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Results of the Archbold Expeditions | Behavior and ecological notes on some ants from south-central Florida Полный текст
1944
Schneirla, T. C. (Theodore Christian),
Comparative morphology and phylogeny of the suborder Hexagrammoidei and related taxa (Pisces: Scorpaeniformes)
1944
Shinohara, G. (Hokkaido Univ., Hakodate (Japan). Faculty of Fisheries)
The present study was made in order to clarify the phylogeny of the hexagrammoids and related taxa, and to establish a natural classification system based on phylogenetic considerations. For the analysis of phylogenetic relationships, the cladistic approach was adopted. Initially, morphological characters, including osteological, myological and nervous system features of all hexagrammoid and 36 other scorpaeniform genera were investigated. The polarity of each character was determined by comparison with basal acanthopterygians, fifty-three characters being selected and used for estimating relationships. Secondly, morphological variations of all of the species belonging to Hexagrammos were examined, 10 characters being used for inference of their relationships. The polarity of each character was determined by outgroup comparison. The dispersal route of each hexagrammoid species was proposed on the basis of present distributions. The synapomorphic value of some further characters was examined by reference to the reconstructed phylogeny
Показать больше [+] Меньше [-]The effect of cloddiness of soils on their susceptibility to wind erosion
1944
Van Doren, C.E.
Since the percentage of soil aggregates, approximately 2 mm or less in size, as determined by this method, is the critical point determining the susceptibility of soils to wind action at the ground velocities normally encountered, the process of sieving could be reduced to one sieving to separate the two categories of clod size. This would greatly reduce the amount of time and labor needed to sieve the samples, making it possible to run a great many more samples. The complete sieving can be used where a study of detailed change in clod structure is desired. Analyses of clod structure carried out before and after tillage and seeding operations throughout the season gives a good evaluation of the effect of the various tillage and seeding implements on clod structure. These studies have a practical application in providing a means whereby the susceptibility of land to wind erosion can be determined in advance of the blow season and measures taken to prevent wind erosion. Usually much less damage is done to the land and crop where blowing is prevented rather than where emergency measures are taken after blowing has started.
Показать больше [+] Меньше [-]Effect of boron concentration in the nutrient solution on the soluble and insoluble nitrogen fractions of spinach
1944
Scripture, P.N. | McHargue, J.S.
1. Spinach plants were grown in sand cultures with boron supplied in the nutrient solution at the following rates: 0.25, 0.50, 1.00, and 5.00 p.p.m. 2. The soluble nitrogen was extracted from the fresh plant material with 50% ethyl alcohol and the percentages of soluble and insoluble or protein nitrogen determined. 3. As the boron concentration of the nutrient solution was increased, the rate of protein synthesis tended to increase.
Показать больше [+] Меньше [-]Estudos sôbre a anemia produzida em cães por benzoato de estradiol Полный текст
1944
W. O. Cruz | R. Pimenta de Mello | E. M. da Silva
A anemia que se processa em caes quando se administra grandes doses de benzoato de estradiol, nao parece ser produzida por processes conhecidos de destrui?ao intra-organica. Esta substantia paraliza os fenomenos de rege¬nerate hematica, parece interferir por processo desconhecido na fisiologia sanguinea, produz graves lesoes na rede circulatoria que irriga a mucosa do intestino, principalmente jejuno, ocasipnando nesse orgao «extravasamento variavel de sangue, fator seguramente coadjuvante na formação da anemia.<br>The characteristic findings in the pathological picture presented by 60 dogs when administered large doses of estradiol benzoate subcutaneously in an oil vehicle are: thrombocytopenia, aplastic anemia, which follows a brief latent period, intestinal tract haemorrhages, haemorrhagic lesions occurring principally in the mucosa of the jejunum, followed by prostration and death generally within 1 to 3 weeks. Irregular findings are leucocytosis, purpuric skin lesions, visceral haemorrhages and pyoid bone marrow. The total circulating hemoglobin was determined in 9 dogs before and after the anemia was established, thus verifying the total hemoglobin loss. The blood loss through intestinal haemorrhages during the observation period was determined by benzidine test. The quantity of hemoglobin recovered from the feces in the form of hematin varied between 30 and 70% of the total hemoglobin which disappeared from the circulation. In order to ascertain the degree of intra-organic blood destruction the bilirubin eliminated in the urine of dogs with gall-bladder renal type of fis¬tula was determined daily and these values compared with those obtained for normal animals. The blood destruction as measured by this method was practically nil. An attempt was made to determine whether the presence of large quan¬tities of blood in the intestine might exert a paralyzing effect on the regene¬ration of hemoglobin in dogs rendered anemic through haemorrhage. Ne¬gative results were obtained. Estradiol benzoate administered to dogs during the period of hematic regeneration which occurs in the recovery stage of ane-mia produced by acetyl-phenyl hydrazine demonstrated that the estradiol in¬terferes but little when the regenerative processes have already begun. Repeated transfusions given during the stage of acute anemia practi¬cally do not affect the period of survival. The authors conclude that the main action of estradiol benzoate on the blood physiology of dogs is still obscure. The anemia is not produced by the intra-organic destruction of hemoglobin by known processes and doubtless the blood loss through the intestinal haemarrhages constitutes an important ac¬cessory factor in the mechanism of bringing out this anemia.
