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Radiocarbon uptake by Thalassiosira pseudonana was used to compare the effect of bottle type on primary productivity. Three types used in primary productivity studies were considered: standard soda-lime bottles, commercial Pyrex bottles, and quartz bottles. Transmittance within the ultraviolet region (e.g. 290–320 nm) varied significantly (quartz > Pyrex > Wheaton “800” glass). Measurements of radiocarbon uptake in the three bottle types under white fluorescent lamps alone (4.48 W·m−2 [380–700 nml) were not significantly different. However, when combined with the sunlamp/filter system (0.74 W m−2 [290–320 nm]), there was a significant difference in productivity. The environmentally significant ultraviolet portion of the solar spectrum should be considered when culture bottles are selected for in situ primary productivity studies.

Effects of ultraviolet radiation on the development of metabolism of estuarine bacterial populations in laboratory microecosystems were studied. When compared with bacterial populations developing under an ultraviolet-deficient condition, the heterotrophic populations from microecosystems exposed to an ultraviolet-supplemented sprectrum displayed an overall decrease in total numbers, an increase in the proportion of pigmented cells, a decrease in the number of cellulolytic microorganisms and an increase in heterotrophic respiration. Ultraviolet radiation in the 290–320 nm waveband was the apparent stressful environmental parameter.

An increase in the transmission of solar radiation in the UV-B region (specifically, 290–320 nm) is expected to occur as a result of anthropogenic degradation of stratospheric ozone. The potential impact of increased levels of UV-B radiation upon the biosphere is of ecological concern. In a previous study a community of estuarine organisms received a daily exposure to a simulated solar spectrum enhanced in UV-B radiation for a period of six weeks. A dominant species of diatom growing at the surface of these communities was isolated and identified to beMelosira nummuloides. Short chains of this diatom were irradiated for a four-hour period on each of three consecutive days. Fluorescent sunlamps filtered by a 290 nm cut-off filter (0.13–0.50 mm cellulose acetate) or a 315 nm cut-off filter (0.13mm Mylar ‘S’) provided a range of fluence which closely approximated natural fluence levels. A least squares regression analysis of the number of cell divisions on the biologically weighted fluence indicated a significant depression in the growth of this species by radiation in the 290–320 nm waveband.

far as I'll go," etc. Construction must serve clarity and precision. We should not say "I won't come until October," but "I won't come before October"; not "he walks in the house," but "he walks into the house," etc. Just so, the habits of pronunciation and articulation offer the finest medium for careful mental-nervous habituation. Character-formation comes only through inhibition of ingrained tendencies, of suggestions to easy rather than accurate habits, etc. In speaking, the challenge to inhibit, to reject poor models and slovenly states of mind, is constant and always present. The great value of acquiring good language-habits is, therefore, patent to all who have insight into these matters.