bluuebunny/crossref_metadata_2025_split huggingface dataset:
HUMAN GROWTH CURVE
Authors: Davenport Charles B. 
Published: May 2004

The human growth curve shows two (and only two) outstanding periods of accelerated growth—the circumnatal and the adolescent.
The circumnatal growth cycle attains great velocity, which reaches a maximum at the time of birth. The curve of this cycle is best fitted by a theoretical skew curve of Pearson's Type I. It has a theoretical range of 44 months and a standard deviation of 5.17 months. The modal velocity is 10.2 kilos per year.
The adolescent growth cycle has less maximum velocity and greater range in time than the circumnatal cycle. The best fitting theoretical curve is a normal frequency curve ranging over about 10 years with a standard deviation of about 21 months and a modal velocity of 4.5 kilos per year.
The two great growth accelerations are superimposed on a residual curve of growth which measures a substratum of growth out of which the accelerations arise. This probably extends from conception to 55 years, on the average. It is characterized by low velocity, averaging about 2 kilos per year from 2 to 12 years. It is interpreted as due to many growth operations coincident or closely blending in time.
Our curve shows no third marked period of acceleration at between the 3rd and 6th years.
The total growth in weight of the body is the sum of the weight of its constituent organs. In some cases these keep pace with the growth of the body as a whole; great accelerations of body growth are due to great accelerations in growth of the constituent organs. In other cases one of the organs of the body (like the thymus gland) may undergo a change in weight that is not in harmony with that of the body as a whole.
The development of the weight in man is the resultant of many more or less elementary growth processes. These result in two special episodes of growth and numerous smaller, blending, growth operations.
Hypotheses are suggested as to the basis of the special growth accelerations.
SOME PHYSICOCHEMICAL PROPERTIES OF DISSOCIATED SPONGE CELLS
Authors: Galtsoff P. S. , Pertzoff Vladimir 
Published: May 2004

1. The activity of the hydrogen ion, in a system containing 0.00280 mols of NaAc, 0.520 mols of NaCl per liter, and varied amounts of HCl or NaOH has been investigated. The average value of pK' for acetic add in this system is about 4.37.
2. The effect of the addition of various amounts of HCl and NaOH to a system containing 0.00280 mols of NaAc, 0.520 mols of NaCl, and a known number of cells of either Microciona prolifera or Cliona celata was then studied. It was found that in weak acid solutions Microciona behaves as a stronger base than Cliona, the former being practically saturated with base at a pH of 7.5. Similar behavior is shown by suspensions of cells to which no acid or base was added: the cells of Cliona are more acidic than the cells of Microciona.
3. The microscopic examinations of the cells subjected to the treatment with acid or base indicate that the cells of Microciona remain alive down to pH 4.50; the cells of Cliona sustain greater acidity,— a,t pH 3.7 they exhibit no signs of cytolysis. Tests for aggregation of these cells showed that this phenomenon is greatly inhibited even by slightly acid solutions.
4. The conclusion is drawn that the concentration of cells being equal, the suspensions of cells of Microciona and Cliona differ from each other in their physicochemical properties, the comparison being made on suspensions of specified composition.
REGULATION OF THE HYDROGEN ION CONCENTRATION AND ITS RELATION TO METABOLISM AND RESPIRATION IN THE STARFISH
Authors: Irving Laurence 
Published: May 2004

The normal reaction of the cœlomic fluid in Patiria miniata and Asterias ochraceus is pH 7.6, and of the cæca, 6.7, compared with sea water at 8.3, all without salt error correction. A medium at pH 6.7–7.0 is optimum for the cæca for ciliary survival and digestion of protein, and is maintained by carbon dioxide production. The optimum pH found for carbon dioxide production is a true one for the effect of hydrogen ion concentration on the tissue. It does not represent an elimination gradient for carbon dioxide.
Because the normal excised cæca maintain a definite hydrogen ion concentration and change their internal environment toward that as an optimum during life, there exists a regulatory process which is an important vital function.
AMPHOTERIC BEHAVIOR OF COMPLEX SYSTEMS
Authors: Stearn Allen E. 
Published: May 2004

