs on either side and by the posterior tip of the abdomen. Lack of this stability produces tensions on the legs through (1) the bilaterally distributed pull of the body mass on the legs, and (2) the torque on the legs due to the weight of the abdomen. The downward gravitational displacement of the tip of the abdomen causes K2 and K3 in the preceding formula to be functions of α.

These relations have been tested in detail by shifting the location of the center of gravity, by attaching additional masses anteriorly and posteriorly, and by decreasing the total load through amputation of the abdomen; the latter operation changes the conditions for stability.

Different formulæ are thus obtained (cf. earlier papers) for the orientation of animals in which the mechanics of progression and the method of support of the body weight on an inclined surface are not the same. This demonstrates in a direct way that the respective empirical equations cannot be regarded as accidents. The results are in essence the same as that already obtained with young mammals. The diversity of equations required for the physically unlike cases merely strengthens the conception of geotropic orientation as limited by the tensions applied to the musculature of the body (caterpillars, slugs) or of appendages (beetles, and certain other forms) when the body is supported upon an inclined surface, since equations respectively pertaining to the several instances, and satisfactorily describing the observations, are deduced on this basis.
CHEMICAL ANTAGONISM OF IONS
Authors: Simms Henry S.
Published: May 2004

The pH of a 0.01 molar solution of glycine, half neutralized with NaOH, is 9.685. Addition of only one of the salts NaCl, KCl, MgCl2, or CaCl2 will lower the pH of the solution (at least up to 1 µ).

If a given amount of KCl is added to a glycine solution, the subsequent addition of increasing amounts of NaCl will first raise the pH (up to 0.007 M NaCl). Further addition of NaCl (up to 0.035 M NaCl) will lower the pH, and further additions slightly raise the pH.

The same type of curve is obtained by adding NaCl to glycine solution containing MgCl2 or CaCl2 except that the first and second breaks occur at 0.015 M and 0.085 M NaCl, respectively.

Addition of CaCl2 to a glycine solution containing MgCl2 gives the same phenomena with breaks at 0.005 M and 0.025 M CaCl; or at ionic strengths of 0.015 µCaCl2 and 0.075 µCaCl2. This indicates that the effect is a function of the ionic strength of the added salt.

These effects are sharp and unmistakable. They are almost identical with the effects produced by the same salt mixtures on the pH of gelatin solutions. They are very suggestive of physiological antagonisms, and at the same time cannot be attributed to colloidal phenomena.
NOTE ON THE NATURE OF THE CURRENT OF INJURY IN TISSUES
Authors: Osterhout W. J. V. , Harris E. S.
Published: May 2004

Leading off from two places on the same cell (of Nitella) with 0.001 M KCl we observe that a cut produces only a temporary negative current of injury.

If we lead off with 0.001 M KCl from any cell to a neighboring cell we find that when sap comes out from the cut cell and reaches the neighboring intact cell a lasting negative "current of injury" is produced. This depends on the fact that the intact cell is in contact with sap at one point and with 0.001 M KCl at the other (this applies also to tissues composed of small cells).

If we employ 0.1 M KCl in place of 0.001 M the current of injury with a single cell is positive (and is more lasting when a neighboring cell is present).

Divergent results obtained with tissues and single cells may be due in part to these factors.
THE PREPARATION OF RELATIVELY PURE BACTERIOPHAGE
Authors: Krueger A. P. , Tamada H. T.
Published: May 2004

The method described above, based on the electrophoretic migration of bacteriophage particles into an agar gel and their subsequent re-suspension in a suitable medium, has the following advantages:

It is simple and can be readily carried out on a comparatively large scale by merely inserting additional units between the same electrode cups. It requires but one extraction and the resulting phage suspension is strongly lytic, an average sample being capable of completely lysing susceptible bacteria at a dilution of 10–16. The suspension contains no proteins demonstrable by the biuret, alcohol, xanthoproteic, Millon or Hopkins-Cole reactions and yields but 0.044 mg. N/cc. directly attributable to the phage. Each corpuscle contains no more nitrogen than a single molecule of protein.

In addition the method is applicable to determinations of the electric charge carried by biologically active substances of small dimensions, e.g., phage, toxins, and perhaps some viruses. It offers as well a possible means of purification of these substances.

The purified bacteriophage obtained by such a procedure or similar ones is relatively unstable. Work now in progress indicates that it does not possess nearly the resistance to chemical agents, drying, etc., that non-purified phage displays.

