Hydrogen sulfide not produced. Salt concentration range: 1.5 to 5.0 per cent. Strictly aerobic. Optimum temperature, Isetween 22° and 25° C. Source: Lsolated from sea water. Habitat: Sea-water. Probably on decay- ing marine vegetation. 10. Cytophaga diffluens Stanier, 1940. (Jour. Bact., 40, 1940, 623; Jour. Bact., ^2, 1941, 546.) dif'flu.ens. L. part. adj. diffluens flowing away. Pointed, sometimes spindle-shaped, flex- ible rods, 0.5 to 1.5 by 4 to 10 microns. In old cultures involution forms consisting of long, twisted, thin threads are found. Star- shaped aggregates of cells occur in liquid media. Creeping motility on solid surfaces, non-motile in liquids. Growth on a sea-water-peptone agar plate begins as a thin, pink, rapidly spreading swarm which often covers the entire surface in a few days. The swarm gradually in- creases in thickness and develops an irregu- lar, beaten-copper surface due to the lique- faction of the underlying agar. After 4 to 5 days the color becomes orange. Liquefaction of the agar is ultimately almost complete. Sea-water-gelatin stab: Rapid liquefac- tion. Growth in liquid media is turbid, often with suspended floccules and a heavy pel- licle. Xylose, glucose, galactose, lactose, malt- ose, cellobiose, cellulose, agar and alginic acid are utilized, but not arabinose, sucrose, chitin or starch. Yeast extract and peptone are the only suitable nitrogen sources known. Weakly catalase-positive. Indole not produced. Nitrites produced from nitrates. Hydrogen sulfide not produced. Salt concentration range: 1.5 to 5.0 per cent. Strictly aerobic. Optimum temperature, between 22° and 25° C. Source: Isolated from sea water. Habitat: Sea water. Probably on decaying marine vegetation. 11. Cytophaga sensitiva Humm, 1946. (Duke Univ. Marine Lab., North Carolina, Bull. 3, 1946, 64.) sen.si.ti'va. L. noun sensus perception; M.L. adj. sensitivus sensitive. Cells long, slender, flexuous rods, 0.8 to 1.0 by 7.0 to 20 microns. Cell ends not ta- pered or only slightly so. Gram-negative. Cells exhibit creeping motility on agar with ability to reverse direction of movement without turning. Bending movements occur in liquid media. Colonies light orange, thin and shining. Irregular margin. Outer part composed of a single layer of cells, spreading rapidly, the center somewhat thicker and more or less opaque, sunken in the agar. Agar liquefied. Single colony may nearly cover the surface of the agar in the Petri dish within one week; center of colony sinks to the bottom of the dish and may develop vertical sides. Usu- ally the colony begins to die after a week or ten days from the center outward, as shown by loss of pigment. Apparently no water- soluble pigment is produced. Colony 18 mm in diameter and gelase field 25 mm in diame- ter after three days on agar containing 0.8 per cent potassium nitrate and 0.8 per cent peptone (iodine stain). Gelatin: No growth. Milk: No growth. Nitrite apparently not produced from nitrate (agar medium). Optimum nitrate concentration of me- dium appeared to be 0.5 per cent. Fair growth on sea water plus agar only, and on agar containing 1.0 per cent potassium ni- trate. Slight growth on 2.0 per cent nitrate agar. Optimum peptone concentration ap- peared to be about 0.1 per cent; growth in- hibited by concentrations of peptone ex- ceeding 0.4 per cent. No growth on agar media containing any one of the following substances in a con- centration of 0.2 per cent: glucose, starch, ammonium sulfate. The basal medium, however, supported excellent growth. Repeated efforts were made to obtain a pure culture by streaking plates and by pouring plates. These were finally successful by the use of an agar medium that con- tained 0.1 per cent peptone, 0.05 per cent beef extract, 0.05 per cent glucose and traces
