480 Bulletin 167 



Morphological Characters 

 dimensions 

 Stained specimens for measurement were prepared from 

 young- (24 hour) agar and broth cultures with watery solutions 

 of the common anilin stains, with anilin water gentian violet, and 

 with carbol fuchsin. Measurements using a Zeiss homogenous 

 1 -12 objective and a number 3 micrometer ocular, or by photog- 

 raphy, showed a diameter of from .9 micron to 1 micron, the 

 majority being slightly less than 1 micron. The length varied 

 from 1.5 microns to 3 microns. Living organisms upon agar 

 hanging blocks mea c ured by either method were found to have 

 the same dimensions as the stained organisms with the possible 

 exception of a few instances, in which there was an apparent 

 length of 5 to 6 microns. Since careful focusing in some of these 

 cases revealed indistinct lines of fission it is possible that the 

 longer bodies are really filaments of 2 or more segments. (See 

 I 'late Y11I, figs. 9 and 10). 



CULTURES ON AGAR HANGING BLOCKS 



Agar hanging block cultures were prepared from small blocks 

 of nutrient agar cut from poured plates and placed on sterile 

 cover glasses, the surface next to the cover glasses being first 

 touched with a dilution from a young nutrient broth culture. The 

 cover glasses were placed on hollow ground slides and sealed 

 cither with vaseline or with a bit of melted agar to prevent evapo- 

 ration, and the preparation held at room temperature (20-24 C.) 

 for observation under the microscope. In abundant moisture the 

 grouping was similar to that described on page 470 under the 

 heading "Form." In cultures too dry to afford easy locomotion, 

 but not dry enough altogether to inhibit motion, long, variously 

 oriented, vibrating or squirming chains were observed. (See 

 Plate VIII, figure 8, in which the motion of the chains gave the 

 negative a badly blurred appearance). Blocks in which motility 

 was prevented by lack of moisture developed chains of from 2 t<> 

 many segments, the elements usually showing parallel orienta 

 tion bnl sometimes developing an irregular grouping. 



