Page:Bergey's manual of determinative bacteriology.djvu/302

 The cells are attached to long, slender stalks which radiate from a common center; as many as 8 stalks may be attached to a com- mon holdfast; usually thej' are attached directly to a glass slide, occasionally to algae or other organisms or to some amor- phous debris. Multiplication is by budding, the buds being globular in shape. The smaller cells stain solidly, but the larger cells that are budding show a differentiation of the protoplasm: the free end stains deeply while that part of the cell which is attached to the stalk stains more faintly. Young cells are Gram-positive, but budding individuals are Gram-negative. Temperature relations: Found only in lake water where temperatures do not ex- ceed 23° C. Comments: It is believed that the char- acteristic growth of this organism in whorls may be best explained by assuming that when the buds germinate they first undergo a simple fission, perhaps producing clusters of cells, and that then, from these clusters, the individual cells secrete stalks which thus radiate from a common holdfast. Related species: Similar stalked bacteria which reproduce by budding are illustrated by Henrici and Johnson (ibid., 77 and 91) but are not named or described in detail. Source: From glass slides submerged in Lake Alexander, Minnesota. Habitat: Presumably widely distributed in fresh-water ponds. Does not occur closer to the shore than the 2-meter contour. Found constantly in the open lake at all depths up to 13 meters. Occurs more abun- dantly in the fall months than in the sum-