Spirochceta. 43 



XII. SPIROCH^TA, Ehrenberg (Abhandl. Berlin. 

 Akad., 1833, p. 313). 



Cells united in long slender threads, which present a 

 considerable number of close spiral turns. The threads are 

 very actively motile ; in fact they swim forwards or back- 

 wards, rotating round their longitudinal axes, and can more- 

 over bend themselves in the most varied manner. Not 

 forming a zoogloea, but often felted in dense tufts. 



Distinguished from Spirillum by the long, closely wound, flexile 

 threads. 



6 1. S. plicatilis, Ehrenberg (I.e., p. 313). 



Spirillum plicatile, Dujardin. 



Spirulina plicatilis, Cohn. 



Threads very short and slender, with numerous close 

 spirals, articulated, blunt at 

 the ends, 110-225 !" l n g 

 (according to Rabenhorst) ; 

 diameter of the single joints .^ rsQrs 

 (and thickness of the threads) 

 2-25 /A, according to Ehren- 

 berg. [Spores, according to Fig ^_ spirMa plicatilis (a> ^ 



Van Tieghem, 8 p. in dia- a photograph by Koch; 6, after 



meter.] (Fig. 39,) 



In bog-water, among Algae. 



This species is said by Koch to be distinguished from the others 

 especially by the doubly undulated contour of its filaments. But still 

 filaments with a simple spiral are very abundant. [Dr. Klein (Quart. 

 Jour. Micr. Sci., xv. 382) asserts that he has seen all intermediate 

 forms between this and Spirillum tenue, with which he unites it. TR.] 



62. S. Obermeieri, Cohn ("Beitrage," i. p. 196). 

 Morphologically almost the same as S. plicatilis, perhaps 



