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YOUNG cultures of B. fluorescens liquefaciens quantitatively secrete a proteinase into the culture medium, as was found by Virtanen & Tarnanen [1931; 1932] and Virtanen & Suolahti [1937]. In previous work on the proteinase of Cl. histolyticum Weil & Kocholaty [1937] reached a similar conclusion. Recently Maschmann [1938, 1] reported on a bacterial proteinase (B. botulinus, B. Welchii) which he considers to be in the "intracellularly acting proteinase of anaerobic bacteria", differing from the proteinase which is secreted by the bacterial oell. In a later publication on Cl. histolyticum, the same author [Maschmann, 1938, 2] concludes that this microorganism produces three distinct proteinases. These are somewhat vaguely differentiated according to their actions on different protein substrates and their behaviour towards cysteine and other activators. Two of these enzymes are believed to be " extracellular " in character, being secreted in the early stages of bacterialgrowth and to be indifferent towards, or even inhibited by, cysteine and other common activators. The third enzyme is considered to be "intercellular", and to differ from the others in its ability to hydrolyse clupein but not gelatin, and to be activated by-SH compounds. Maschmann claims that the activation phenomena observed by us on culture filtrates of Cl. histolyticum are due to this intracellular proteinase, which is freed only by autolysis of the bacterial cell. Our previous work on this microorganism has been extended and the results are still at variance with the conclusions reached by Maschmann. In cultures of Cl. histolyticum, both the bacterial growth and the proteolytic activity (initial and full') of the cell-free bacterial filtrates, reach a maximum value within

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I This project has been supported by the Thos. H. Dougherty, Jr., Fund, and by grants from Smith, Kline and French Laboratories and the Department of Agriculture, Commonwealth of Pennsylvania.

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