bluuebunny/crossref_metadata_2025_split huggingface dataset:
ON THE DYNAMICS OF PHOTOSYNTHESIS
Authors: Osterhout W. J. V. , Haas A. R. C. 
Published: May 2004

Minute amounts of photosynthesis in marine plants can be accurately measured by adding a little phenolphthalein to the sea water, and observing changes in the color of the indicator. In the case of fresh water aquatics bicarbonates are added.
By this method it is found that Ulva which has been kept in the dark begins photosynthesis as soon as it is exposed to sunlight and that the rate steadily increases until a constant speed is attained.
This may be explained by assuming that sunlight decomposes a substance whose products either catalyze photosynthesis or enter directly into the reaction.
Quantitative theories are developed in order to account for the facts.
THE ANTAGONISM BETWEEN THYROID AND PARATHYROID GLANDS
Authors: Uhlenhuth Eduard 
Published: May 2004

From the facts stated in this paper it is evident that the thymus gland of mammals contains a substance which is capable of producing tetany when fed to the larvæ of certain species of salamanders (Ambystoma opacum and Ambystoma maculatum). As long as the larvæ have not developed their own thymus glands, they are able, by means of some mechanism, to counterbalance the tetanic action of the thymus substance introduced in their food. When, however, the secretion from their own thymus glands is added to the thymus material introduced with the food, this mechanism of preventing tetany becomes inadequate and tetany ensues. In the larva of a third species of salamander, Ambystoma tigrinum, this mechanism will prevent tetany even when the larvæ are fed on thymus.
In mammals the parathyroids are known to prevent tetany and are supposed either to absorb the tetany-producing substance and thus prevent its action or to change it into another non-toxic substance. It is at least probable that in the amphibians the parathyroids play the same rôle. Larvæ of anuran amphibians, which develop their parathyroids soon after hatching, never show tetanic convulsions if they are fed on thymus, but in certain species of salamanders, whose parathyroids develop only during metamorphosis, the larvæ invariably have tetanic convulsions upon thymus feeding, while the metamorphosed animals never show tetany.
But in addition to the parathyroids the salamanders must possess still another mechanism which during the larval period inhibits the production of tetany by the animal's own thymus glands. In the larvæ of Ambystoma opacum and Ambystoma maculatum this mechanism is sufficient only to prevent tetany from the animal's own thymus, while in the larvæ of Ambystoma tigrinum it is capable of preventing tetany even when the larvæ are fed with thymus.
If the thymus is the organ by whose action tetany is produced, we can understand why tetany in human beings occurs far more frequently in children than in adults, since in the latter the thymus gland is replaced, at least to a great extent, by connective tissue. The relation of thymus to tetany may also possibly explain the occurrence of tetany during pregnancy; while the parathyroids of the mother may be sufficient to prevent tetany from her largely atrophied thymus, they may not be sufficient to prevent tetany from the excess of thymus substance furnished by the fetus to the blood of the mother.
THE LAW CONTROLLING THE QUANTITY OF REGENERATION IN THE STEM OF BRYOPHYLLUM CALYCINUM
Authors: Loeb Jacques 
Published: May 2004