It is suggested that experiments designed to test the therapeutic value of bacteriophage be conducted, when possible, with purified suspensions thereby avoiding any possibility of obscure non-specific reactions due to other constituents of the lysates.
A STUDY OF THE BACTERICIDAL ACTION OF ULTRA VIOLET LIGHT
Authors: Gates Frederick L.
Published: May 2004

In this first paper of a series on the bactericidal action of ultra violet light the methods of isolating and measuring monochromatic radiations, of preparing and exposing the bacteria, and of estimating the effects of exposure, are given in detail.

At all the different wave lengths studied the reactions of S. aureus followed similar curves, but occurred, at each wave length, at a different energy level. The general similarity of these curves to those for monomolecular reactions provokes a discussion of their signifiance, and emphasis is laid upon variations in susceptibility of individual organisms, due especially to age and metabolic activity, so that the typical curve seems to be best interpreted as one of probability.
SPECTROPHOTOMETRIC STUDIES OF PENETRATION OF DYES
Authors: Irwin Marian
Published: May 2004

Spectrophotometric measurements show that the non-medullated nerve of a lobster claw is capable of absorbing methylene blue, azure B, or acid fuchsin dissolved in sea water but this does not necessarily imply that the dyes penetrate into the interior of the nerve.
THE PREPARATION OF A GRADED SERIES OF ULTRAFILTERS AND MEASUREMENT OF THEIR PORE SIZES
Authors: Krueger A. P. , Ritter R. C.
Published: May 2004

A simple procedure for making a series of membranes of graded pore sizes is presented with data for permeability of the membrane series to water and to colloidal sols of known particle sizes. A convenient ultrafiltration apparatus for operation under aseptic conditions is described.
NEGATIVE VARIATIONS IN NITELLA PRODUCED BY CHLOROFORM AND BY POTASSIUM CHLORIDE
Authors: Osterhout W. J. V. , Hill S. E.
Published: May 2004

The results of applying chloroform and KCl to Nitella indicate that a negative variation may be started whenever it is possible to set up along the protoplasm a gradient of potential difference sufficiently steep to produce the necessary outward flow of current. Successive variations may thus be set up.
THE DIRECT CURRENT RESISTANCE OF NITELLA
Authors: Blinks L. R.
Published: May 2004

The electrical resistance of Nitella cells to direct current is determined in a Wheatstone bridge, using a vacuum-tube detector, and string galvanometer. Very small currents are passed through the cells, to avoid stimulation. The galvanometer record shows typical transient effects in the living cells at opening and closing of the circuit, due to the development of back E.M.F.

With 1 cm. contacts of tap water, and 1 cm. between contacts the resistances of living cells are usually between 1,000,000 and 2,000,000 ohms. They go as high as 3,500,000 ohms when the cells are in the best condition. The resistance falls to about 50,000 ohms immediately after killing.

Leakage around the cell is small because the wall is imbibed with tap water. By measuring the resistance of the isolated wall (air-filled), and by varying the areas of contact with intact cells, the effective protoplasmic resistance is calculated. This varies from 100,000 to 700,000 ohms per square centimeter of surface, with a typical value of about 250,000 ohms per square centimeter.

This high resistance represents a low permeability for most ions, since the values are nearly as high with contacts of 0.01 M NaCl, CaCl2, LiCl, NH4Cl, and MgSO4. The resistances are greatly reduced however by solutions of KCl, which is correlated with a high mobility of the K+ ion in the protoplasm.

Electrical stimulation causes a marked reduction of resistance, which may be due to exomosis of KCl.
SALT BRIDGES AND NEGATIVE VARIATIONS
Authors: Osterhout W. J. V. , Hill S. E.
Published: May 2004

A negative variation in Nitella is unable to pass a spot killed by chloroform but can set up a negative variation beyond this spot when a salt bridge is put around it. It can likewise set up a negative variation in a cell of another plant if connected to it by two salt bridges.
FORWARD MOVEMENT OF PARAMECIUM AS A FUNCTION OF THE HYDROGEN ION CONCENTRATION
Authors: Chase Aurin M. , Glaser Otto
Published: May 2004

1. At constant temperatures, and within physiological limits, changes of pH in either direction from the neutral point result in immediate increases in speed of movement of Paramecium.

2. These increases are temporary. In 30 to 45 minutes a minimum of speed is reached. This is followed by a period of recovery lasting about an hour. Finally an equilibrium is found. With inorganic acids (HCl or H2SO4) the final speed after 3 or 4 hours is that characteristic of prolonged exposure to pH 7.0; on the other hand, 3 or 4 hours after the application of either valeric or carbonic acid, speed is proportional to the [H^prime;] of the external and, probably, of the internal medium.

