bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECT OF RENNIN UPON CASEIN
Authors: Pertzoff Vladimir 
Published: May 2004

The properties of the paracasein and casein preparations studied are compared in Table VI.
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I. Casein retains its characteristic solubility in NaOH: (1) after being exposed to a high degree of alkalinity during its preparation, (2) when recovered from partially hydrolyzed solutions in NaOH, and (3) after being kept for a prolonged time at the isoelectric point at 5°C.
II. It follows from I, that: (1) paracasein is not identical to casein modified by an excess of alkali, and that (2) this protein was not produced from casein by a partial hydrolysis of the latter in presence of NaOH.
THE NATURE OF THE IONIZABLE GROUPS IN PROTEINS
Authors: Simms Henry S. 
Published: May 2004

Analysis of the experimental titration curves shows that gelatin contains acid groups with dissociation indices at pH 2.9 to 3.5 corresponding quantitatively with the content in dicarboxylic amino acids; and that the acidic group at pH 9.4 in egg albumin agrees with the amount of tyrosine.
The amounts of histidine and lysine present in both these proteins agree quantitatively with basic groups at pH 6.1 and pH 10.4 to 10.6, respectively.
However, the quantity of the arginine group (pH 8.1) in these proteins is considerably less than the amount of arginine found on hydrolysis. This deficiency is compensated (quantitatively with gelatin and approximately with egg albumin) by a basic group at pH 4.6.
The structure of this "4.6 group" should be similar to aniline and cytosine in consisting of an amino group on a conjugated unsaturated (perhaps cyclic) system. It would appear that the 4.6 group is disrupted on hydrolysis, producing arginine, and may be referred to as "prearginine."
The presence of prearginine in proteins, instead of the full amount of arginine, has an important effect on the properties. Otherwise the isoelectric point of gelatin would be 8.0 (instead of 4.7) and of egg albumin 6.6 (instead of 4.8), and the titration curves would be quite different in shape between pH 4 and 10.
Deamination of gelatin produces no decrease in prearginine, arginine, or histidine groups, but removes nearly all of the lysine group.
THE INFLUENCE OF TEMPERATURE ON THE PHOTOSENSORY LATENT PERIOD
Authors: Hecht Selig 
Published: May 2004

1. The effect of temperature on the photosensory latent period in Pholas dactylus is accurately described by the Arrhenius equation when µ = 18,300.
2. The adequacy of this equation has already been found for two other photosensitive animals, Mya and Ciona, which are very similar in behavior to Pholas. The value of µ is different for each of the three species studied.
3. This is taken to mean that though the organization of the receptor process is the same for the three species, the chemical materials concerned are very likely different.
SIGNIFICANCE OF THE CHEMICAL COMPOSITION OF THE SECRETING AND DRY MAMMARY GLAND TO MILK SECRETION
Authors: Gowen John W. , Tobey Elmer R. 
Published: May 2004

The results herein presented furnish exact critical evidence for one more stage in milk secretion. Cows producing up to 30 pounds of milk at one milking are shown to have the lactose equivalent of all this milk in the udder when milking commences. The average excess of lactose found in the udder after subtracting the amount necessary for the contained milk is equal to 2.1 pounds. This represents the milk retained in the udder when the cow is believed to be dry. These conclusions are further supported by the fact that no sugar is found in the udder in the quiescent state.
The study of the total composition of the udder as fat, ash, nitrogen, and lactose, and of the contained milk shows that there is a large excess of fat, ash, and nitrogen in proportion to that necessary for milk formation. The excess of udder lactose over the milk lactose is much less.
The lactose would therefore appear to be formed from some element in the blood, probably dextrose, only as needed for the formation of milk.
The composition of the dry udder is quite different in certain respects from that of the actively secreting gland. It builds up a fat reserve of a quite different Reichert-Meissl number from that of butter-fat. It has no sugar, its ash content is reduced, and the nitrogen content is like that of the secreting gland.
THE PREARGININE IN EDESTIN AND ITS RESISTANCE TO HYDROLYSIS
Authors: Simms Henry S. 
Published: May 2004

