280 



ORDER III. HYPHOMICROBIALES 



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- 