3. These facts become explicable if we assume that the ionization of an ampholyte superficially localized is essential for the execution of the ciliary stroke. Valeric and carbonic acid, in time, demonstrably penetrate the cell. As a working hypothesis we postulate that internal increase of the [H'] accelerates the rate at which this ampholyte is synthetized; but without actually penetrating the cell, hydrogen or hydroxyl ions in the external medium could also increase the degree to which this ampholyte dissociates.

4. Increased ionization of a fixed quantity of ampholyte and an increase in the rate of its production are in these experiments practically indistinguishable. Hence we assume that immediate and temporary increases of speed resulting from any change of pH, as well as final and permanently higher speed levels manifest only after prolonged exposures to organic acids, involve essentially the same mechanism.
HEATING OF SIMPLE SOLUTIONS AND EMULSIONS EXPOSED TO HIGH FREQUENCY HIGH POTENTIAL ELECTROSTATIC FIELDS
Authors: Marshall W. H.
Published: May 2004

1. It is shown that the absorption in liquid dielectrics is a function of potential gradient (field intensity) as well as frequency and that for values of potential gradient above, at least 70 volts per millimeter, the rate of rise of temperature-frequency curve increases rapidly with frequency.

2. The presence of ions in measurable quantity considerably changes the absorption characteristics and apparently causes the values to remain constant, whereas the values for water drop about 40 per cent, during exposure. The absorption also changes rapidly with the concentration of the electrolyte.

3. Very high absorption values are found for an emulsion of cotton-seed oil in 1 per cent sodium oleate. It is shown that the absorption is due to the colloidal structure (with the possibility that the energy is dissipated at the phase boundaries).
ELECTROKINETIC PHENOMENA. II
Authors: Abramson Harold A.
Published: May 2004

Two theories which predict different values for the ratio of VE, the electroendosmotic velocity of a liquid past a surface, to Vp, the electric mobility of a particle of the same surface through the same liquid are discussed. The theory demanding that

See PDF for Equation

was supported by certain data of van der Grinten for a glass surface. Re-calculation of van der Grinten's data reveals that the ratio varies between 2.1 and 2.8. These results are in accord with previous data of Abramson. It is pointed out that glass is unsuitable for the investigation.

The ratio

See PDF for Equation

is here determined for a flat surface and particles when both are covered by the same proteins. Under these conditions

See PDF for Equation

The theory is similarly tested for a round surface using a micro-cataphoresis cell. It is shown that

See PDF for Equation

for a round surface is approximately 1.00. These findings are confirmatory of previous data supporting the view that cataphoretic mobility is independent of the size and shape of the particles when all particles compared have similar surface constitutions.
ON THE MECHANISM OF OPSONIN AND BACTERIOTROPIN ACTION
Authors: McCutcheon Morton , Mudd Stuart , Strumia Max , Lucké Balduin
Published: May 2004

Sensitization with increasing concentrations of homologous immune serum shifts the isoelectric point of the antigens studied progressively to the alkaline side. Antigens maximally sensitized with rabbit sera have shown isoelectric points of pH 5.6 to 5.8. The globulins precipitated or salted out of the same immune sera have been isoelectric at pH 5.1 to 5.2.

The combination of antigen with antibody depends of course upon specific affinities; the surface properties of the sensitized antigen, agglutination and phagocytosis depend primarily upon the properties of the sensitizing serum substances combined with and deposited on the antigen surface.
RESPIRATION OF MAMMALIAN ERYTHROCYTES
Authors: Michaelis L. , Salomon K.
Published: May 2004

Non-nucleated mammalian erythrocytes do not respire even in the presence of sugar, but they do respire after addition of a small amount of methylene blue.

It is shown in this paper that aqueous extracts of various organs, especially liver, act in the same way as methylene blue. The respiration of erythrocytes induced by an organ extract is not altered in the presence of carbon monoxide.

The content of this respiratory supplement in extracts of organs varies according to the organ: liver and kidney show the best effect; muscle, brain, and blood serum the least.

