| Popis: |
SummaryRe-examination of growth-factors for vegetative spores of Oedogonium cardiacum, including the kind and strength of soil extract in the culture-medium, light-intensity, temperature, and gas-bubbling during the controlled growing period, has led to standardized growing conditions and reproducible results. By recording the position of spores on special gridded slides, the subsequent history of each initially-selected spore can be determined precisely. Measurements of the radio-sensitivity of these young spores, determined by calculating the percentage of chains with more than eight cells after five days growth, gave consistent results. The 60Co radiation dose required to produce the 50 per cent effect varied in different experiments between 3000 and 3400 rads. Radiosensitivity of these spores does not depend either on their average age or on their sex.Preliminary experiments with a completely inorganic medium in place of the soil extract have yielded promising results, and further investigations are i... |
