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GENERAL INTRODUCTIONIn purely physical or mechanical systems, a stress or force induces a strain. Similarly, from a physiological standpoint, an environmental stress induces a strain on an organism that must be compensated for or tolerated. Each of the five chapters in this thesis addresses the effect of an environmental stress on touch-evoked rapid escape reflexes in aquatic oligochaetes-Chapter one will assess the lethal limits of dissolved cadmium and will relate these limits to sublethal pre-treatment with cadmium.Chapter two will assess the effect of acute and prolonged exposure to anoxia on escape reflex function. Chapter three will assess the lethal limits and sublethal effects of pH and amiaonia/ammonium exposure. Chapter four will assess the effect of temperature, both acute and prolonged exposure, on 3 escape reflex function. Chapter five will assess the effect of repeated tactile stimulation on escape behavior and, although it represents a sensory cue more than a stress, it is included because repeated tactile stimulation routinely occurs within the worm's environment. These particular stresses were chosen because of their relevance to the freshwater environment and worm's survival within that environment.The specific effects (strains) to be examined are the changes in the physiological performance of selected components of the escape reflex including: touch sensitivity, giant fiber conduction velocity, and giant fiber-mediated muscle electrical potentials. Touch sensitivity is a measure of...