THE BEHAVIOR OF OSCILLATORIA TEREBRIFORMIS IN HOT SPRINGS(1).

Oscillatoria terebriformis, occurring from 54 to about 35 C in eastern Oregon hot springs, forms dense reddish-brown surface mats which are held together by the interwoven nature of the trichomes and not by a gel-like matrix, thus retaining the flexibility inherent in free trichome motility. The trichomes demonstrate gliding, flexional, and contractile movements. When the trichomes are interconnected, the mat contracts or retracts essentially as a unit in response to high light intensity (ca. 100 cm/hr) or supraoptimal temperature (ca. 2 cm/hr). Under lower light intensity and optimal temperature, the mat expands by the gliding movements of individual trichomes (1-3 cm/hr). Probable positive and negative phototopotactic responses of trichomes to low and high light intensities, respectively, also influence the density of the surface mat. Thus, the population of Oscillatoria is able to adjust its position and density rapidly by migrations and contractions, remaining almost always within the full optimal temperature range and fairly well xuithin the optimal light conditions as well.