1. A method is given which allows us to measure the influence of the mass of a leaf upon the quantity of shoots regenerated in an isolated piece of stem. This method consists in isolating a piece of stem with only two leaves left at the basal node and then splitting the stem lengthwise so that each half has one basal leaf. By leaving one leaf intact while the size of the sister leaf is reduced, the influence of the mass of the leaf upon the quantity of shoots regenerated by the stem can be measured.
2. This method has yielded the result that the mass of shoots regenerated at the apex of such a piece of stem increases under equal conditions and in equal time with the mass of the leaf, and is approximately proportional to the mass of the leaf.
3. Such an influence of the mass of the leaf upon the mass of shoots produced by the stem is only intelligible on the assumption that the growth of the regenerating shoot occurs at the expense of material furnished by the basal leaf.
4. This assumption is supported by two facts: first, that in the dark this influence of the leaf disappears more or less completely; and, second, that a leaf attached to the base of a regenerating stem after some time weighs markedly less than does a sister leaf completely detached from the stem, but otherwise under equal conditions.
5. This latter fact that a leaf when attached to the base of an excised piece of stem wilts more rapidly than when completely isolated is the reason that the proportionality between mass of a basal leaf and mass of shoot regenerated at the apex of an isolated piece of stem cannot always be demonstrated with the same degree of accuracy as the proportionality between the mass of completely isolated leaves and the mass of shoots they produce.
6. The material furnished by the leaf to the stem is not restricted to water but includes also the solutes, since not only the fresh weight but also the dry weight of the shoot regenerated by a piece of stem increases with the mass of the leaf attached to the base of the stem; and since not only the water contents but the dry weight of a leaf attached to the base of an excised piece of stem diminish when compared with the dry weight of a completely detached sister leaf.
7. The mass of shoots produced by an isolated piece of stem without leaf is small and almost negligible compared with the mass of shoots produced by the same piece of stem when a leaf of sufficient mass is attached to the base of the stem.
THE PHOTIC SENSITIVITY OF CIONA INTESTINALIS
Authors: Hecht Selig 
Published: May 2004

1. Ciona possesses two means of responding to an increase in the intensity of illumination. One is by means of a local reaction; the other is by a retraction reflex of the body as a whole.
2. The "ocelli" are not photoreceptors. The photosensitive area is in the intersiphonal region containing the neural mass. This area contains no pigment.
3. The reaction time to light is composed of a sensitization period during which Ciona must be exposed to the light, and of a latent period during which it need not be illuminated in order to react to the stimulus received during the sensitization period.
4. The duration of the reaction time varies inversely as the intensity. Analysis shows the latent period to be constant. The relation between the sensitization period and the intensity follows the Bunsen-Roscoe rule.
5. During dark adaptation the reaction time is at first large, then it decreases until a constant minimum is reached.
6. A photochemical system consisting of a reversible reaction is suggested in order to account for the phenomena observed. This system includes a photosensitive substance and its precursor, the dynamics of the reaction following closely the peculiarities of the photosensitivity of Ciona.
7. It is shown that in order to produce a reaction, a constant ratio must be reached between the amount of sensitive substance broken down by the stimulus and the amount previously broken down.
8. From the chemical system suggested certain experimental predictions were made. The actual experiments verified these predictions exactly.
9. The results obtained with regularly repeated stimulation not only fail to show any basis for a learning process or for the presence of a "higher behavior," but follow the requirements of the photochemical system suggested before.
COMPARATIVE STUDIES ON RESPIRATION
Authors: Gustafson F. G. 
Published: May 2004

1. In concentrations which are high enough to produce any effect, formaldehyde, ether, and acetone cause an increase, followed by a decrease, in the rate of respiration.
2. 3.65 per cent ether, which causes an increase with certain cultures, produces only a decrease with others.
3. The reaction producing an increase in the respiration with 7.3 per cent ether is a reversible process, while the reaction producing the decrease is not reversible.
4. 0.5 per cent caffeine produces only a decrease in respiration while a saturated solution causes an increase, which is followed by a decrease.
COMPARATIVE STUDIES ON RESPIRATION
Authors: Brooks Matilda Moldenhauer 
Published: May 2004

1. In all the concentrations of ether studied (from 0.037 to 7.3 per cent) there is an increase in the rate of respiration of Bacillus subtilis followed by a decrease.
2. In 7.3 per cent ether in tap water there is an extraordinary increase in the output of CO2 (amounting to 50 times the normal). This does not occur when 0.85 per cent NaCl is added, which indicates antagonism between ether and NaCl.
3. Ether is toxic in low concentrations (0.037 to 1.1 per cent) and high concentrations (3.65 to 7.3 per cent) but in intermediate concentrations (1.1 to 3.65 per cent) stimulates growth.
COMPARATIVE STUDIES ON RESPIRATION
Authors: Thomas Helen Stillwell 
Published: May 2004

