606 PATHOGENIC MICROORGANISMS 



cells among which they are seen, the microorganisms may vary from- 

 one-half to 9 or 10 times the diameter of a corpuscle. In fresh prepara- 

 tions of the blood, very active corkscrew-like motility and definite lateral 

 oscillation are observed. In stained preparations no definite cellular 

 structure can be made out, the cell body appearing homogeneous, except 

 in degenerated individuals, in which irregular granulation or beading 

 has been observed. Flagella have been described by various observers. 



FIG. 133. SPIROCH^ETE OF RELAPSING FEVER. Citrated normal rat blood. 

 (After Norris, Pappenheimer, and Flournoy.) 



Novy and Knapp 1 believe that the organisms possess only one terminal 

 flagellum. Zettnow, 2 on the other hand, claims to have demonstrated 

 .lateral flagella by special methods of staining. Norris, Pappenheimer, 

 and Flournoy, 3 in smears stained by polychrome methods, have described 

 long, filamentous tapering ends which they interpreted as bipolar, 

 terminal flagella, never observing more than one at each end. Spores 

 are not found. 



Cultivation. Innumerable attempts to induce these microorganisms 

 to multiply upon artificial media have been made. Novy and Knapp 

 succeeded in keeping the microorganisms alive and virulent in the 



1 Navy and Knapp, Jour, of Infec. Dis., 3, 1906. 



2 Zettnow, Deut. med. Woch., 32, 1906. 



3 Norris, Pappenheimer, and Flournoy, Jour, of Inf. Dis., 3, 1906. 



