No abstract

No abstract

Sodium chlorate is gaining recognition as one of the most effective chemical means now available for the control of perennial weeds and many experiment stations are distributing recommendations for its use. In spite of the proved effectiveness of this chemical as an herbicide, results in the hands of growers are too frequently unsatisfactory. Recommended methods of application may also involve serious fire hazards and the costs have been prohibitive for any but small areas. Greater efficiency in the use of sodium chlorate should follow a better understanding of its action and of the way in which it enters and moves within the plant. The present paper is a contribution toward the solution of the latter problem. The common practice in the use of chlorate is to apply the material as a spray to the foliage of the growing plant. The greater effectiveness of chlorate when compared with other herbicides which are equally active in killing the exposed portions of the plants has been ascribed to a downward translocation of the herbicide in the stem and roots of the plant. Crafts (3)' has shown that a mechanism for such penetration is present in field bindweed (Convolvulus arvensis L.) growing in dry soil, in which case, as the soil approaches the permanent wilting point, the cells of the roots develop a considerable water-absorbing power. When the tips of the vines of such plants were cut under eosin solution, the dye was drawn several feet into the roots as the tracheal sap, relieved of tension at the top, was absorbed by the living cells of the root. When herbicides were sprayed upon the foliage, however, the penetration into the xylem was much less effective, and it was only with dry soil and continued moistening of the tops that an appreciable downward movement of toxin could be obtained. Offord (8) tested the effectiveness of a number of herbicides on Ribes sp. and found that materials which reacted rapidly with the protoplasm resulted in a quick killing of exposed portions of the plant, but that the crowns and roots soon sprouted, apparently uninjured. The chlorates, on the other hand, were slow but much

No abstract

No abstract

There are certain demonstrable changes that take place within the gastrointestinal tract during the process of adaptation to external stimuli. The body as a whole reacts in this adjustment to a changing environment. We have presented our evidence and indicated some instances where these gastrointestinal changes can be considered significant from an epidemiological and preventive medicine standpoint.The loss of the self-disinfecting power, changes in acid-base equilibrium, and other demonstrable alterations within the lumen of the alimentary tract are only a part of the changes taking place in the organism during the process of adaptation to external environmental changes. If certain diseases are associated with a disturbance of the equilibrium between the parasites and the host, then it naturally follows that we must have more information upon the biological mechanism of the host in regard to its changes in susceptibility and resistance to the parasitic environment. Our present knowledge of bacteriology throws little light upon this epidemiological question. It has been the aim of the author to study the mechanism by which the organism adapts itself to certain environmental changes. We have avoided using pharmacological and other artificial agents that would produce body changes, but have restricted ourselves to simple alterations in diet, external temperature and similar mild or natural environmental factors, and followed the mechanism of adaptation to these physiological stimuli.The loss of the power of a body-covering layer, to destroy bacteria in contact with it, must increase the hazards of invasion of this body surface by bacteria. We have shown that a sudden change in the intra-intestinal acid-base equilibrium leads to an inhibition of the mucosa to destroy bacteria within its lumen and is accompanied at times by the appearance of viable bacteria in the thoracic duct lymph stream.If an organism does not adapt itself to its meteorological environment, it is more susceptible to its parasitic environment. The same is true of the nutritional environmental factors. Disturbances due to lack of adaptation to climatic changes can in part be offset by altering the diet. The weather and food factors cannot be separated and one can influence the other.Changes in climate are beneficial to the well-being of the population living in the temperate zones where meteorological conditions are ever changing as compared to the steady cold in the arctic or constant heat as in the tropics. Changes in food are also beneficial. A high protein meal is stimulating. In the tropics where the skin is in a state of over-stimulation due to the high external temperature and humidity the ingestion of an alcoholic beverage to stimulate the splanchnic system before a meal is beneficial. Acidifying an infant's food in hot weather is a common practice. Many such instances could be cited. It seems to be of advantage to an organism to be in a changing environment. The tonus of our physiological systems is not static or fixed, but is ever changing. The more delicate the index used to measure functional changes, the more frequently are such changes observed. These alterations in environment must not exceed the power of the organism to adapt itself to these changes.

No abstract

Nutrient fluxes in precipitation, throughfall, and stemflow were studied in an oak-hickory forest in southern Illinois for a three-year period beginning in 1973. Nutrient inputs in these water related pathways were approximately one-half those of litterfall: a major nutrient return mechanism. Considering these water carried nutrients (1 16 kg/ha/yr), 38% was contributed by precipitation, 35% by throughfall and approximately 27% by stemflow. Although the total nutrient input is only one-half that of litterfall, the net impact on short-term nutrient requirements is considerable because of their immediate availability. Nutrient inputs in litter represent a delayed return mechanism because of the relatively slow decomposition ( K E Y 'TERMS: precipitation; throughfall; stemflow; nitrogen; phosphorus; nutrients; nutrient cycles.) PTOCCSS.