These experiments show that 7.3 and 3.65 per cent ether solutions cause an increase in respiration followed by a decrease. The results agree with those of Haas on Laminaria, of Gustafson on higher fungi, and of Mrs. Brooks on bacteria.
They do not agree with the theory of Verworn that anesthesia is a kind of asphyxia and that it decreases respiration.
COMPARATIVE STUDIES ON RESPIRATION
Authors: Irwin Marian 
Published: May 2004

1. The experiments on frog tadpoles show that with 0.15, 0.37, and 0.55 per cent ether solutions there is a decrease in CO2 output. The effect is reversible. With these concentrations the breathing movements and body movements remained normal during the experiment. In 3.65 and 7.3 per cent ether there is a decrease of respiration followed by an increase which in turn is followed by a decrease. The increase may reach about three times the normal rate. The increase in the CO2 output is accompanied by the peeling of the skin. The effect is irreversible.
2. Experiments on an aquatic insect, Dineutes assimilis Aube, show that in 7.3 per cent ether there is a decrease followed by an increase which in turn is followed by a decrease. There is no apparent disintegration of structures in the organism accompanying the increase. The effect is irreversible.
3. The experiments on frog eggs with 7.3 per cent ether show a result similar to that found in aquatic insects.
4. Experiments on Fundulus embryos show that with 0.73 per cent ether there is a reversible decrease in the rate of CO2 production. In 3.65 per cent ether there is a temporary decrease followed by an increase, after which the rate begins to fall off. In 7.3 per cent ether there is an immediate increase amounting to 307 per cent which is followed by a decrease. The increase in the 3.65 and 7.3 per cent ether is accompanied by irreversible changes leading to death. The decrease found in 0.73 per cent ether is not sufficient to cause narcosis, as is shown by experiments on which the same decrease is produced by lowering the temperature.
5. These experiments show that narcosis is not due to asphyxia. The action of anesthetics is due to some other cause than the effect on respiration.
There is a difference between the animals studied and the plants described in this series of articles, since in animals the increase in the CO2 output is accompanied by irreversible changes leading to death, while this is not necessarily the case in plants. The reversible (narcotic) action of ether on the animals studied was accompanied by a decrease in the carbon dioxide output; in plants this is not ordinarily the case.
These facts are of considerable interest, but their interpretation must be left to future investigation.
THE PHYSIOLOGICAL BASIS OF MORPHOLOGICAL POLARITY IN REGENERATION. I
Authors: Loeb Jacques 
Published: May 2004

1. In Bryophyllum calycinum two apical leaves suppress the shoot formation in all the dormant buds situated basally from the leaf; one apical leaf suppresses the shoot formation in the basal buds situated in the same half of the stem where the leaf is, and, if one-half of the petiole of such a leaf is removed, the growth of basal buds in one quadrant of the stem is suppressed.
2. This inhibitory influence of a leaf upon shoot formation in the basal part of a stem is diminished or disappears when the mass of the leaf is reduced below a certain limit.
3. The inhibitory influence of an apical leaf upon the growth of shoots in horizontally suspended stems is greater when the leaf is on the upper than when it is on the lower side of the stem.
4. All these facts suggest the possibility that the inhibitory influence of the leaf upon shoot formation is due to inhibitory substances secreted by the leaf and carried by the sap from the leaf towards the base of the stem.
5. An apical leaf accelerates root formation in the basal part of a stem and this accelerating effect increases with the mass of the leaf.
6. This inhibitory influence of a leaf upon shoot formation and the favoring influence upon root formation in the more basally situated parts of the stem is one of the factors determining the polar character of regeneration.
RELATION BETWEEN THYROID GLAND, METAMORPHOSIS, AND GROWTH
Authors: Uhlenhuth Eduard 
Published: May 2004

