The first report dealing with the effect of temperature on the nutritional requirements of microorgsms seems to be that of Mitchell and Houlahan (1946a). In the course of their genetic studies on Neurospora a mutant strain was isolated which required riboflavin for growth. They noted that this requirement was a function of the incubation temperature. When the mutant was grown at temperatures be...

ITCHELL and MITCHELL (1952) and MITCHELL, MITCHELL and TISSIERES M (1953) have shown that two strains of Neurospora crassa, poky and mi 3, of independent origin, differ from wild type and from each other in growth rate and cytochrome content. The differences are inherited maternally and thus appear to be associated with the cytoplasm. The object of this work has been to show what type of cytopl...