With hemolyzed erythrocytes no respiration can be induced either by methylene blue or by organ extracts.
CRYSTALLINE PEPSIN
Authors: Northrop John H.
Published: May 2004

A method is described for the preparation of a crystalline protein from commercial pepsin preparations which has powerful peptic activity. The composition, optical activity, and proteolytic activity of this protein remain constant through seven successive crystallizations. No evidence for the presence of a mixture or of a solid solution is found in a study of the solubility of the protein in a series of different salt solutions, nor from the diffusion coefficient or from the rate of inactivation. These results indicate that the material is a pure substance or possibly a solid solution of two or more substances having nearly the same solubility in all the various solvents studied. It seems reasonable to conclude from these experiments that the possibility of a mixture must be limited to a mixture of proteins, so that the conclusion seems justified that pepsin itself is a protein.
STUDIES ON PENETRATION OF DYES WITH GLASS ELECTRODE
Authors: Irwin Marian
Published: May 2004

Glass electrode measurements of the pH value of the sap of Nitella show that cresyl blue in form of free base penetrates the vacuoles and raises pH value of the sap to about the same degree as the free base of the dye added to the sap in vitro, while the dye salt dissolved in the sap does not alter its pH value. It is proved conclusively that the increase in the pH value of the sap is due only to the presence of the dye and not to some other alkaline substance.

Spectrophotometric measurements show that the dye which penetrates the vacuole is chiefly cresyl blue.

When the protoplasm is squeezed into the sap, the pH value of the sap is higher than that of the pure sap. Such a mixture behaves very much like the sap in respect to the dye.
THE INTRINSIC RHYTHM OF THE TURTLE'S HEART STUDIED WITH A NEW TYPE OF CHRONOGRAPH, TOGETHER WITH THE EFFECTS OF SOME DRUGS AND HORMONES
Authors: Loomis Alfred L. , Harvey E. Newton , MacRae C.
Published: May 2004

A chronograph is described for recording continuously the rates of many different kinds of rhythmic processes over long time periods. The rate is read directly from the length of a line of ink, drawn by a moving pen.

Rates of beat of excised turtle's hearts in Ringer's solution have been recorded at 25°C. under constant conditions of temperature, pH, and oxygen supply for periods of 36 hours. Regular periodic variations in the fundamental rhythm are figured, as well as rates of extraordinary constancy. The effects of adrenalin, ephedrin, thyroxin, α and ß pituitary hormone insulin, nicotin, and atropin are described in the text.
THE ACCUMULATION OF ELECTROLYTES
Authors: Cooper Wm. C. , Osterhout W. J. V.
Published: May 2004

When 0.005 M NH4Cl is added to sea water containing cells of Valonia macrophysa ammonia soon appears in the sap and may reach a concentration inside over 40 times as great as outside. It appears to enter as undissociated NH3 (or NH4OH) and tends to reach a pseudoequilibrium in which the activity of undissociated NH3 (or NH4OH) is the same inside and outside.

When ammonia first enters, the pH value of the sap rapidly rises but it soon reaches a maximum and subsequently falls off. At the same time there is an increase of halide in the sap which, however, does not run a parallel course to the ammonia accumulation, but it comes to a new equilibrium value and remains constant.

The increase in NH3 in the sap is accompanied by a decrease in the concentration of K.

As NH3 enters the specific gravity of the sap decreases and the cells rise to the surface and continue to grow as floating organisms. The growth of the cells is increased.
THE REACTIONS OF CYANIDE WITH GLOBIN HEMOCHROMOGEN
Authors: Anson M. L. , Mirsky A. E.
Published: May 2004

Cyanide can react with globin hemochromogen in two different ways. In the first reaction cyanide combines with globin hemochromogen without displacing or competing with globin. In the second reaction cyanide displaces globin.
THE ARGININE AND PREARGININE GROUPS IN EDESTIN
Authors: Simms Henry S.
Published: May 2004

The author corroborates the data of Schmidt showing that the dissociation index of the third group of arginine is pK3' = 12.5.

New titration data of edestin have been obtained in very alkaline solutions and show that there is a corresponding group with a titration index of pG' = 12.0, but present in much less quantity than can account for the arginine found on hydrolysis. The data support the theory that the combination of strong base or strong acid with proteins is produced by the formation of salts with the "extra groups" of those trivalent amino acids which can be isolated from the protein, with the exception of arginine. Arginine contributes to the titration curve in much smaller amount than is found on hydrolysis. This deficiency in the arginine group may be accounted for by the basic group in proteins having a titration index of pG' = 3.8 to 4.6 (depending on the protein), which apparently yields arginine on hydrolysis, and may properly be called prearginine.
ELECTROKINETIC PHENOMENA. III
Authors: Abramson Harold A.
Published: May 2004