Показать больше [+] Меньше [-]The nutritive value of South African feeding stuffs. II. Digestible nutrients and metabolizable energy of lucerne hay at different planes of intake for sheep Полный текст
1944
In an experiment consisting of three periods the digestibility and metabolizable energy content of lucerne hay were determined with each of five mature Merino wethers at the following daily levels of intake, corresponding to the three periods of the experiment: I. 600 grams, II. 800 grams, and III. 1,000 grams. Whilst the differences in the coefficients of digestibility and metabolizable energy content of the lucerne hay fed in periods I and III, respectively, were, in general, found to be insignificant, the hay fed in period II was digested significantly better and contained significantly more metabolizable energy than the hay fed in either of the other two periods. These variations in digestibility and metabolizable energy content are considered to have been caused chiefly by the observed differences in chemical composition - protein, cellulose, and lignin contents - of the lucerne hays consumed in the several periods.
Показать больше [+] Меньше [-]The effect of nitrogen upon the response of cotton and oats to phosphorus
1944
Coleman, R.
The effect of nitrogen upon the response of cotton and oats to phosphorus in the case of Mississippi soils was determined by greenhouse and field experiments in which different rates of nitrogen was applied with varying amounts of phosphorus. There was a definite relationship between the amount of nitrogen available to cotton and oats and their response to phosphorus. Cotton and oats gave only a slight response to phosphorus which was applied with small amounts of nitrogen, but both crops gave a high response to phosphorus which was applied with large amounts of nitrogen. Plants receiving adequate amounts of nitrogen not only respond better to phosphorus, but they also require larger amounts of it. These results partially explain why many crops do not respond better to phosphorus on southern soils which are low in this element, and they suggest that as long as nitrogen remains a limiting element in these soils, nonlegumes will not respond well to phosphate fertilizer.
Показать больше [+] Меньше [-]Potassium response of various crops on a high-lime soil in relation to their contents of potassium, calcium, magnesium, and sodium
1944
Bower, C.A. | Pierre, W.H.
The K response of seven different crops grown on a K-deficient high-lime soil of the Webster series was determined in the greenhouse, using two rates of K fertilization. The crops were analyzed for K, Ca Mg, and Na in order to determine if the variations in the K response of the different crops on high-lime soils might be explained by differences in their normal absorption of Ca, Mg, and Na in relation to K. Large responses to K fertilization were obtained with corn and sorghum, whereas only slight to moderate responses were obtained with flax, oats, and soybeans. Sweet clover gave no response and that of buckwheat was negative. Of the various crops studied, only flax and oats absorbed appreciable amounts of Na. It appears that these crops respond but little to K fertilization because the Na which they absorb substitutes for K in the plant and thereby lowers the crop demand for K. In the case of those crops which absorb only small amounts of Na, it was found that their K responsiveness on the high-lime soil studied varied with their normal contents of Ca and Mg in relation to K. Sweet clover and buckwheat, which gave no K response, are crops which ordinarily use large amounts of Ca and Mg in relation to K, whereas the highly responsive crops, corn and sorghum, normally use small amounts. Soybeans occupy an intermediate position as regards K response and contents of Ca and Mg. These results are explained on the basis that (a) K absorption by crops on high-lime soils is repressed by high concentrations of Ca and Mg in the soil solutions, and (b) that those crops which require considerable amounts of Ca and Mg for normal growth show low response to K fertilization because they lower the ratios of Ca and Mg to K in the soil solution sufficiently to reduce or remove the repressive effects of Ca and Mg on K absorption.
Показать больше [+] Меньше [-]Utilization of plant residues for the production of artificial manures
1944
Martin, J.P. | Wang, Y.
