THE GENUS SPIROCHETA AND ALLIES 



223 



he himself is not altogether certain of his ground in some cases. 

 Fantham was unable to confirm these observations, while Swellen- 

 grebel interprets these structures, probably correctly, as involution or 

 degeneration forms. All evidence of so-called conjugation described 

 by Perrin is unconvincing, and the sexual processes of these interesting 

 forms, as with all other spirochetes, remain undetermined. 



Wliile Spirocheta halhianii is the best known of the spirochetes, 

 it is quite evident, from the accounts of the various observers, that 

 much yet remains to be done before its life history is known. But we 

 know still less about the other forms of the group, especially those 

 which appear to be the causes of specific diseases. Nevertheless, 

 some problems connected with them have been solved, many careful 

 experiments have been planned and successfully executed, and many 



Fig. 89 



Types of flagellum insertion in bacteria. (After Btitschli.) 



structures and functions faithfully described. The literature is enor- 

 mous, and in the limited space of this chapter only the general trend of 

 observations and experiments can be given. 



B. The So-called Flagella of Spirochetes. — As stated on page 

 4.5, there is good reason to doubt the specific flagellum nature of the 

 attenuated ends of many of the spirochetes, and, owing to the extremely 

 small size of most of these organisms, it is hardly probable that the 

 question will be definitely settled one way or another very soon. Sev- 

 eral factors, however, combine to show that these organoids lack the 

 specific kinetic accompaniments characterizing flagellated protozoa. 

 In the latter, wherever carefully studied, and in plant and animal 

 flagellates alike, the flagella are deeply inserted in the protoplasm and 

 arise as outgrowths from the nucleus or from special basal bodies 

 (Fig. 100, p. 249). In spirillum the so-called flagella are of an entirely 