The titration data of edestin show that all the arginine found on hydrolysis exists in this protein as "prearginine."
The extra ionizable groups of histidine, lysine and tyrosine are free in the quantities found on hydrolysis. Part of the extra carboxyl groups of aspartic and glutamic acids are bound as amides, and 50 per cent are bound in some other manner (perhaps anhydride) leaving only about 6 per cent of these groups free to ionize in edestin.
The prearginine in edestin is not converted into arginine on hydrolysis with pepsin up to 18 per cent (of the total hydrolysis). In more highly hydrolyzed solutions it is not possible to detect such a conversion, due to high buffering. Complete hydrolysis however converts prearginine into arginine which can be isolated.
Hydrolyzed edestin promotes the growth of sarcomatous fibroblasts about equally well whether 5, 14 or 18 per cent hydrolyzed.
SYNERESIS AND SWELLING OF GELATIN
Authors: Kunitz M. 
Published: May 2004

1. When solid blocks of isoelectric gelatin are placed in cold distilled water or dilute buffer of pH 4.7, only those of a gelatin content of more than 10 per cent swell, while those of a lower gelatin content not only do not swell but actually lose water.
2. The final quantity of water lost by blocks of dilute gelatin is the same whether the block is immersed in a large volume of water or whether syneresis has been initiated in the gel through mechanical forces such as shaking, pressure, etc., even in the absence of any outside liquid, thus showing that syneresis is identical with the process of negative swelling of dilute gels when placed in cold water, and may be used as a convenient term for it.
3. Acid- or alkali-containing gels give rise to greater syneresis than isoelectric gels, after the acid or alkali has been removed by dialysis.
4. Salt-containing gels show greater syneresis than salt-free gels of the same pH, after the salt has been washed away.
5. The acid and alkali and also the salt effect on syneresis of gels disappears at a gelatin concentration above 8 per cent.
6. The striking similarity in the behavior of gels with respect to syneresis and of gelatin solutions with respect to viscosity suggests the probability that both are due to the same mechanism, namely the mechanism of hydration of the micellæ in gelatin by means of osmosis as brought about either by diffusible ions, as in the presence of acid or alkali, or by the soluble gelatin present in the micellæ. The greater the pressures that caused swelling of the micellæ while the gelatin was in the sol state, the greater is the loss of water from the gels when the pressures are removed.
7. A quantitative study of the loss of water by dilute gels of various gelatin content shows that the same laws which have been found by Northrop to hold for the swelling of gels of high concentrations apply also to the process of losing water by dilute gels, i.e. to the process of syneresis. The general behavior is well represented by the equations:
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and
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where P1 = osmotic pressure of the soluble gelatin in the gel, P2 = stress on the micellæ in the gelatin solution before setting, Ke = bulk modulus of elasticity, Vo = volume of water per gram of dry gelatin at setting and Ve = volume of water per gram of gelatin at equilibrium.
THE PHOTOTROPIC EXCITATION OF LIMAX
Authors: Crozier W. J. , Cole W. H. 
Published: May 2004

The photic orientation of Limax creeping geotropically upon a vertical plate is such that the phototropic vector determining the angular deflection ß from the vertical path is proportional to log I. This is proved by the fact that with horizontal illumination tan ß is directly proportional to log I; with non-horizontal light rays from a small source the ratio
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is directly proportional to log I (where A = the angle between light rays and the path of orientation), the vector diagram of the field of excitation being in this case not a right-angled triangle.
A GLASS ELECTRODE APPARATUS FOR MEASURING THE pH VALUES OF VERY SMALL VOLUMES OF SOLUTION
Authors: MacInnes D. A. , Dole Malcolm 
Published: May 2004