1. Two substances are involved in amphibian metamorphosis as studied in Ambystoma opacum: first, iodine, which is taken up by the food, and second, an excretor substance, which is evolved during the processes of growth and serves to induce the excretory function of the thyroid gland.
2. This explains why in larvæ, whose metamorphosis is inhibited by lack of iodine, growth is checked at the time when metamorphosis should occur; for at this time the excretor substance commences to act and this results, if iodine is absent, in the excretion by the thyroid of toxic substances which cause the breakdown of proteins and consequently a decrease in size of the larvæ.
3. Larvæ whose metamorphosis is inhibited by extirpation of the thyroid or by the hereditary lack of a thyroid (as is the case in Typhlomolge) can grow normally, since in them the action of the excretor substance cannot result in the excretion by the thyroid of a toxic growth-inhibiting substance.
4. At low temperature less excretor substance is produced than at high temperature during an equal rate of growth; therefore larvæ kept at low temperature reach a larger size than larvæ kept at high temperature, before they metamorphose.
AMPHOTERIC COLLOIDS
Authors: Loeb Jacques 
Published: May 2004

1. A method is given by which the amount of equivalents of metal in combination with 1 gm. of a 1 per cent gelatin solution previously treated with an alkali can be ascertained when the excess of alkali is washed away and the pH is determined. The curves of metal equivalent in combination with 1 gm. of gelatin previously treated with different concentrations of LiOH, NaOH, KOH, NH4OH, Ca(OH)2, and Ba(OH)2 were ascertained and plotted as ordinates, with the pH of the solution as abscissæ, and were found to be identical. This proves that twice as many univalent as bivalent cations combine with the same mass of gelatin, as was to be expected.
2. The osmotic pressure of 1 per cent solutions of metal gelatinates with univalent and bivalent cation was measured. The curves for the osmotic pressure of 1 per cent solution of gelatin salts of Li, Na, K, and NH4 were found to be identical when plotted for pH as abscissæ, tending towards the same maximum of a pressure of about 325 mm. of the gelatin solution (for pH about 7.9). The corresponding curves for Ca and Ba gelatinate were also found to be identical but different from the preceding ones, tending towards a maximum pressure of about 125 mm. for pH about 7.0 or above. The ratio of maxi mal osmotic pressure for the two groups of gelatin salts is therefore about as 1:3 after the necessary corrections have been made.
3. When the conductivities of these solutions are plotted as ordinates against the pH as abscissæ, the curves for the conductivities of Li, Na, Ca, and Ba gelatinate are almost identical (for the same pH), while the curves for the conductivities of K and NH4 gelatinate are only little higher.
4. The curves for the viscosity and swelling of Ba (or Ca) and Na gelatinate are approximately parallel to those for osmotic pressure.
5. The practical identity or close proximity of the conductivities of metal gelatinates with univalent and bivalent metal excludes the possibility that the differences observed in the osmotic pressure, viscosity, and swelling between metal gelatinates with univalent and bivalent metal are determined by differences in the degree of ionization (and a possible hydratation of the protein ions).
6. Another, as yet tentative, explanation is suggested.
THE SELECTIVE ACTION OF NICOTINE ON THE CENTRAL NERVOUS SYSTEM OF THE SQUID, LOLIGO PEALII
Authors: Moore A. R. 
Published: May 2004

1. In specimens of freshly hatched squid, Loligo pealii, nicotine acts upon the cerebral ganglia alone.
2. After 1 minute in the nicotine solution 1:500,000, the latent period for the mantle spasm is independent of the time spent in the solution.
3. The mantle spasm is conditioned by a chemical reaction, since the temperature coefficient of the process has a magnitude of about 2.8.
4. The velocity of the process which brings about the mantle spasm varies as the cube root of the concentration of the nicotine.
AMPHOTERIC COLLOIDS
Authors: Loeb Jacques 
Published: May 2004

