SPIROCHETE GROUP 441 



summarized as follows. According to several observers, multipli- 

 cation, frequently, though not invariably, takes place by longitu- 

 dinal rather than transverse division of the cell. Morphologic- 

 ally, it is believed that these organisms differ from the true bacteria 

 by being in all cases flexible, and swimming with a sinuous motion. 

 In several species, undulating membranes similar to those of the 

 protozoa have been demonstrated. Chromidia-like bodies, re- 

 sembling the scattered nuclei in some protozoa, have been identified. 



Sp. dentium, 



Sp. insequalis 



Sp. tenuis 



Sp. denticola 



Sp. undulata' ^H ^Sp. dentium 



Sp recta 



Fig. 194. Spirochaetae of different species. From a smear from a tonsillar 

 lacuna stained by Burril's India ink method (Gerber) . 



According to Prowazek, plasmolysis does not take place with salt 

 solutions several times as concentrated as those required for 

 plasmolysis of bacterial cells. Certain spirochetes have been 

 observed to enter red blood-cells, and there assume a coiled condi- 

 tion. A multiplication of the organisms has been observed in 

 the eggs of a tick which transmitted a spirochete disease, as have 

 also certain forms which have been interpreted as stages in a more 

 complex life-history. Leishman has found that certain spiro- 

 chetes, when ingested by the tick, lose their motility and change 