A glass electrode apparatus is described with which pH measurements can be made with as small volumes as 2 drops (about 0.14 cc.) of solution.
Using this apparatus the change of pH of the vacuolar sap of Nitella, due to the penetration of brilliant cresyl blue, has been readily followed. The sap and the dye have been found to poison the usual type of hydrogen electrode.
RESEMBLANCES BETWEEN THE ELECTROMOTOR VARIATIONS OF RHYTHMICALLY REACTING LIVING AND NON-LIVING SYSTEMS
Authors: Lillie Ralph S. 
Published: May 2004

1. The electromotor variations of pure iron wires, arranged to react rhythmically with nitric acid, are recorded and described.
2. Resemblances between these variations and those of rhythmically reacting living tissues (especially the heart) are pointed out and discussed.
THE CATALYTIC EFFECT OF DYES ON THE OXYGEN CONSUMPTION OF LIVING CELLS
Authors: Barron E. S. Guzman , Hoffman L. A. 
Published: May 2004

From the experiments described in this paper and in those previously published it can be concluded that dyes which can be reversibly oxidized and reduced, act as catalysts for some oxidative processes taking place in the living cells, as is manifested by an increase in their oxygen consumption.
It has been found that the catalytic power of the dyes on the oxygen consumption of starfish eggs (mature, unfertilized) is conditioned by two factors: the reduction potential of the dye and the permeability of the cell surface. Dyes whose E'o is towards the positive side of the aerobic reduction potential of the starfish eggs have a maximum catalytic effect. This catalytic power decreases as the E'o becomes more negative than the reduction potential of the cell and becomes nil beyond certain limits. When a dye cannot penetrate into the cell, its effect is greatly diminished as in this case only those oxidative processes taking place at the outer surface of the cell can be activated.
Whether a dye can act as a catalyst or not is dependent on whether the normal consumption of oxygen by the cell is slower or quicker than the oxidation activated by the dye. The speed of this activation is correlated to (1) the speed at which the dye is reduced by the cell, and (2) the speed at which the leuco-dye is oxidized by the atmospheric oxygen. If one of these two processes is slower than the normal respiration, the dye cannot increase the rate of oxygen consumption (phenol indophenol at low concentrations which is kept reduced by the cell is very slowly reoxidized by atmospheric oxygen, on the other hand safranin and neutral red which are not reduced by the cell or at least too slowly reduced, though rapidly reoxidized by air). It will depend on these two reactions velocities whether a dye will act as catalyst (methylene blue and dyes with similar E'o which are quickly reduced by the cell and the leuco-dyes of which are relatively quickly reoxidized). Though this relationship between the reduction potential of the dyes and its catalytic power would seem in contradiction with the well known thermodynamic assumption that there is in general no distinct relationship between the potential and velocity of the reaction, we have pointed out from the literature some of the various experiments where one does recognize this connection.
THE INFLUENCE OF THE QUANTITY OF NUTRITION UPON THE GROWTH OF THE SUCKLING MOUSE
Authors: MacDowell E. C. , Gates W. H. , MacDowell C. G. 
Published: May 2004

Under usual conditions, the growth of the suckling mouse is limited by the quantity of mother's milk available.
As this limitation is removed the growth curve approaches a parabola, which is abruptly interrupted at the end of the second week, when the natural process of weaning begins.
THE OSMOTIC PRESSURE OF CONCENTRATED SOLUTIONS OF GELATIN IN EQUILIBRIUM WITH SOLUTIONS OF MAGNESIUM CHLORIDE
Authors: Adair G. S. , Callow E. H. 
Published: May 2004

