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C C L~ POISONING I173 1 populations of 3 species of Hemophilus when diluted lo4-or 105-fold and incubated in the defined medium is comparable to the high degree found when exposed to DNA after incubation of a 1: 10 dilution in buffered saline, the function of the individual components of the medium requires further investigation. By analogy with the work of Fox and Hotchkiss(8) on the requirements for the '(creation" or "recreation" of competence in pneumococcal populations, the amino acids and bivalent cations of the medium may function in formation of DNA binding sites and in the DNA-fixation process. Albumin, essential for competence in the pneumococcus is not required by Hemophilus under the conditions investigated.Whether the components of the medium are required for synthesis of specific receptor sites, for a pinocytotic-like means of incorporation of the DNA molecule, or for active transport of DNA across the cell membrane cannot now be answered. However, demonstration of the emergence or expression of competence in the medium provides a tool for further study of both the emergence and decay of the competent state under chemically defined conditions. Summary. Three species of Hemophilus, grown under the method of Goodgal and Herriott, were shown to emerge to a state of competence for transformation to SM-resistance in a chemically defined medium: L-aspartic, L-glutamic acids in buffered saline containing calcium and magnesium ions. The degree of competence of a "standard" culture was enhanced many-fold in 30 .to 60 minutes even when diluted 105-fold in the defined medium. The emergence of competence in the synthetic environment was temperature dependent and inhibited by chloramphenicol ; multiplication was not necessary. Competent populations washed in the defined medium retain competence ; in populations which have lost transformability as a result of washing in buffered saline, competence may be restored. Data presented suggest that the competence which emerges reflects the final attainment of the competent state rather than its "restoration" in cells which were competent at an earlier period during growth of the population.

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