A survey of the published electrophoretic mobilities of certain mammalian red cells reveals that the isoelectric points accorded to these cells are the result of equilibria incidental to red cell destruction. The electrophoretic mobilities of normal washed sheep and human cells have now been studied in 0.85 per cent NaCl solutions from about pH 3.6 to 7.4. All measurements were made within 2 minutes of the preparation of the suspension of red cells. In no case was reversal of sign of charge observed under these conditions. Reversal of sign of charge occurred only after sufficient time had elapsed to permit sufficient adsorption of the products of red cell destruction. There is little change in mobility as the pH of the medium is decreased. Reversal of sign of charge does occur in the presence of normal and immune (anti-sheep) rabbit sera. The isoelectric point determined under these conditions does not appear to be connected specifically with the immune body but is perhaps associated with phenomena incidental to red cell destruction and the presence of serum. The characteristic lowering of mobility by amboceptor occurs, however, from pH 4.0 to pH 7.4. The curves of mobility plotted against pH for normal and for immune sera support the viewpoint that the identity of the isoelectric points for normal and sensitized sheep cells is not primarily concerned with the immune reaction. It is most unlikely that an "albumin" or a "globulin" surface covers red cells with a complete protein film. Although serum protein reacts with red cells in acid solutions, this is not demonstrable for gelatin. The lowering of mobility usually ascribed to anti-sheep rabbit serum may also occur, but to a lesser degree, in normal rabbit serum. This diminution of mobility is not, in the first place, associated with sensitization to hemolysis induced by complement. This supports the view that only a very small part of the red cell surface need be changed in order to obtain complete hemolysis in the presence of complement.
THE CONDITIONS OF RECOVERY OF TRANSMISSIVITY OF NEWLY REPASSIVATED IRON WIRES IN NITRIC ACID
Authors: Lillie Ralph S.
Published: May 2004

1. Passive steel wires were activated in a bath (Bath A) containing 70 v. per cent HNO3 (in which they undergo prompt repassivation), and immediately transferred to a second bath (Bath B) containing HNO3 of a concentration varying in different experiments. After varying intervals in this bath they were transferred while still passive to a third bath (Bath C) containing strong HNO3 (70 or 100 v. per cent) and there immediately activated.

2. During the immersion in Bath B the wires progressively recover their ability to transmit activation waves in strong HNO3. The measure of this recovery is the distance travelled by the activation waves in Bath C after the varying times of exposure in Bath B. Transmissivity as thus measured is at first incomplete (decremental) and later becomes complete. The minimal exposures in Bath B required to render wires completely transmissive in the strong acid of Bath C were determined for concentrations of HNO3 between 10 and 100 v. per cent. With 100 v. per cent HNO3 in Bath C, these exposures range from 40 minutes or more in 15 v. per cent to 10 minutes in 100 v. per cent HNO3 (temperature 19–20° in all baths).

3. The time required for complete recovery varies inversely with the concentration of the acid in the recovery bath (Bath B), but increases rapidly with the concentration of the acid in the testing bath (Bath C). Hence at a time when a wire has recovered just sufficiently to transmit non-decrementally in a given strong acid (e.g., 70 v. per cent) it still transmits decrementally in a stronger acid. Complete recovery for transmission in 100 v. per cent HNO3 requires about twice as long as for 70 v. per cent HNO3. In HNO3 of 50 v. per cent and less decremental transmission does not occur.

4. The indications are that recovery is an effect of the progressive solvent action of the external acid on the passivating oxide film, which at its first deposition appears to be relatively thick and hence resistant to electrochemical reduction. The final stage of recovery, when electrical sensitivity and speed of transmission are maximal, would on this hypothesis correspond to minimal thickness, possibly monomolecular.

5. The rate of recovery in Bath B is not far from proportional to the concentration of HNO3 in the more dilute solutions, but in the higher, especially the strongly passivating, concentrations (70 to 100 v. per cent) the rate becomes appreciably slower than proportional, apparently because of the intense oxidizing action of these solutions, which reinforces the oxide sheet and retards the thinning process.

6. The bearing of these observations on the problem of the conditions of recovery in irritable living tissues (such as nerve) during the absolute and relative refractory periods is briefly discussed.
THE DEATH WAVE IN NITELLA
Authors: Osterhout W. J. V. , Hill S. E.
Published: May 2004

Cutting a cell of Nitella sets up a series of rapid electrical responses, transmitted at a rate too rapid to be measured by means of our records. These are followed by slower responses whose speed falls off as the distance from the cut increases, as though they were caused by a mechanical disturbance whose intensity falls off as it travels.