Conductivities of sulfanilic acid, lysin, and mixtures of the two were made over a wide pH range, the pH being adjusted by means of phosphate buffers. The actual conductivities of the sulfanilic acid, the lysin, and the mixture were calculated. The difference between the conductivity of the mixture and the sum of the conductivities of the components alone passes through a maximum at a pH theoretically calculable as the isoelectric point of the system.
Certain applications of the results are made to the explanation of the behavior of living tissues.
THE OXIDATION-REDUCTION POTENTIAL OF THE LUCIFERIN-OXYLUCIFERIN SYSTEM
Authors: Harvey E. Newton 
Published: May 2004

The oxidation-reduction potential of the Cypridina luciferin-oxyluciferin system determined by a method of "bracketing" lies somewhere between that of anthraquinone 2-6-di Na sulfonate (Eo' at pH of 7.7 = –.22) which reduces luciferin, and quinhydrone (Eo' at pH of 7.7 = +.24), which oxidizes luciferin. Systems having an Eo' value between –.22 and +.24 volt neither reduce oxyluciferin nor oxidize luciferin. If the luciferin-oxyluciferin system were truly reversible considerable reduction and oxidation should occur between –.22 and +.24. The system appears to be an irreversible one, with both "apparent oxidation" and "apparent reduction potentials" in Conant's sense. Hydrosulfites, sulfides, CrCl2, TiCl3, and nascent hydrogen reduce oxyluciferin readily in absence of oxygen but without luminescence.
Luminescence only appears in water solution if luciferin is oxidized by dissolved oxygen in presence of luciferase. Rapid oxidation of luciferin by oxygen without luciferase or oxidation by K3Fe(CN)6 in presence of luciferase but without oxygen never gives luminescence.
THE STAGES OF THE PEPTIC HYDROLYSIS OF EGG ALBUMIN
Authors: McFarlane Jennie , Dunbar Violet E. , Borsook Henry , Wasteneys Hardolph 
Published: May 2004

1. Most of the products of the peptic hydrolysis of albumin, about 85 per cent of the total N, are primary in the sense that they arise directly from the protein molecule, and undergo no further hydrolysis.
2. A slow secondary hydrolysis, involving about 15 per cent of the total N, occurs in the proteose and simpler fractions primarily split off.
3. Acid metaprotein in peptic hydrolysis arises as a result of the action of acid. It is not an essential stage in the hydrolysis of undenatured albumin.
4. Acid metaprotein is hydrolyzed by pepsin more slowly under comparable conditions than undenatured albumin.
PHOSPHATE ION AS A PROMOTER CATALYST OF RESPIRATION
Authors: Lyon Charles J. 
Published: May 2004

The active component of phosphate solutions, in relation to promoter action on oxidising enzymes, is the PO4''' ion. This is shown by the demonstration of a hyperbolic relationship between per cent production of CO2 (of Elodea) and pPO4, the measure of the phosphate ion potential. This is consistent with the rate of respiration as affected by changing pPO4 through change of total phosphate concentration while pH is kept constant. The equation for this relationship is
(CO2 – a) (pPO4 – b)n = K
where a, b, n, and K are constants and n = 1.
The same relationship to phosphate ion concentration, expressed by the equation
(Activity of enzyme) (pPO4)n = K,
where n and K are constants and n varies from 1 to 6 under different conditions, appears to hold for some other enzyme actions, including those of peroxidase and pancreatic lipase.
TIME RELATIONS OF GROWTH
Authors: Brody Samuel 
Published: May 2004

