bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE GROWTH AND DURATION OF LIFE OF CELOSIA CRISTATA SEEDLINGS AT DIFFERENT TEMPERATURES
Authors: Edwards Thomas I. , Pearl Raymond , Gould Sophia A. 
Published: May 2004

Daily measurements of hypocotyl length were made on Celosia cristata seedlings cultured in darkness under aseptic conditions at six constant temperatures between 14.5° and 40.5°C. At 40.5° roots did not penetrate the agar and only the hypocotyls that were supported by the wall of the test tube could be measured.
The growth curves were of the generalized logistic type, but of different degrees of skewness. The degree of symmetry of the growth curves was influenced by temperature. At the lower temperatures the maximal growth rate came relatively late in the grand period of growth; at successively higher temperatures it came progressively earlier.
The mean total time rate of growth (millimeter per diem) was found to be a parabolic function of the temperature.
The maximum rate of growth was found from the curve to be at 30.48°C. The maximum observed rate of growth, and the maximum yield, were found to be at 30°C.
At all temperatures above 14.5° the maximum growth activity fell in the second quarter of the whole growth period. At all temperatures tested other than 30°, and at all parts of the growth cycle, the growth yield as measured by height of hypocotyl at any given equivalent point was less than at 30°.
The total duration of life of the seedlings, and the duration of life after the end of the growth period (intermediate period) were inversely proportional to the mean total growth rate. The observations on Celosia cristata seedlings are thus in accord with the "rate of living" theory of life duration.
The optimal temperature for life duration is the minimum temperature, within the range of these observations.
CRYSTALLINE ACETYL DERIVATIVES OF PEPSIN
Authors: Herriott Roger M. , Northrop John H. 
Published: May 2004

Crystalline pepsin has been acetylated by the action of ketene in aqueous solution at pH 4.07–5.5. As acetylation proceeds the activity decreases, the decrease being more rapid at pH 5.0–5.5 than at 4.0–4.5.
Three acetyl derivatives have been isolated from the reaction mixture and obtained in crystalline form. The crystal form of these derivatives is similar to that of pepsin.
Fractionation and solubility determinations show that these preparations are not mixtures or solid solutions of the original pepsin with an inactive derivative.
A compound which contains three or four acetyl groups and which has lost all of its original primary amino groups can be isolated after short acetylation. It has the same activity as the original pepsin. A second derivative containing six to eleven acetyl groups has also been isolated. It has about 60 per cent of the activity of the original pepsin. A third derivative having twenty to thirty acetyl groups and about 10 per cent of the activity of original pepsin can be isolated after prolonged acetylation. The 60 per cent active derivative on standing in strong acid solution loses some of its acetyl groups and at the same time regains the activity of the original pepsin. The compound obtained in this way is probably the same as the completely active three acetyl derivative obtained by mild acetylation. These results show that acetylation of three or four of the primary amino groups of pepsin causes no change in the specific activity of the enzyme but that the introduction of acetyl groups in other parts of the molecule results in a marked loss in activity.
The solubilities, amino nitrogen content, acetyl content, isoelectric point, and the specific activity have been determined by a variety of methods and found to be different from the corresponding properties of crystalline pepsin. The pH-activity curves, acid and alkali inactivation, and titration curves were not significantly different from the same respective properties of pepsin.
THE LIGHT GROWTH RESPONSE AND THE GROWTH SYSTEM OF PHYCOMYCES
Authors: Castle E. S. , Honeyman A. J. M. 
Published: May 2004

1. The Roscoe-Bunsen law holds for the light growth response of Phycomyces if the time component of stimulation is short. With exposures longer than a few seconds, the reaction time to light is determined by the intensity and not by the energy of the flash.
2. The possible nature of the very long latency in the response to light is considered in terms of the structure of the cell and its mechanism of growth. It is suggested that during the latency some substance produced by light in the protoplasm is transported centrifugally to the cell wall or outermost layer of protoplasm.
3. The total elongation occurring over a period of 1 to 2 hours is independent of flashes of light or temporary darkening. Light acts by facilitating some change already under way in the growth system, and during the principal phase of elongation is not a necessary or limiting factor for growth.
4. Judged by the reaction time, the original sensitivity is restored in the light system following exposure to light in about one-third the time required for equilibrium to be reattained in the growth system.
THE KINETICS OF PENETRATION
Authors: Jacques A. G. 
Published: May 2004

