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Lysine was fermented by Fusobacterium nucleatum ATCC 25586 with the formation of about 1 mol each of acetate and butyrate. By the use of [1-14C]lysine or [6-14C]lysine, acetate and butyrate were shown to be derived from both ends of lysine, with acetate being formed preferentially from carbon atoms 1 and 2 and butyrate being formed preferentially from carbon atoms 3 to 6. This indicates that the lysine carbon chain is cleaved between both carbon atoms 2 and 3 and carbon atoms 4 and 5, with the former predominating [1-14C]acetate was also extensively incorporated into butyrate, preferentially into carbon atoms 3 and 4. Cell-free extracts of F. nucleatum were shown to catalyze the reactions of the 3-keto,5-aminohexanoate pathway of lysine degradation, previously described in lysine-fermenting clostridia. The 3-keto,5-aminohexanoate cleavage enzyme was partially purified and shown to have properties much like those of the clostridial enzyme. We conclude that both the pathway and the enzymes of lysine degradation are similar in F. nucleatum and lysine-fermenting clostridia.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The American Society of Parasitologists is collaborating with JSTOR to digitize, preserve and extend access to The Journal of Parasitology. INTRODUCTIONIn connection with a study of the life history and morphology of Spiroxys contortus (Rud.) during the years I929-I932 inclusive I had the opportunity to compare my material collected from the stomachs of various species of North American turtles with specimens of S. contortus from Europe. At the same time all other members of the genus available to me were examined and redescribed, the taxonomy of the genus and its member species was revised and appropriate diagnoses were prepared. HISTORICAL ACCOUNTRudolphi (I819: 242-243) was the first to describe a nematode belonging to the present genus Spiroxys under the name Spiroptera contorta from the stomach of Emys orbicularis (Linnaeus) (Testudinis orbicularis). He intimated that Spiroptera contorta might be synonymous with Ascaris testudinis, but stated (I809: I98-199) that he was unable to obtain the appendix by Braun to Schneider's "Naturgeschichte der Schildkr6te" (1789) in which a description supporting this name was supposed to appear. Baylis and Lane (I920) also failed to find the reference and designated Ascaris testudinis as a nomen nudum. Schneider (I866: 1I25-I26) established the genus Spiroxys to include only one species, contorta R. which he separated from the genus Spiroptera R. He failed to change the ending of contorta to contortus to make it agree in gender with Spiroxys with a masculine termination. Indeed, most of the subsequent authors of specific names for mem-* Contribution from the Zoological Laboratory and the Biological Station of the University of Michigan. I wish to express my sincere appreciation to Dr. George R. LaRue,

Acanthamoeba castellani and Torulopsis famata cells were cultured together for 10 days at three different temperatures: 18, 25, and 32 C. In