immune sera showed agglutination in dilu- tions too low to be considered positive. 9. Wolbachia sericea (Giroud and Mar- tin, 1946) Philip, 1956. {Rickettsia sericea Giroud and Martin, Bull. Soc. path, exot., 39, 1946, 264; Philip, Canad. Jour. Microbiol., 2, 1956, 267.) se.ri'ce.a. M.L. adj. sericeus silken. Minute, coccoid, diplococcoid and short rods up to 0.5 micron in length. Violet with Giemsa's stain and red with Macchiavello's stain. Bipolar staining may be observed. Cultivation: Not reported. Pathogenicity and source: Found both extracellularly and intracellularly in 19 of 241 mites examined {Sericothrombium holo- sericeum, a species which is not parasitic on vertebrates in any stage). No longer con- sidered pathogenic for the host mites. No susceptibility was found in laboratory animals. Genus VII. Symbiotes Philip, 1956. {Coivdnjia Macchiavello, Prim. Reunion Interamer. del Tifo, Mexico, 1947, 417; not Cowdria Moshkovskiy, Uspekhi Souremennoi Biol., 19, 1945, 18; Philip, Canad. Jour. Microbiol., 2, 1956, 267.) Although Cowdryia Macchiavello (1947) antedates Symbiotes Philip (1956), the former generic name is an orthographic variant of an earlier generic name, Cowdria Moshkovskiy (1945), and is therefore an illegitimate homonym. Sym.bi.o'tes. Gr. mas.n. symbiotes one who lives with a companion, a partner. Rickettsia-like, pleomorphic organisms living chiefly intracellularly in arthropod tissues and approaching most nearly the true symbiotic or commensalistic relationship to their hosts; this is evidenced by the development in the host of special organs, or mycetomes, though no species of the Rickettsiales is yet known to be confined to such a location. The type species is Symbiotes lectularius (Arkwright et al.) Philip. 1. Symbiotes lectularius (Arkwright et al., 1921) Philip, 1956. (Rickettsia lectularia Arkwright, Atkin and Bacot, Parasitology, 13, 1921, 35; Cowdryia lectularia Macchia- vello, Prim. Reunion Interamer. del Tifo, Mexico, 1947, 417; Symbiotes lectularia (sic) Philip, Canad. Jour. Microbiol., 2, 1956, 267.) lec.tu.la'ri.us. M.L. adj. lectularius the specific epithet of the common bedbug, Cimex lectularius. Minute, pleomorphic, intracellular or- ganisms, the typical form being coccoid or diplococcoid, 0.2 by 0.4 to 0.5 micron, staining deep purple with Giemsa's stain. Bacillary, lanceolate and thread forms, 0.25 to 0.3 by 3.0 to 8.0 microns, occur which stain more red than purple with Giemsa's stain. Granules were reported in the thread forms which were liberated during dark- field examination. Motility of some of the filamentous forms has been reported. The possibility that a true bacterium occurs in association has also been postulated. Cultivation : Attempts to grow this organ- ism on cell-free media have been unsuccess- ful. However, Steinhaus (Jour. Bact., ^2, 1941, 757) cultivated, from- suitable host sources, a diphtheroid in semi-solid media and embryonated chicken eggs; the relation- ship of the diphtheroid to this species was uncertain. Pathogenicity and source: Found espe- cially in paired, special organs, the myce- tomes, in the common bedbug {Cimex lectularius); also occurs in other tissues, the alimentary tract, ovaries, testes, Malpighian tubules and Berlese's organ. Transovarially transmitted between generations and so mutualistically adapted that it seems prob- able that every bedbug harbors the organ- ism. The same, or a related organism, was observed in the swallow bedbug {Cimex hirundinis) and in "accessory lobes" (mycetomes?) in the tropical bedbug {Cimex rotundatus). The only effect on the host was reported as swellings in the Malpighian tubules due to masses of organisms in the cells, though destruction of such cells was not noted. No effects were produced by in- jection into laboratory animals and into two human volunteers.
