132 MICRO-ORGANISMS AND DISEASE. [CHAP. 



called by Cohn l spirocJiceta pl/catilis. The spirillum found 

 in the tartar of the teeth is of this form, spirochceta denticola. 

 But there exist all intermediate forms between a single 

 spirillum tenue and a spirochfeta. In stained specimens the 

 construction of the spirochseta from several spirilla tenua is 

 very distinct. 



(b] Spirillum undula is much thicker and shorter than the 

 former ; there are all forms between such as are only half a 



FIG. 95. SPIRILLUM UNDULA FIG. 96. SPIRILLUM VOLUTANS 



(AFIER COHN). (AFTER COHN). 



turn to such as are of a whole turn of a spiral. It is motile 

 and forms chains of two or more elements, occurring also 

 in continuous masses, occasionally held together by a hyaline 

 interstitial substance. 



(c) Spirillum volutans. These organisms are giant spirilla : 

 long and thick, with granular protoplasm ; 0'025 to 0'03 mm 

 long ; motile, and with a flagellum at each end. 



1 Beitrtiye zur Biologic d. Pflanzen, vol. ii. 



