SpirocJuzta. 43 



XII. SPIROCHiETA, Ehrenberg (Aihandl. Berlin. 

 Akad., 1833, p. 313). 



Cells united in long slender threads, which present a 

 considerable number of dose 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 zooglcea, but often felted in dense tufts. 



Distinguished from Spirillum by the long, closely wound, flexile 

 threads. 



61. S. plicatilis, Ehrenberg (l.c., p. 313). 



Spirillum plicatile, Dujardin. 



Spirulina plicatilis, Cohn. 

 Threads very short and slender, with numerous close 

 spirals, articulated, blunt at 

 the ends, 110-225 /a long 

 (according to Rabenhorst) ; 

 diameter of the single joints 

 (and thickness of the threads) 

 -2 -25 /*, according to Ehren- 

 berg. [Spores, according to Fig. 39.-^.fev..A<.^« >&<.^-& («, after 



Van Tieghem, 8 jU, in dia- a photograph hy Koch; b, 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. Set., 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 