Several artificial manures were prepared from organic residues by the composting process. At various intervals during decomposition, samples of the composts were analyzed for moisture, ash, ammonia nitrate, total nitrogen, pH, and approximate chemical composition. The temperature of each compost was recorded at frequent intervals and the dry weight of the organic material lost during decomposition was determined. The quality of the artificial manures produced was studied by greenhouse and field tests, which were supplemented by laboratory nitrification and fungus culture tests. The results are summarized as follows: 1. The fatty and waxy substances, water-soluble organic matter hemicelluloses, and cellulose underwent extensive decomposition in all the composts. 2. The extent of the lignin decomposition depended greatly upon the chemical nature of the plant materials used. The lignins in straw and cornstalks decomposed only slightly, whereas those in timothy hay, clover hay, and cow manure showed great decomposition. 3. The crude protein increased greatly in the oat straw + inorganic salts and the cornstalks + inorganic composts and slightly in the oat straw + clover hay compost. It decreased slightly in cow manure and lowmoor peat + timothy hay composts and to a considerable extent in the leaves + timothy hay compost. 4. For every 1,OOO pounds of organic residue used for composting, approximately 1 ton of artificial manure was produced. 5. The greenhouse and field studies demonstrated the production from cornstalks of a high quality artificial manure comparable to composted cow manure within a period of 3 months. Good quality products were prepared within 4 to 6 months from cereal straw. Resistant materials, such as salt-grass hay and woody residues, required much longer periods for proper decomposition. Tree and shrub trimmings and other woody materials should not be mixed with ordinary plant refuse because of the slowness with which they decompose. Such products should be built into a special manure pile and be allowed to decompose for a longer time. Composts from peat and leaves should be considered only as soil conditioners. They will, however, make high quality manures if reinforced with inorganic fertilizer. The residual effect of the composts produced from cow manure, cornstalks, and cereal straw was much greater than that of inorganic fertilizer. 6. Nitrification and fungus culture tests confirmed the results of the greenhouse and field tests.
Показать больше [+] Меньше [-]Estudos sôbre o pneumococo: 4a. nota - Influência do pH do meio sôbre a formação da cápsula pelo pneumococo Influence of pH of the medium on the formation of the capsule by pneumococcus Полный текст
1944
J. Guilherme Lacorte | Mario Santos
<abstract language="eng">One of the features of pneumococcus which has deserved the attention of investigators is the capsule. Since Pasteur, Chamberland and Roux (1881) several functions have been ascribed to it as well as peculiar properties. In the present paper, we take into consideration one only aspect of this problem; it is the relationship which there possibly may be between acidity of the culture medium and the power of capsule formation by pneumococcus. As it is known, this germ requires for its development 7.8 as an optimum pH, but maintains its biological activities down to 5.6. These variations do not take place without large alterations, particularly of the capsule, not only from the morphological but also from the chemical viewpoint. The diameter of the mucous envelopment of the pneumococcus decreases in proportion to the increase of acidity down to its complete extinction. This fact has been regarded by investigators as a biological feature inhe¬ring to the germ itself and as proceeding of self-defense. In an acid medium the existing capsule is destroyed and the germ does not produce it again; consequently, acidity inhibits the formation of the capsule. We tried to check how this phenomenon comes to pass and to elucidated it. As we know, the fundamental compound of the pneumococcus capsule is mucin. In the first place, we experimented the action of acidity on same in the following manner: Mucin extracted from bovine submaxillary gland is precipitated by HC1 at a determined concentration degree; the mucin dissolves again and precipi¬tates in function of this concentration. This property of mucin (solubility in acid medium) modifies a little the interpretation of the mechanism of disappearance of the capsule from the said germ in the culture medium. Indeed: The acidification of the medium consecutive to the growth of pneumococcus reduces the dimensions of the capsule until causing its com¬plete disappearance; but on transferring this strain to new optimum cultiva¬ting conditions the capsule appears again exhuberantly, at times as anteriorly, although with biased virulence. Linking these two facts we draw the following conclusions: Pneumo¬coccus does not lose its capacity of capsule formation in an acid medium; but mucin, whilst being produced, is entirely dissolved in this medium by the aid of acidity; we venture to state that, in spite of medium acidity, the capacity of capsule production is a constant feature of pneumococcus and that the disappearance of the capsule does not depend on the pneumococcus in itself when it produces smooth colonies, but on the chemical properties of mucin, mainly on its solubility in acid medium.
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