The osmotic pressures and the membrane equilibrium of chloride ions have been determined for solutions of gelatin in equilibrium with solutions of magnesium chloride containing from 4.0 to 9.0 equivalents per litre.
The pressures increase more rapidly than the concentration, an effect represented by a high value of the term "b" in van der Waals' equation p (V – b) = RT. Calculations made by a thermodynamical formula which makes allowances for deviations from the ideal solution laws show that the high value of "b" is not due to an unequal distribution of diffusible ions.
The theory that the high values of the hydration estimated from viscosity formulae account for the magnitude of "b" has been examined and the conclusion has been reached that the term "b" for gelatin as well as for haemoglobin is considerably larger than the volume of the protein hydrate.
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 cells of Nitella show that azure B in the form of free base penetrates the vacuoles and raises the pH value of the sap to about the same degree as the free base of the dye added to the sap in vitro, but the dye salt dissolved in the sap does not alter the pH value of the sap. It is concluded that the dye penetrates the vacuoles chiefly in the form of free base and not as salt.
The dye from methylene blue solution containing azure B free base as impurity penetrates and accumulates in the vacuole. This dye must be azure B in the form of free base, since it raises the pH value of the sap to about the same extent as the free base of azure B dissolved in the sap in vitro. The dye absorbed by the chloroform from methylene blue solution behaves like the dye penetrating the vacuole. These results confirm those of spectrophotometric analysis previously published.
Crystal violet exists only in one form between pH 5 and pH 9.2, and does not alter the pH value of the sap at the concentrations used. It does not penetrate readily unless cells are injured.
A theory of "multiple partition coefficients" is described which explains the mechanism of the behavior of living cells to these dyes.
When the protoplasm is squeezed into the sap, the pH value of the mixture is higher than that of the pure sap. The behavior of such a mixture to the dye is very much like that of the sap except that with azure B and methylene blue the rise in the pH value of such a mixture is not so pronounced as with sap when the dye penetrates into the vacuoles.
Spectrophotometric measurements show that the dye which penetrates from methylene blue solution has a primary absorption maximum at 653 to 655 mµ (i.e., is a mixture of azure B and methylene blue, with preponderance of azure B) whether we take the sap alone or the sap plus protoplasm.
These results confirm those previously obtained with spectrophotometric measurements.
STUDIES ON CRYSTALLINE UREASE
Authors: Tauber Henry , Kleiner Israel S. 
Published: May 2004

1. Crystalline urease is not inactivated by trypsin in the absence of a gum. In fact, the presence of trypsin alone in aqueous solutions of urease has an action similar to that of gum, that is, it acts as a "protective colloid" for urease.
2. Crystalline urease is inactivated by trypsin in the presence of a gum. This occurs with great rapidity if purified (crystalline) trypsin is used.
3. If trypsin is added to urease a considerable time before the addition of gum no inactivation of the urease takes place.
4. The suggested explanation is that an inhibitive group of the urease molecule ("antitrypsin") may combine with trypsin to form an irreversible inactive trypsin compound, which cannot attack the urease but has unchanged ureolytic power. This compound cannot be formed if gum is present because the gum has united with a portion of the urease molecule; the tryptic power is thus unimpaired and urease is then digested. This speaks for the protein nature of urease.
THE SENSIBILITY OF THE SUN-FISH, LEPOMIS, TO MONOCHROMATIC RADIATION OF LOW INTENSITIES
Authors: Grundfest Harry 
Published: May 2004

1. A test is proposed of the hypothesis that visual purple is the photosensitive substance concerned in dim vision. It is based on the fact that fish visual purple is different from that of other vertebrates. If the hypothesis is correct, the fish dim-visibility function should be different from that of other vertebrates and should be determined by the absorption spectrum of its visual purple.
2. A new method is described for obtaining the visibility function of fish, in quantitative terms. It depends on the measurement of the least amounts of various spectral energies which will produce a visual orienting response to the displacement of a constant background.
3. Data are presented on thirteen animals. It is shown that the maximum of the visibility function is identical with the maximum of the absorption spectrum of fish visual purple. The shapes of the visibility curves obtained are, however, variable and different from that of the absorption spectrum.
4. The possibility that Lepomis visual purple is different from that of other fish is ruled out by a series of measurements which confirm the results of Koettgen and Abelsdorff on other fish.
5. Reasons are given for the conclusion that there are present in Lepomis special conditions which distort the visibility curve out of true agreement with that predictable from the absorption spectrum of its visual purple. The suggestion is made that the presence of light absorbing, but not light sensitive, pigments is responsible for this distortion. One of these pigments may perhaps be carotin while the second is unspecified.
THE TEMPERATURE CHARACTERISTIC OF RESPIRATION OF AZOTOBACTER
Authors: Lineweaver Hans , Burk Dean , Horner C. Kenneth 
Published: May 2004