The faster responses seem to be due to the motion of sap past protoplasmic surfaces which have suffered little or no alteration (they seem to be similar to the electrical changes following a blow on the end of a soft rubber tube containing Ag-AgCl electrodes). The slower responses appear to be due to alterations in the protoplasm and are usually irreversible.
ON CHROMOSOME BALANCE AS A FACTOR IN DURATION OF LIFE
Authors: Gowen John W.
Published: May 2004

This paper presents a study of the influence of chromosome balance on duration of life in Drosophila. The balanced type of cells are shown to favor a longer life than are the unbalanced type.

Under the identical conditions of the experiment, the type females live an average of 33.1±.6 days; the type males 28.9±.8 days; the triploid females 33.1±.8 days and the sex-intergrade females 15.0±.3 days. The unbalance of the chromosomes and therefore of the genes contained within them is evidently a fundamental factor in the probable life span of the individual. The magnitude of the effect is fully on a par with that found for other factors, i.e., different Mendelian genes for constitutional vigor, etc.

It has been possible to show by a study of the various sex classifications within the sex-intergrade class that the presence or absence of ovarian or testicular tissue as such is not the primary cause of the difference in the life duration in the type males and females but that the cause is to be found deeper, sex determination and duration of life accompanying each other and resulting from the common cause, chromosome constitution.

The survival curve of the sex-intergrade groups present a limiting curve of duration of life, a constant death rate for each day of age. The curves have different rates of degeneration. To account for this fact it is necessary to assume that for these particular organisms a different organ in the two groups has assumed major significance to life due to the gene complex which causes their differentiation. Recurrent chance environmental and hereditary agents acting on organs generate the type of probability curve observed.

Triploid flies are made up of cells which are one-third larger than the cells of the type flies. It is not without significance to note that such individuals show no greater or less duration of life than do the ordinary flies when both groups have their chromosomes in balance.
ON THE THEORY OF NERVOUS CONDUCTION
Authors: Rashevsky N.
Published: May 2004

Assuming that the propagation of the nervous impulse consists in the excitation of adjacent regions of the nerve by the action current of the already excited region, exact equations for the velocity of such a propagation are established and integrated. The result depends on the assumptions which we make about the laws of excitation. If Hoorweg's law is accepted, it is found that the velocity of propagation decreases exponentially with time, and that there is a limiting distance which the impulse will travel and which cannot be exceeded. If however a set of equations proposed by L. Lapique is assumed to govern the process of excitation, we find that the velocity of propagation asymptotically reaches a constant value.
THE ANALYSIS OF BIOLUMINESCENCES OF SHORT DURATION, RECORDED WITH PHOTOELECTRIC CELL AND STRING GALVANOMETER
Authors: Harvey E. Newton , Snell Peter A.
Published: May 2004

1. The rapid decay of luminescence in extracts of the ostracod crustacean Cypridina hilgendorfii, has been studied by means of a photoelectric-amplifier-string galvanometer recording system.

2. For rapid flashes of luminescence, the decay is logarithmic if ratio of luciferin to luciferase is small; logarithmic plus an initial flash, if ratio of luciferin to luciferase is greater than five. The logarithmic plot of luminescence intensity against time is concave to time axis if ratio of luciferin to luciferase is very large.

3. The velocity constant of rapid flashes of luminescence is approximately proportional to enzyme concentration, is independent of luciferin concentration, and varies approximately inversely as the square root of the total luciferin (luciferin + oxyluciferin) concentration. For large total luciferin concentrations, the velocity constant is almost independent of the total luciferin.

4. The variation of velocity constant with total luciferin concentration (luciferin + oxyluciferin) and its independence of luciferin concentration is explained by assuming that light intensity is a measure of the luciferin molecules which become activated to oxidize (accompanied with luminescence) by adsorption on luciferase. The adsorption equilibrium is the same for luciferin and oxyluciferin and determines the velocity constant.
DETACHMENT OF BACTERIOPHAGE FROM ITS CARRIER PARTICLES
Authors: Hetler D. M. , Bronfenbrenner J.
Published: May 2004

The active substance (phage) present in the lytic broth filtrate is distributed through the medium in the form of particles. These particles vary in size within broad limits. The average size of these particles as calculated on the basis of the rate of diffusion approximates 4.4 mµ in radius. Fractionation by means of ultrafiltration permits partial separation of particles of different sizes. Under conditions of experiments here reported the particles varied in the radius size from 0.6 mµ to 11.4 mµ. The active agent apparently is not intimately identified with these particles. It is merely carried by them by adsorption, and under suitable experimental conditions it can be detached from the larger particles and redistributed on smaller particles of the medium.
ELECTROKINETIC PHENOMENA
Authors: Abramson H. A. , Grossman E. B.
Published: May 2004

1. The conditions are described which are necessary for the comparison of certain types of electrokinetic potentials. An experimental comparison is made of (a) electrophoresis of quartz particles covered with egg albumin; and (b) similar experiments by Briggs on streaming potentials. A slight, consistent, difference is found between the electrophoretic potential and the streaming potential. This difference is probably due to the difference in the protein preparations used rather than to real difference in the electrophoretic and streaming potentials.