The rate of entrance of H2S into cells of Valonia macrophysa has been studied and it has been shown that at any given time up to 5 minutes the rate of entrance of total sulfide (H2S + S-) into the sap is proportional to the concentration of molecular H2S in the external solution.
This is in marked contrast with the entrance of ammonia, where Osterhout has shown that the rate of entrance of total ammonia (NH3 + NR4+) does not increase in a linear way with the increase in the external concentration of NH3, but falls off. The strong base guanidine also acts thus.
It has been shown that the rate of entrance of H2S is best explained by assuming that it enters by diffusion of molecular H2S through the non-aqueous protoplasmic surface.
It has been pointed out that the simple diffusion requires that the rate of entrance might be expected to be monomolecular. Possible causes of the failure of H2S to follow this relationship have been discussed.
CHEMICAL RESTORATION IN NITELLA
Authors: Osterhout W. J. V. 
Published: May 2004

Cells of Nitella exposed to distilled water lose their ability to produce action currents and to distinguish electrically between sodium and potassium. This ability was quickly restored by exposure to blood plasma deprived of calcium. Human blood and that of the cat, calf, and sheep gave essentially the same results.
The active agents appear to be organic substances.
THE POLARIZATION CAPACITY AND RESISTANCE OF VALONIA
Authors: Blinks L. R. 
Published: May 2004

Alternating current measurements of the effective capacity and resistance of Valonia cells were undertaken to determine whether a static or polarization capacity was responsible for the large slow time curves of counter E.M.F. produced by the flow of direct current. (For this purpose it was necessary that the cells be in the regular state.) With external contacts at the ends of ceils, a large fall of impedance occurs over the frequency range from zero to 20,000 cycles, above which the impedance is low and essentially that of the cell interior.As a first approximation to the cell circuit, a simple series-parallel circuit was employed in the bridge balance, with a resistance setting to represent the cell wall (and protoplasmic leakage), shunting the protoplasmic capacity in series with a resistance (sap plus polarization resistance). Both the capacity and its associated series resistance fall off regularly with frequency, giving curved lines on logarithmic plots against frequency, the slope of the resistance plot being steeper, and approaching that of f–1, although curved to it. These parallel roughly the behavior of a polarizing electrode, which is also shown.Before concluding that the cell's capacity is therefore due to polarization, a further complication of the circuit was considered. This was the effect of the protoplasmic capacity distributed along the wall between the contacts. Both logically and experimentally it was shown that a distributed capacity, as represented by its approximate T-network of resistances and capacities invariant with frequency, could give rise to changes of capacity and series resistance with frequency which simulate to some extent the cellular phenomena.Distributed capacity was therefore reduced in the cells by using shorter air-gaps between the contacts, or abolished by measuring impaled cells, in which the current flow across the protoplasm was entirely radial. These measurements showed a smaller, but still significant change of capacity and of equivalent resistance (in series with it) with frequency, somewhat less than with electrodes, and probably representing the true protoplasmic behavior. It is concluded that the cells display a certain degree of polarization capacity, possibly in parallel with a static capacity invariant with frequency. This might result from an insulating (e.g. lipoid) cell surface, having a residual differential permeability to ions. This structure is consistent with other evidence showing the cells to be chiefly permeable to non-ionized, lipoid-soluble materials, but still displaying electrical effects (conductance, potential difference, polarization) ascribable to ionic mobility.
THE KINETICS OF SAPONIFICATION OF IODOACETIC ACID BY SODIUM HYDROXIDE AND BY CERTAIN ALKALINE BUFFER SOLUTIONS
Authors: Brdička R. 
Published: May 2004