The temperature characteristic of respiration of Azotobacter vinelandii possesses a constant value of 19,330 ± 165 over the temperature range 20–30°C. This value is independent of pH, oxygen tension, age of culture, and other factors within the limits studied.
The optimum temperature of respiration is 34–35°C., with limits at about 10° and 50°C.
ELECTROKINETIC PHENOMENA
Authors: Abramson Harold A. 
Published: May 2004

1. By combining the theories of Smoluchowski, Debye and Hückel, and Henry it is possible to state explicitly (making necessary assumptions) under what conditions the following simple rule should be valid for proteins:
In solutions of the same ionic strength, the electric mobilities of the same protein at different hydrogen ion activities should be proportional to the number of hydrogen (hydroxyl) ions bound.
2. Data of Tiselius and of the writer confirm this rule for (a) egg albumin, (b) serum albumin, (c) deaminized gelatin and gelatin, and (d) casein.
3. On the basis of the confirmed theory the titration curves of certain proteins are predicted from their mobilities.
4. It is shown that when certain proteins are adsorbed by quartz the apparent dissociation constant of the adsorbed protein is practically unchanged. The mass law must also be valid at the phase boundary.
5. The facts of paragraphs (1) to (4) are discussed in connection with the mechanism of (a) protein adsorption, (b) enzyme activity, (c) immune reactions, (d) the calculation of the electric charge of cells, and (e) criteria of surface similarity.
PROTOPLASMIC POTENTIALS IN HALICYSTIS
Authors: Blinks L. R. 
Published: May 2004

The potential difference across the protoplasm of impaled cells of two American species of Halicystis is compared. The mean value for H. Osterhoutii is 68.4 mv.; that for H. ovalis is 79.7 mv., the sea water being positive to the sap in both.
The higher potential of H. ovalis is apparently due to the higher concentration of KCl (0.3 M) in its vacuolar sap. When the KCl content of H. Osterhoutii sap (normally 0.01 M or less) is experimentally raised to 0.3 M, the potential rises to values about equal to those in H. ovalis.
The external application of solutions high in potassium temporarily lowers the potential of both, probably by the high mobility of K+ ions. But a large potential is soon regained, representing the characteristic potential of the protoplasm. This is about 20 mv. lower than in sea water.
The accumulation of KCl in the sap of H. ovalis is apparently not due to the higher mobility of K+ ion in its protoplasm, since the electrical effects of potassium are practically identical in H. Osterhoutii, where KCl is not accumulated.
ON THE MEASURE OF EXCITABILITY
Authors: Blair H. A. 
Published: May 2004

Recent time-intensity data by Rushton (1932) on the sciatic nerve of the frog are shown to provide additional support to the writer's suggestion (1932, a) that integrals of the equation
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where V is the applied voltage, p is the local excitatory process and K and k are constants adequately represent the just effective direct current stimuli when the threshold value of p is made a linear function of the voltage of the form h ± α V where h and α are constants.
The measurement of excitability is discussed and it is shown that the criteria for "true" measurements are not likely to be found by the agreement of the data with canonical time-intensity functions as suggested by Lapicque (1931) but rather in the establishing of standard experimental conditions. These conditions may permit the use of chronaxie as a measure of excitability, but it seems more likely that the constant k of the above equation will have to be adopted. There is sufficient evidence to cast considerable doubt on the validity of any conclusions drawn from the existing measurements of chronaxie although those derived through a particular technique may be valid. The problem requires a thorough experimental investigation in terms of integrals of the above equation.