Growth curves consist, in all cases, of two major segments. The first major segment is, in the case of higher animals and plants, made up in turn of several (probably five) shorter segments during each of which growth takes place at a constant percentage rate. The transitions between the successive stages are abrupt, the abruptness being of the order of metamorphosis in cold blooded animals.
It has been made clear in the first paper of this series that the time rate of growth following the major inflection declines at a constant percentage rate.
The junction between the two major segments occurs at puberty in animals and flowering in plants.
The two major segments are not symmetrical about the major inflection. The slope of the segment following the inflection is always less than the slope of the segment preceding the inflection. The major inflection does not occur in the center of the growth curve.
The instantaneous rate of growth at the beginning of growth is of the order of 100–200 per cent per day (i.e. the body weight is doubled in from 7 to 17 hours). It may be mentioned that 2 months after conception the rate of growth in man is only 8 per cent per day. This is contrary to all the published statements. Thus, Minot concluded that growth begins at 1000 per cent per day; Jackson concluded that in man, growth during the 1st month takes place at 57.5 million per cent per month; during the 2nd month 990 per cent per month; during the 3rd month 390 per cent per month (8 per cent per day is only 240 per cent per month). The reason for the discrepancy between the values derived, by the method adopted by the writer, and the values given in the literature is explained by Fig. 1.
THE KINETICS OF EXOSMOSIS OF WATER FROM LIVING CELLS
Authors: McCutcheon Morton , Lucke Baldwin 
Published: May 2004

1. The rate of exosmosis of water was studied in unfertilized Arbacia eggs, in order to bring out possible differences between the kinetics of exosmosis and endosmosis.
2. Exosmosis, like endosmosis, is found to follow the equation
See PDF for Equation,
in which a is the total volume of water that will leave the cell before osmotic equilibrium is attained, x is the volume that has already left the cell at time t, and k is the velocity constant.
3. The velocity constants of the two processes are equal, provided the salt concentration of the medium is the same.
4. The temperature characteristic of exosmosis, as of endomosis, is high.
5. It is concluded that the kinetics of exosmosis and endosmosis of water in these cells are identical, the only difference in the processes being in the direction of the driving force of osmotic pressure.
THE ACTIVATION OF STARFISH EGGS BY ACIDS
Authors: Lillie Ralph S. 
Published: May 2004

1. Comparison of the rates of activation of unfertilized starfish eggs in pure solutions of a variety of parthenogenetically effective organic acids (fatty acids, carbonic acid, benzoic and salicylic acids, chloro- and nitrobenzoic acids) shows that solutions which activate the eggs at the same rate, although widely different in molecular concentration, tend to be closely similar in CH. The dissociation constants of these acids range from 3.2 x 10–7 to 1.32 x 10–3.
2. In the case of each of the fourteen acids showing parthenogenetic action the rate of activation (within the favorable range of concentration) proved nearly proportional to the concentration of acid. The estimated CH of solutions exhibiting an optimum action with exposures of 10 minutes (at 20°) lay typically between 1.1 x 10–4 M and 2.1 x 10–4 M (pH = 3.7–3.96), and in most cases between 1.6 x 10–4 M and 2.1 x 10–4 M (pH = 3.7–3.8). Formic acid (CH = 4.2 x 10–4 M) and o-chlorobenzoic acid (CH = 3.5 x 10–4 M) are exceptions; o-nitrobenzoic acid is ineffective, apparently because of slow penetration.
3. Activation is not dependent on the penetration of H ions into the egg from without, as is shown by the effects following the addition of its Na salt to the solution of the activating acid (acetic, benzoic, salicylic). The rate of activation is increased by such addition, to a degree indicating that the parthenogenetically effective component of the external solution is the undissociated free acid. Apparently the undissociated molecules alone penetrate the egg freely. It is assumed that, having penetrated, they dissociate in the interior of the egg, furnishing there the H ions which effect activation.
4. Attention is drawn to certain parallels between the physiological conditions controlling activation in the starfish egg and in the vertebrate respiratory center.
MICRURGICAL STUDIES IN CELL PHYSIOLOGY
Authors: Chambers Robert , Pollack Herbert 
Published: May 2004