1. The rate of the saponification of iodoacetic acid in sodium hydroxide and alkaline buffer solutions yielding glycollic acid was measured by means of Heyrovský's polarographic method.
2. From the bimolecular velocity constants, increasing with the ionic strength of the solution, the Brönsted factor, F, which characterizes the primary salt effect, was calculated.
3. In the borate buffer solutions the monomolecular constants of the saponification were determined which, at values above the pH of neutralization of boric acid, show a proportionality to the concentration of hydroxyl anions. Below the pH of neutralization of boric acid, they are proportional to the concentration of borate anions.
COMPARATIVE STUDIES ON RESPIRATION
Authors: Gustafson F. G. 
Published: May 2004

1. In the presence of 0.05 per cent dextrose the respiration of Aspergillus niger is increased by NaCl in concentrations of 0.25 to 0.5M, and by 0.5M CaCl2.
2. Stronger concentrations, as 2M NaCl and 1.25M CaCl2, decrease the respiration. The decrease in the higher concentrations is probably an osmotic effect of these salts.
3. A mixture of 19 cc. of NaCl and 1 cc. of CaCl2 (both 0.5M) showed antagonism, in that the respiration was normal, although each salt alone caused an increase.
4. Spores of Aspergillus niger did not germinate on 0.5M NaCl (plus 0.05 per cent dextrose) while they did on 0.5M CaCl2 (plus 0.05 per cent dextrose) and on various mixtures of the two. This shows that a substance may have different effects on respiration from those which it has upon growth.
THE RELATIVE PHYSIOLOGICAL EFFECTS OF ß- AND γ-RAYS UPON THE EGG OF NEREIS
Authors: Redfield Alfred C. , Bright Elizabeth M. 
Published: May 2004

When Nereis eggs are exposed to radiations from a tube of radium emanation, the walls of which absorb all the α-rays, the resulting physiological change is produced by rays having a coefficient of absorption of the order of 23.9 cm.–1
This fact indicates that the physiological effect is due almost exclusively to ß-rays.
The γ-rays alone can produce the reaction. To produce equivalent physiological effects exposure to γ-rays alone must be approximately 60 times as long as exposure to ß- and γ-rays together.
CHANGES IN PROTOPLASMIC CONSISTENCY AND THEIR RELATION TO CELL DIVISION
Authors: Chambers Robert 
Published: May 2004

1. The development of the amphiaster is associated with the formation of two semisolid masses within the more fluid egg substance.
2. The elongation of the egg during cleavage is possibly produced as a consequence of the mutual pressure of these two growing semisolid masses.
3. The division of the egg into two blastomeres consists essentially in a growth, within the egg, of two masses of material at the expense of the surrounding cytoplasm. When all the cytoplasm of the egg is incorporated in these two masses cleavage occurs.
4. After a certain period of time the semisolid masses revert to a more fluid state. In the eggs studied this normally occurs after the cleavage furrow has completed the separation of the two blastomeres. The formation of the furrow, however, may be prevented in various ways, upon which the egg reverts to a single spherical semifluid mass containing two nuclei.
5. An egg mutilated during its semisolid state (amphiaster stage) may or may not revert to a more fluid state. If the more solid state is maintained, the cleavage furrow persists and proceeds till cleavage is completed. If the mutilation causes the egg to revert to the more fluid state the furrow becomes obliterated and a new cleavage plane is subsequently adopted.
6. The nuclei of eggs in the semifluid state are able to alter their positions. In semifluid mutilated eggs the nuclei tend to move to positions which may assure symmetry in aster formation and cleavage.
ADRENALIN IN ANNELIDS
Authors: Gaskell J. F. 
Published: May 2004

