456 THE SPIROCHETES 



When motility is reduced, the organism may rotate along its axis in one and then another 

 direction without changing its curves. The cell body consists of a spiral, elastic axial fila- 

 ment, a layer of protoplasm of varying thickness around the lilament, and a delicate flexible 

 membrane covering the whole body. Both ends are sharply drawn to a point. There may 

 be a terminal filament (Figs. 22-29, 43~47) at one or both ends {T. pallidum, T. recurrentis) , 

 or peritrichal flagella (Fig. 53) may be present {T. anserinum). The polar terminal projec- 

 tion may be a smooth or a finely curved elastic spiral appendage of immeasurable thinness, 

 of a length of one-fourth to one-third of the body. The terminal projections are more com- 

 mon in cultures and exhibit a swinging movement around the extremity of the organism. 

 The thickness of the protoplasmic coat varies in different species, is thin in Treponema 

 pallidum, T. perienue, and T. cuniculi; somewhat thicker in T. rejringcns; and still thicker 

 in T. recurrentis. In the organisms with the more plasmatic substance there is often a mask- 

 ing of the elementary curves of the axial filament during active movement. The tendency 

 of the organism to take up stains is proportional to the thickness of the protoplasmic coat — 

 the more protoplasm the greater the tendency to take up the violet nuance of the Giemsa 

 stain. Transverse division. Pathogenic types transmitted by contact {T. pallidum, T. per- 

 ienue, T. cuniculi) or by insects {T. recurrentis, T. duttoni, T. anserinum) . The tissue-residing 

 forms require anaerobic conditions for growth; the blood-inhabiting species are aerobic. 

 Filterable under certain conditions. Granular phase observed. 



Genus Cristispira {Gross, igii). — Highly active, cylindrical, wavy cell body. There is 

 present a more or less wavy membranous structure composed of numerous fine elastic wavy 

 fibrils resembling bacterial flagella, running spirally along the entire body hke a veil (Figs. 

 19-21); in a cross-section it is seen to form a ridge, hence the name Cristispira. In stained 

 specimens the protoplasm appears cross-barred or chambered (Figs. 40-42), with alternating 

 deep-staining transverse septa (volutin and chromidial granules) and pale-stained spaces 

 between septa. There is a distinct cell membrane which is elastic, as shown by the marked 

 flexibihty of the living organism in its active movements. No terminal flagella or axial fila- 

 ment present. Gross's view as to the multicellular nature of the organism and the occurrence 

 of sporulation has not been confirmed. No definite chambered structure can be demonstrated 

 in the fresh state. Habitat: Crystalline styles of various LamelUbranchs. 



Genus Saprospira {Gross, igii). — Differs from Cristispira in the absence of a crista. The 

 multicellular structure of the organism and the occurrence of sporulation, as described for 

 this genus, await confirmation. Habitat: Foraminiferous sand; saprophytic; a group very 

 httle known. 



Genus Leptospira {Noguchi, 1917). — A long, slender, cylindrical, highly flexible filament, 

 with tightly set, regular, shallow spirals. Both extremities gradually taper to sharply drawn 

 points. In some forms the curves are so closely set that the distance between two spirals is 

 too small to measure; in saprophytic forms there is an appreciable distance between adjacent 

 spirals. A smooth axial filament with hooked ends may be present (Fig. 33) but is not 

 demonstrable by staining. Terminal filaments are sometimes observed (Figs. 30-34, 57-76). 

 The terminal portions of both extremities of the organism are endowed with marked motility 

 in contrast to the middle portion of the body, and they may be bent to a hook or stretched 

 out; the hooked-end portions are characteristic of the species. Perhaps there is a membrane. 

 Transverse division: Transmission by insects or rodents in the case of pathogenic varieties, 

 which invade both tissues and blood. Some species are saprophytic. All are obligator> 

 aerobes. Filterable. Granular phase observed. 



Table I is a resume of the characteristics upon which generic differentiation is 

 made 



