BACTERIUM ZOPFII. 293 



Bacterium Zopfii. Kurth. (Botan. Zeit., 1883.) 



(Plates 29 and 30.) 



Microscopic Appearance. — There occur all forms 

 from long threads to short rods. Often the threads break 

 up into nearly spherical members (30, ii). 



Motility. — Very active, dependent upon numerous 

 peritrichous fiagella (30, ix). 



Staining Properties. — Stains well by Gram's method. 



Requirements as to Nutrient Media, Temperature, 

 and Oxygen. — Facultative anaerobe, satisfied with the 

 greatest variety of nutrient materials; grows at room and 

 incubator temperatures. 



Gelatin Plate. — (a) Natural size: Delicate, whitish- 

 gray colonies, resembUng spider' s web or mold n:iycelium 

 (29, vi). Later there appear little branches upon the 

 threads, which are more distinct the more superficially 

 they are located. The colonies (29, v) then resemble 

 those of the Bacillus mycoides (37, vi, ix). 



(6) Magnified 50 to 100 times : Very characteristic. The 

 original colony serves as a central part, from which radiat- 

 ing threads pass outward on all sides, which are more or 

 less branched and matted together. Between these lie 

 zooglese of the most variable forms: resembling loops of 

 hair, corkscrews, whipcords, and sausage with marked re- 

 flection (29, vm). When magnified 90 times, the indi- 

 vidual threads appear as wavy strings with wide lumina, 

 arranged in a most irregular manner (29, vii). The 

 ribbon-like zoogleic forms, when magnified 90 times, 

 appear composed of highly refractive, often granular 

 threads (30, i). The elongated, sausage-like forms appear 

 decidedly irregular. They consist of oval, overlapping, 

 yellowish-gray, homogeneously shaded clumps. At the 

 end of such a chain there are usually bough-like branch- 

 ings. Between these lie younger zooglese, bounded by two 

 notched lines (30, vii). 



Gelatin Stab. — The stab is provided with very delicate, 

 fine, parallel outgrowths, which are longest near the sur- 

 face and become shorter as they become deeper in the 

 tube. Surface growth is delicate, transparent, gray, 