1. The sympathetic nervous system and the adjuvant adrenalin-secreting system are found in their earliest form in the annelid kingdom, and consist of cells situated in the central nervous system which are the common ancestors of both, and which are both secretory and nervous in function.
2. These cells are developed in the annelid kingdom parallel with the development of a contractile vascular system, which possesses muscles comparable in physiological actions with the muscle of the vertebrate heart.
3. This vascular muscle is regulated by the processes of the common ancestral cells as well as by their secretory activity.
4. In the primitive form contractile rhythm is an intrinsic property of cardiac muscle; its nerve supply regulates the rhythm, it does not initiate it. The beat is therefore myogenic, not neurogenic.
5. The contractile vascular system of annelids is mainly branchial in function. The vertebrate heart has been derived from it by the growing around of the lateral body folds to form a new ventral surface.
LABYRINTH AND EQUILIBRIUM
Authors: Maxwell S. S. 
Published: May 2004

1. A dogfish from which all six ampullæ have been removed maintains its equilibrium; the righting reactions occur promptly; compensatory movements of the eyes occur in response to rotations in all planes except the horizontal; the compensatory position of the eyes is retained if the animal is held in an abnormal position. Both the static and dynamic functions of equilibrium continue, therefore, after complete removal of all the semicircular canals and all the ampullæ.
2. After complete removal of the otoliths from the vestibules without injury to the ampullæ the animal maintains its equilibrium in the water, rights itself promptly, and makes compensatory motions to rotations in all planes. If held in an abnormal position the compensatory position of the eyes is maintained. Both static and dynamic functions of equilibrium continue.
3. Destruction of both the semicircular canals and the otolith organs completely abolishes all compensatory movements and equilibrium reactions of labyrinthine origin.
4. It is pointed out that these observations do not justify the theory of Mach and Breuer that the ampullæ and semicircular canals are the organs for the dynamic functions of equilibrium, and that the otoliths are the organs for the static functions of equilibrium.
5. The new experiments recorded in this paper show that the ampullæ alone (without the otoliths) suffice for all the dynamic and all the static functions of equilibrium of the ear; and that the otolith organs (without the ampullæ) suffice for all the static and for all the dynamic functions of equilibrium of the ear with the exception of the response to a rotation of the animal in a horizontal plane.
STUDIES ON ENZYME ACTION
Authors: McGuire Grace , Falk K. George 
Published: May 2004

The saccharogenic enzymes present in potato juice were studied. The actions were followed upon the substances present in the juice and upon added sucrose, maltose, and soluble starch.
Sucrase and amylase were found to be present in the juice. No indication of a maltase was obtained.
The sucrase showed optimum conditions for action at pH 4 to 5, the amylase at pH 6 to 7, both upon the starch present in the juice and upon added soluble starch.
The action of a yeast sucrase preparation upon the juice showed the presence of sucrose (or raffinose) in a concentration of the order of magnitude of 1 per cent.
THE PHOTOCHEMICAL NATURE OF THE PHOTOSENSORY PROCESS
Authors: Hecht Selig 
Published: May 2004

1. In order to produce a response in Mya, the minimum amount of light energy required is 5.62 meter candle seconds. This energy follows the Bunsen-Roscoe law for the relation between intensity and time of exposure.
2. The necessary minimum amount of energy varies but little with the temperature; the temperature coefficient for 10°C. is 1.06.
3. In view of these facts it is concluded that the initial action of the light is photochemical in nature. This substantiates the hypothesis previously suggested to account for the mechanism of photoreception.
4. The constant energy requirement for stimulation of Mya shows that the traditional division of animals into those which respond to a constant source of light and those which respond to a rapidly augmented light is without any fundamental significance for sensory physiology.
QUANTITATIVE LAWS IN REGENERATION. I
Authors: Loeb Jacques 
Published: May 2004

1. Equal masses of sister leaves of Bryophyllum calycinum produce equal masses of shoots and roots in equal time and under equal conditions.
2. The mass of shoots and roots produced by different masses of sister leaves in equal time and under equal conditions is approximately in direct proportion to the masses of the leaves.
3. When a piece of stem inhibits the production of shoots and roots in a leaf of Bryophyllum connected with it, the stem gains in mass and this gain in mass equals approximately the mass of shoots and roots the leaf would have produced if it had been detached from the stem.
4. This suggests that the inhibitory influence of the stem upon the formation of shoots and roots in the leaf is due to the fact that the material available for this process naturally flows into the stem.
INTENSITY AND THE PROCESS OF PHOTORECEPTION
Authors: Hecht Selig 
Published: May 2004

