908 THE SPIROCHETES 



Cristispira. — The peculiar characteristic of members of this group is the possession 

 of a band-like membrane or crista, which runs in a spiral manner along the organism. 

 This membrane is extremely thin ; its width is much the same as that of the 

 organism itself, except at the ends, where it narrows down to fuse with the surface 

 pellicle. The body of the organism is divided into chambers by septa of thickened 

 cytoplasm, and on either side of each septum, or sometimes distributed irregularly 

 through the more fluid cytoplasm in the chambers, are a number of metachromatic 

 granules. The type species, Cristispira balbianii, is found in the crystalline style 

 of the oyster ; it is about 45-100 /n long and 1-1-5 ju broad (Wenyon 1926). Other 

 species have been found in a similar situation in other Mollusca. 



Treponema.— Members of this group possess neither an axial fibre nor a crista. 

 According to some observers the body is divided up into chambers like that of a 

 Cristispira, but this is by no means certain. The presence of metachromatic 

 granules is doubtful. The organism shows a number of primary spirals, which 

 may be closely or loosely wound ; during movement secondary turns may develop 

 but at rest these disappear so that the organism is straight. The ends may be 

 rounded or pointed, and in some members it is possible to distinguish a thin drawn- 

 out filament at the ends ; this is probably not a true flagellum, but the remains 

 of the thin connecting bridge of cytoplasm that is seen during transverse division. 

 Electron micrographs (Wile et al. 1942, Wile and Kearney 1943, Mudd, Polevitzky 

 and Anderson 1943) show the presence of a delicate cell wall, or periplast, enclosing 

 the inner protoplasm. Dense granules, 40-90 mju in diameter, are often seen in 

 the protoplasm ; and large, irregular, spheroidal bodies, 150-500 m^ in diameter, 

 may occur attached to the cell near the end, or connected with it by a short stalk. 

 What have been interpreted as true flagella may be seen, often in groups of four, 

 along the sides or near the ends, of Trep. pallidum and Trep. macrodentium. 

 Treponemata are widely distributed ; numerous species have been described in 

 water, in the gut of certain insects such as white ants and cockroaches, and in the 

 large gut of the toad ; in human beings they are found in the mouth, sometimes 

 in the alimentary tract and the bronchi, around the urethral orifice, in certain 

 ulcerating conditions of the skin, in condylomata, in the blood of patients with 

 relapsing fever, and in the manifold lesions of syphilis. They vary considerably 

 in size ; thus Treponema termitidis Leidy is 20-60 fi long and 0-5 fj, broad ; on 

 the other hand, Treponema parvum may be only 3// in length and 0-2 fj, in thickness 

 (DobeU 1912). 



Leptospira. — The members of this group possess neither axial filament nor 

 crista ; their cytoplasm is not obviously chambered. They show, however, a large 

 number of closely wound, primary spirals ; this differentiates them from the 

 treponemata, the spirals of which are fewer and less closely wound. Moreover, 

 the leptospirse frequently have their ends turned round at a sharp angle to the rest 

 of the body. When the organism is at rest the ends appear characteristically 

 hooked ; but when it is in motion, rotating round its long axis, the ends take on 

 the appearance of button-holes, the narrow pointed end of the button-hole being 

 attached to the body of the organism, the wider and rounded end being free. During 

 motion secondary curves often appear and disappear in rapid succession, giving 

 the organism a resemblance to a C, 0, S, or other curved letter. The primary 

 spirals are absolutely regular, and remain intact throughout all the various con- 

 tortions executed by the organism as a whole. Tlie leptospirse are widely dis- 

 tributed in water, and can be easily demonstrated in it by simple cultural methods 