2. Data are given which facilitate the measurements and enhance the precision of the estimation of electrical mobilities of microscopic particles.
TEMPERATURE CHARACTERISTIC FOR PRODUCTION OF CO2 BY PHASEOLUS SEEDLINGS
Authors: Crozier W. J. , Navez A. E.
Published: May 2004

The temperature characteristic for respiratory production of CO2 by young seedlings of Phaseolus aureus (Roxb.) is µ = 16,500 calories, 12–21°C., even when the analyses depend upon the use of many seedlings crowded in a small respiration chamber, provided reasonable precautions are taken to avoid injury and to permit proper thermal adaptation. There is evidence of a definite critical temperature at 20–21°. These findings agree quantitatively with those obtained with other similar seedlings, and contradict the results reported by Kurbatov and Leonov (1930); the reasons for this are analysed.
THE FLOCCULATION OF GELATIN AT THE ISOELECTRIC POINT
Authors: Straup Danella
Published: May 2004

The results of this investigation show that a gelatin solution consists of a considerable number of constituents. At a particular temperature, certain gelatin constituents tend to aggregate and to flocculate from solution. When these particular gelatin constituents have completely flocculated, no further change occurs in the system and an apparent equilibrium exists. This is not a dynamic equilibrium between the gelatin flocculate as a whole and the gelatin remaining in the solution but a steady state determined for that system by the temperature.

It is also shown that gelatin can be separated into fractions in which the gelatin constituents are more nearly uniform and tend to flocculate over a much narrower temperature range. It should be possible to obtain a number of fractions in which all of the gelatin would flocculate at a definite temperature. The aggregation of the various gelatin constituents is presumably due to loss of thermal energy, and the temperature at which this occurs must be some function of the mass of the constituent. It is natural to assume, then, that the constituents which flocculate at a given temperature are larger than those which remain in solution at that temperature. Recently, Krishnamurti and Svedberg (1930) have obtained evidence with the ultra-centrifuge that the constituents of a gelatin solution are heterogeneous as to mass, even at a pH value at which there is no tendency toward aggregation.

There is much reason to suppose that the gelatin constituents do not differ very greatly chemically since different fractions have the same refractive index and the same isoelectric point.

The data as a whole are best explained by considering the gelatin constituents to be different degrees of association of the same or very similar molecular structural units. This is in agreement with Sheppard and Houck (1930), who consider that "the molecules of gelatin are fundamentally identical with those of collagen, the difference being only in the degree of association and orientation". Meyer and Mark (1928) have interpreted the x-ray data obtained from collagen as indicating that the micelles of the collagen fiber are built up of main valency chains of anhydro-amino acids. It may be supposed that during peptization of these fibers, the amino acid chains become separated, disorientated, and partially broken up, so producing the heterogeneous system which we know as gelatin. It is evident that the manner in which this breaking-up proceeds depends upon the chemical treatment previous to the peptization process and the gelatin produced from lime-treated collagen would be expected to differ from that from acid-treated collagen.

From the results herein reported it seems evident that the technique of isoelectric flocculation of electrolyte-free gelatin offers a profitable method for the study of gelatin and an extended investigation along these lines should yield much valuable information concerning the nature of gelatin. It is possible that this method may also be extended to other hydrophilic colloids.
THE PHOTOTROPIC SENSITIVITY OF PHYCOMYCES AS RELATED TO WAVE-LENGTH
Authors: Castle E. S.
Published: May 2004

Under the circumstances of experimentation described, the sporangiophores of Phycomyces are found to be most sensitive to stimulation by light in the violet between 400 and 430 mµ. Toward the red, sensitivity falls to nearly zero near 580 mµ, while in the near ultra-violet around 370 mµ, sensitivity is still high. The previous experiments of Blaauw had placed the point of greatest sensitivity some 80 mµ nearer the red end of the spectrum. Because of the known presence in the sporangiophores of Phycomyces of "accessory" pigments, care must be taken in identifying such results with the absorption spectrum of the photosensitive substance.
CRYSTALLINE PEPSIN
Authors: Northrop John H.
Published: May 2004

1. Pepsin solutions which have been completely denatured and inactivated by adjusting to pH 10.5 recover some of their activity when titrated to about pH 5.4 and allowed to stand at 22°C. for 24 to 48 hours.