1. When we plot the values of osmotic pressure, swelling, and viscosity of gelatin solutions as ordinates over the pH as abscissæ, practically identical curves are obtained for the effect of monobasic acids (HCl, HBr, HNO3, and acetic acid) on these properties.
2. The curves obtained for the effect of H2SO4 on gelatin are much lower than those obtained for the effect of monobasic acids, the ratio of maximal osmotic pressures of a 1 per cent solution of gelatin sulfate and gelatin bromide being about 3:8. The same ratio had been found for the ratio of maximal osmotic pressures of calcium and sodium gelatinate.
3. The curves representing the influence of other dibasic and tribasic acids, viz. oxalic, tartaric, succinic, citric, and phosphoric, upon gelatin are almost identical with those representing the effect of monobasic acids.
4. The facts mentioned under (2) and (3) permit us to decide between a purely chemical and a colloidal explanation of the influence of acids on the physical properties of gelatin. In the former case we should be able to prove, first, that twice as many molecules of HBr as of H2SO4 combine with a given mass of gelatin; and, second, that the same number of molecules of phosphoric, citric, oxalic, tartaric, and succinic acids as of HNO3 or HCl combine with the same mass of gelatin. It is shown in the present paper that this is actually the case.
5. It is shown that gelatin sulfate and gelatin bromide solutions of the same pH have practically the same conductivity. This disproves the assumption of colloid chemists that the difference in the effect of bromides and sulfates on the physical properties of gelatin is due to a different ionizing and hydratating effect of the two acids upon the protein molecule.
THE RESPIRATORY RATE OF THE SCIATIC NERVE OF THE FROG IN REST AND ACTIVITY
Authors: Moore A. R. 
Published: May 2004

1. With the indicator method of Haas, the rates of carbon dioxide production have been measured in the case of the sciatic nerve, various parts of the brain, and the sartorius muscle of the frog. The rate of respiration of the sciatic nerve is from 10 to 30 per cent of that of the other tissues, varying somewhat with the individual.
2. Stimulation of the sciatic nerve with induction shocks sufficient to induce tetanus of the muscle does not increase the output of carbon dioxide from the sciatic nerve, even if continued as long as 30 minutes. Sartorius muscle used as a control showed a marked increase in carbon dioxide production upon relaxation after contraction resulting from such stimulation.
3. These facts indicate that the nerve impulse does not depend upon processes leading to the production of carbon dioxide.
THE NATURE OF THE LATENT PERIOD IN THE PHOTIC RESPONSE OF MYA ARENARIA
Authors: Hecht Selig 
Published: May 2004

The latent period in the response of Mya to illumination varies inversely as the duration of the exposure to which it is subjected. The reciprocal of the latent period, measuring the velocity of the process which underlies it, is a linear function of the exposure period. Since the duration of the exposure represents the amount of photochemical activity, it is concluded that the substances formed at that time act to catalyze a chemical reaction which determines the duration of the latent period.
This explanation is in accord with the previous work on the photochemical reaction and with the effect of temperature on the latent period. As a result of the combined investigations there is presented a concrete hypothesis for the mechanism of photic reception in Mya.
THE EFFECT OF TEMPERATURE ON THE LATENT PERIOD IN THE PHOTIC RESPONSE OF MYA ARENARIA
Authors: Hecht Selig 
Published: May 2004

1. The effect of temperature on the reaction time of Mya to light is mainly confined to the latent period. The sensitization period, representing a photochemical process, is changed comparatively little.
2. The relation between the latent period and the temperature is adequately expressed by the Arrhenius equation, for temperatures below 21°C. Above this temperature, the latent period becomes increasingly longer than is required by the Arrhenius formula when µ = 19,680.
3. These deviations, occurring above the highest environmental temperature of Mya, are explained on the assumption that the principal product formed during the latent period is inactivated by heat.
4. Calculation of the velocity of the hypothetical inactivation reaction at different temperatures shows that it also follows the Arrhenius rule when µ = 48,500. This value of µ corresponds to those generally found for spontaneous inactivations and destructions.