I. Cytoplasm.
1. The normal cytoplasmic pH, colorimetrically determined, of the starfish eggs in the unfertilized, fertilized, and first and second cleavage stages is 6.7 ± 0.1.
2. Cytolysis lowers the pH to a value 5.5 ± 0.1.
3. The cytolyzed material in time assumes the pH of its environing sea water.
4. The acid due to mechanical injury can also be detected in the environment of the egg.
5. Injury to the cytoplasm unaccompanied by visible disintegration causes an increase in acidity which is quickly neutralized.
II. Germinal Vesicle.
6. The intranuclear pH, colorimetrically determined, of the immature Asterias egg is 7.5 ± 0.1.
7. Injury to the nucleus does not change its pH.
8. The spherical nuclear remnant which persists after injury gradually assumes the pH of its environment.
III. Plasmalemma.
9. A dye to which the cell is normally impermeable can penetrate through a tear in the surface from an environment more acid than normal. This may be due to a difference in the formation of the plasmalemma in a normal and an acid medium.
THE KINETICS OF DARK ADAPTATION
Authors: Hecht Selig 
Published: May 2004

1. Data are presented for the dark adaptation of four species of animals. They show that during dark adaptation the reaction time of an animal to light of constant intensity decreases at first rapidly, then slowly, until it reaches a constant minimum.
2. On the assumption that at all stages of adaptation a given response to light involves a constant photochemical effect, it is possible to describe the progress of dark adaptation by the equation of a bimolecular reaction. This supposes, therefore, that dark adaptation represents the accumulation within the sense cells of a photosensitive material formed by the chemical combination of two other substances.
3. The chemical nature of the process is further borne out by the fact that the speed of dark adaptation is affected by the temperature. The velocity constant of the bimolecular process describing dark adaptation bears in Mya a relation to the temperature such that the Arrhenius equation expresses it with considerable exactness when µ = 17,400.
4. A chemical mechanism is suggested which can account not only for the data of dark adaptation here presented, but for many other properties of the photosensory process which have already been investigated in these animals. This assumes the existence of a coupled photochemical reaction of which the secondary, "dark" reaction is catalyzed by the products of the primary photochemical reaction proper. This primary photochemical reaction itself is reversible in that its main products combine to form again the photosensitive material, whose concentration controls the behavior of the system during dark adaptation.
STUDIES ON ENZYME ACTION
Authors: Noyes Helen Miller , Lorberblatt I. , Falk K. George 
Published: May 2004

The ester-hydrolyzing actions of trout extracts at different hydrogen ion concentrations were studied. It was pointed out that the behavior was similar to that found with various tissue and tumor materials and that similar relations hold.
Glycerol solutions extracted somewhat larger amounts of active enzyme material from trout than did water and sodium chloride solutions, although the differences were not large. Evidence was presented for the existence of a so called "coenzyme."
STUDIES ON THE AMOUNT OF LIGHT EMITTED BY MIXTURES OF CYPRIDINA LUCIFERIN AND LUCIFERASE
Authors: Stevens Kenneth P. 
Published: May 2004

1. A photometric method was devised for measuring the intensities of light emitted per cc. of hiciferin solution and calculating the amount of light emitted per gm. of dried Cypridina powder. A total of 128 runs was made and the data are incorporated in this report.
2. The maximum amount of light emitted from 1 gm. of powder under the experimental conditions was 0.655 lumens. Different samples of powder vary greatly in amount of light production.
3. When the concentration of substrate is doubled, nearly twice as much light is emitted, or an average ratio 2C/C of 1.86. Calculations of total light emissions per gm. of powder at different concentrations indicate that slightly more light is produced from the smaller concentrations. The maximum amount of light was produced by the solutions made with neutral sea water and averaged 0.445 lumens. The least light was obtained from solutions in distilled water saturated with hydrogen. The technique allows too rapid spontaneous oxidation prior to the saturation with hydrogen. The maximum amount of light from such experiments was only 0.077 lumens. Acid sea water solutions subsequently neutralized gave an average maximum of 0.386 lumens per gm. of powder per second.
4. When the concentration of enzyme is doubled, approximately the same amount of light is produced by both concentrations, although the stronger concentrations are slightly less effective than weaker ones. This undoubtedly is due to the colloidal nature of the enzyme and is a function of surface rather than of mass. In dilute solutions greater dispersion probably allows for greater adsorption to the surface of the enzyme. The average maximum amount of light produced in the series of enzyme experiments is of the magnitude 0.56 lumens per gm. of powder.
THE SWELLING OF ISOELECTRIC GELATIN IN WATER
Authors: Northrop John H. , Kunitz M. 
Published: May 2004