2. Control experiments show that this inactivation and reactivation are probably not due to the effect of any inhibiting substance.

3. A method of isolation of the reactivated material has been worked out.

4. The reactivated material recovered in this way is a protein with the same general solubility, the same crystalline form, and the same specific proteolytic activity as the original crystalline pepsin.

5. This furnishes additional proof that the proteolytic activity is a property of the protein molecule.
THE COMBINATION OF A STANDARD GELATIN PREPARATION WITH HYDROCHLORIC ACID AND WITH SODIUM HYDROXIDE
Authors: Hitchcock David I.
Published: May 2004

It has been found possible to obtain constant dry weights of sheet gelatin only by drying in vacuo at temperatures below 100°C. for a period of several weeks. Values are given for the ash and nitrogen content, the specific conductivity, and the isoelectric point of a standard gelatin preparation. By the method of E.M.F. measurements of cells without liquid junction, of the type Ag, AgCl, HCl + gelatin, H2, it has been found that this gelatin in 0.1 M HCl combines with a maximum of 9.58 x 10–4 equivalents of H+ and 2.0 x 10–4 equivalents of Cl-. By means of pH measurements with the hydrogen electrode and a KCl junction, the combination curve of this gelatin with H+ from HCl and OH- from NaOH has been determined between pH 1.1 and 12.5.
ANALYSIS OF THE GEOTROPIC ORIENTATION OF YOUNG RATS. IV
Authors: Crozier W. J. , Pincus G.
Published: May 2004

The geotropic orientation of young rats of a closely inbred line P, separated 6 years ago from a stock which gave rise also to the closely inbred lines A and B previously studied, has been measured. The curve connecting orientation-angle with inclination of substratum is in a general way similar to those for A, B, and with them differs markedly from that for race K of totally different ancestry. The variability of the response exhibits similar affinities. Although the orientation-angles are rather close to those obtained with A, the threshold slope for P is that for B; analysis of the curve discloses how this fact is related to the character of the presumptive distributions of thresholds for the respective arrays of tension-receptor units. It is pointed out that these considerations prevent loose comparisons of "geotropic sensitivity" in different lines of rats, but make it plain why comparisons in terms of thresholds for response or of magnitude of response at the same threshold are ineffective. The estimated "number of excitation units," however, is found to correspond to the variability of orientation, and to the manner and extent whereby the dispersions of the measured orientation-angles are governed by the magnitude of the gravitational vector.
THE KILLING OF COLON BACILLI BY ULTRAVIOLET LIGHT
Authors: Wyckoff Ralph W. G.
Published: May 2004

The survival ratios of colon bacilli subjected to several monochromatic ultraviolet radiations follow semilogarithmic straight lines. For each wave length approximate observations have been made of the energy involved in cell destruction. This energy varies somewhat with frequency in the ultraviolet region; it is furthermore nearly one hundred times as great as the amount of X-ray energy required to bring about the same killing.

Preliminary experiments show no measurable difference either in rate of killing or in lethal energy between B. coli and B. aertrycke. Parallel results have already been obtained with X-rays and electrons.

The data from colon bacilli are interpreted in terms of the assumptions employed for X-rays. They indicate that though bacterial death should result from a single quantum absorption, millions more such absorptions seemingly are without injurious effect on cell growth and multiplication. The "sensitive volume" within which, according to this picture, the lethal quantum must be stopped proves to be about the same as that of a single protein molecule. If this is the correct description of the phenomena of ultraviolet killing, it seems strange that the millions of non-deadly quanta absorbed per bacillus should not show themselves by altered growth rates or in other ways. That they apparently do not suggests the inapplicability of the statistical picture. The death rate under this kind of radiation then would be primarily an expression of the relative sensitivities of the bacterial population. Additional experiments are required to determine this question.
INTERMITTENT STIMULATION BY LIGHT
Authors: Hecht Selig , Wolf Ernst
Published: May 2004

On the basis of previous knowledge of the photosensory behavior of Mya it is shown that Talbot's law for the effectiveness of stimulation by intermittent illumination should be valid. Two series of measurements are reported in which the photosensory effects of intermittent and continuous illuminations are compared. The results demonstrate the validity of Talbot's law for Mya.