CHAPTER 38 



THE SPIROCH.ETES 



The name Spirochsete was first given by Ehrenberg in 1833 to a large flexible motile 

 organism occurring in water ; it is now used as a general term for all elongated, 

 motile, flexible organisms that are twisted spirally around their long axis. Though 

 the spirochaetes vary greatly in size, they all possess certain features in common : 

 thus they possess no flagella ; they exhibit no antero-posterior polarity {i.e. they 

 can move either forwards or backwards) ; they contain no colouring matter and 

 no cyanophycin granules ; they show no definite localized nucleus : they divide 

 transversely, division being either simple or multiple ; and they exhibit no sexual 

 phenomena of reproduction. These properties bring them closely into line with 

 the Bacteria, to which they are more nearly related than to the Protozoa. Indeed, 

 as Dobell (1912) points out, while there are 

 many features in which they differ from the 

 Protozoa, there is only one feature that 

 differentiates them from the bacteria, namely 

 motility without flagella. Even this differ- 

 ence is now subject to doubt, since studies 

 by the electron microscope on some of the 

 treponemata have revealed filamentous 

 bodies that may be interpreted as flagella 

 (Mudd, Polevitzky and Anderson 1943, Wile 

 and Kearney 1943). 



Without entering into the disputed ques- 

 tion of their classification, it is convenient 

 for descriptive purposes to divide the 

 spirochaetes into four groups — Spirochceta, 

 Cristispira, Treponema, and Leptospira. 



Spirochaeta.^ — The members of this group possess an axial fibre, around which 

 the body is twisted in a spiral manner, in just the same way as a spiral staircase is 

 built round the newel. The organism possesses a series of regular primary spirals ; 

 during motion a series of secondary waves may be superimposed on these, but 

 whatever form the organism as a whole may assume, the primary spirals remain 

 intact. Metachromatic granules of volutin are distributed uniformly throughout 

 the length of the organism. The type species, Spirochceta plicatilis Ehrenberg, is 

 usually 200-500 // in length and 0-5-0-7 [x in thickness (Wenyon 1926). The 

 number of primary spirals is 100 to 250, the distance between successive turns 

 being about 2 [i. So far no members of this group have been found to be capable 

 of causing disease. 



907 



Fig. 



d 



THE SpIKO- 



214. — Diagram of 



CHUTES. 



a. Spirochceta. b. Cristispira. 



c. Treponema. d. Leptospira. 



(After Noguchi.) 