It has been assumed that gelatin consists of a network of an insoluble material enclosing a solution of a more soluble material.
The swelling of gelatin is therefore primarily an osmotic phenomena in that the water tends to diffuse in owing to the osmotic pressure of the soluble material. This osmotic pressure is opposed by the elasticity of the insoluble constituent, and equilibrium results when these two pressures are equal.
The rate of the entrance of water should then obey Poiseuille's law, provided the variable terms are expressed as functions of the volume. Equations have been derived in this way which agree quite well with the experimental curves and which predict the proper relation between the size and shape of the block and the rate of swelling. They lead to a value for the rate of flow of water through gelatin which has been checked by direct measurement.
The mechanism assumed predicts that at a higher temperature and under conditions such that the water has to pass through collodion before reaching the gelatin, the experiment should follow the same course as that of osmosis discussed previously. This was also found to be the case.
The slow secondary increase in swelling is ascribed to fatigue of the elastic properties of the gelatin. The rate of this secondary swelling should therefore be independent of the size of the block, in contrast to the rate of primary swelling which is inversely proportional to the size. It can further be shown that this secondary swelling should be proportional to the square root of the time, and also that with large blocks at higher temperatures the entire swelling should be of this secondary type. These predictions have also been found to be true.
UDDER SIZE IN RELATION TO MILK SECRETION
Authors: Gowen John W. , Tobey Elmer R. 
Published: May 2004

The results herein presented furnish exact critical evidence for the conclusion that the most of the milk is present as such in the udder of dairy cattle at the time of milking. The amount of milk which may be secreted during milking cannot, on the basis of these results, be over 20 per cent of the milk yield of the cow.
The results show clearly that the size of the udder measures closely the amount of milk which the cow is able to secrete.
The results indicate that about 1/5 of a pound of secreting tissue is necessary for the secretion of a pound of milk during a period of 15 hours. The weight of the udder during the period that the cow is dry appears to be between 6 and 8 pounds.
THE EFFECT OF TEMPERATURE UPON SOME OF THE PROPERTIES OF CASEIN
Authors: Pertzoff Vladimir 
Published: May 2004

1. The investigations dealing with the properties of casein as an acid were reviewed.
2. The solubility of uncombined casein in water was measured at 5°C. and found to be 0.70±0.1 mg. of N per 100 gm. of water.
3. Robertson's solubility measurements of casein in bases at various temperatures were recalculated and found to agree well with more recent measurements.
4. By combining the observations of several investigators, as well as the author's measurements of the solubility of casein, in base, at various temperatures, the following conclusions were reached:
(a) The solubility of casein in base is affected by the temperature in a discontinuous manner.
(b) There exist two ranges of temperature, one, extending from about 21° to 37°C. and the other from about 60° to 85°C. where the solubility of casein in base is practically independent of temperature.
(c) From 37° to 60° the equivalent combining weight of casein rises from the value 2100 to about 3700 gm.
5. By comparing the values of base bound by 1 gm. of casein at the two temperature ranges with a constant, the value of base necessary to saturate the same amount of casein, it was found that the latter value is a common multiple of the former values, indicating the stoichiometric nature of the effect of temperature.
SOME ASPECTS OF BIOELECTRICAL PHENOMENA
Authors: Osterhout W. J. V. 
Published: May 2004

It is pointed out that there are great advantages in using single cells instead of tissues in the study of bioelectrical phenomena.
Certain bioelectrical phenomena are discussed in relation to the structure of protoplasm.
Under certain circumstances measurements of potential differences may enable us to determine what ions enter the protoplasm.
Under suitable conditions we are able to ascertain the potential differences across the protoplasm at single points, instead of being obliged merely to measure the differences between two points.