1. In the photosensory process of Mya the latent period varies inversely as the intensity of the stimulating light.
2. Quantitative analysis of the data shows that the photochemical effect of the light is a logarithmic function of its intensity, the two variables being related to each other according to the well known "compound interest" law.
3. Comparison with previous experiments demonstrates that the Reciprocity Law of Bunsen and Roscoe applies to the photosensory process not only for the minimum energy required for a response, but for a much greater range of energy application as well.
STUDIES IN THE DYNAMICS OF HISTOGENESIS
Authors: Carey Eben J. 
Published: May 2004

1. The region of most active mitosis per mm. of cross-section in the intestine is the entodermal epithelial tube. The mitotic figures primarily follow the path of a right-handed helix. In one of the twenty embryos the mitotic figures describe the path of a right-handed helix.
2. The region of least active or relatively passive growth per mm. of cross-section is the mesenchyme, derived from the splanchnic mesoderm surrounding the epithelial tube.
3. The rapid expansion, due to epithelial growth in a rotating spiral manner, of the intestinal lumen is greater than the activity manifest in the surrounding mesenchyme. This causes a pressure in the latter resulting in a flattening and elongation of the mesenchymal cells. The successive changes in shape of these cells through the spherical, ellipsoidal, and spindle cellular phases are seen. The mesenchymal wall decreases in thickness, due to tension caused by epithelial tubular dilation.
4. The rotating spiral growth of the epithelial cells causes the formation of a series of mesenchymal cellular and fibrillar concentric rings due to the centripetal force of the former.
5. The circular, smooth muscle cells are differentiated in the outer, more condensed margins of the ring. At these points the developing tensional stresses are greater than within the ring.
6. The inner circular smooth muscle coat is the first one differentiated and is incident to the rapid growth of the epithelial tube in diameter. The former soon tends to restrict the growth of the epithelial tube in diameter. The tube, pursuing the lines of least resistance, grows in length. During the period of rapid growth in length the outer longitudinal muscle coat is in the process of formation.
7. The tensional stresses to which the elongated strained mesenchymal cells are subjected appear to be a dynamic stimulus to smooth muscle differentiation.
8. From this study of a closely graded and progressive series of sections of intestinal development, the conclusion is drawn that muscle tissue is not self-differentiating, in the strict sense of the term, but that the tension of differential growth acts as the stimulus to smooth muscle differentiation.
THE EFFECT OF THE CONCENTRATION OF ENZYME ON THE RATE OF DIGESTION OF PROTEINS BY PEPSIN
Authors: Northrop John H. 
Published: May 2004

1. In certain cases the rate of digestion of proteins by pepsin is not proportional to the total concentration of pepsin.
2. It is suggested that this is due to the fact that the enzyme in solution is in equilibrium with another substance (called peptone for convenience) and that the equilibrium is quantitatively expressed by the law of mass action, according to the following equation.
See PDF for Equation
It is assumed that only the uncombined pepsin affects the hydrolysis of the protein.
3. The hypothesis has been put in the form of a differential equation and found to agree quantitatively with the experimental results when the concentration of pepsin, peptone, or both is varied.
4. Pepsin inactivated with alkali enters the equilibrium to the same extent as active pepsin.
5. Under certain conditions (concentration of peptone large with respect to pepsin, and concentration of substrate relatively constant) the relative change in the amount of active pepsin is inversely proportional to the concentration of peptone and the equation simplifies to Schütz's rule.
6. An integral equation is obtained which holds for the entire course of the digestion (except for the first few minutes) with varying enzyme concentration. This equation is identical in form with the one derived by Arrhenius for the action of ammonia on ethyl acetate.
7. It is pointed out that there are many analogies between the action of pepsin on albumin solutions and the action of toxins on an organism.