CLADOTHBIX DICHOTOMA. 465 



Biologie, Band i, Heft i, p. 108, Breslau: Rossler, Arch, 

 f. Pharm., Bd. 233, 1895.) 



Here also should be included the interesting Leptothrix 

 ochracea Kiitzing, which does not belong to the lepto- 

 thrices in a strict sense, because of its fully developed mem- 

 brane. Winogradsky, who describes it in detail, gives the 

 following characteristics: slender, jointed, fixed threads of 

 bacilli, with membranes. The membrane is thick below, 

 thin at the free ends, and the terminal rods are entirely 

 without any membrane. The bacilli in the membrane are 

 motile, but this motility is lost as soon as the membrane 

 has reached a certain thickness. This variety thrives only 

 in water containing ferrous oxid. In the metabolic pro- 

 cess hydrated oxid of iron is deposited in the membrane. 

 In hay decoction prepared from well-water and freshly 

 precipitated hydroxid of iron the organism always grows 

 easily and rapidly. It forms yellowish flakes and films, 

 and in nature gives rise to extensive ocher deposits. (Com- 

 pare Winogradsky, Bot. Zeitung, 1888, p. 261.) 



Cladothrix dichotoma. Ferd. Cohn. 



(Cohn's Beitrage, Bd. I, Heft. Ill, p. 185.) 



Long, apparently non-segmented threads, with thick or 

 thin membranes, in part free, in part attached to putre- 

 fying algae. Thickness 1 to 5 a<. The pseudodichotomy 

 is especially interesting. It is dependent upon the growing 

 of a lower segment of a thread along by the side of a higher 

 one (Fig. 30). Pure cultures of this organism have been 

 but little studied; we have not possessed atiy. According to 

 Blisgen, the most recent investigator of this organism (Ber. 

 der deutsch. bot. Gesellschaft, 1894, p. 147), it grows 

 slowly and without perceptible liquefaction in gelatin con- 

 taining a little meat extract. 



The surface growth consists of a "round white patch," 

 which is not elevated, and from which, as from the stab, 

 after a few days delicate threads grow out. 



The threads have thin membranes when grown on gela- 

 tin and thick ones in dilute solutions of meat extract. The 

 membrane is patent at the end of the threads, and through 

 this opening, as also through irregularly occurring tears of 

 30 



