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THE AMERICAN NATURALIST [Vol. XLII 



most distinctly observed and delineated. Finally 

 Prowazek calls attention to various protoplasmic accumu- 

 lations or globules which make their appearance at cer- 

 tain times and in his opinion are not mere products of 

 regeneration, but represent special resting stages in which 

 protoplasm and chromatin granules experience involu- 

 tion. These peculiar processes have also been observed 

 by other investigators on other species and may possibly 

 be interpreted as particularly related to the sexual cycle. 



Prowazek concludes that as regards the systematic 

 position of the chicken spirochete {8. gallinarum), one is 

 compelled on the basis of the structure, relation to re- 

 agents, manner of plasmolysis, and also on the basis of 

 temporary cell parasitism to place the species among the 

 protozoa and in close proximity to the trypanosomes. 

 The undulating membrane was observed by Schaudinn in 

 8. dentium, refringens and ziemanni. The existence of 

 this structure can no longer be questioned. The large 

 form discovered by Keysselitz suggests the large 8. 

 plicatilis and forms the transition to 8. balbianii of the 

 oyster which is without doubt closely related to the 

 trypanosomes. 



In a very recent paper Fantliam (1908) demonstrates 

 the occurrence and character of the spiral membrane in 

 8. balbianii and 8. anodontce. He also explains the 

 character of the movement as due to myonemes in the 

 spiral membrane. Longitudinal division he finds to be 

 frequent and to involve first the basal granules, then the 

 membrane, next the chromatin masses and finally the 

 body, the halves of which subsequently remain attached 

 end to end. Fantham sees no clear evidence of sexual 

 dimorphism, and finds the spirochetes non-plasmolvzable 

 and without aerobic reactions. As characters manifest- 

 ing bacterial affinities he lists the diffuse nucleus like 

 spirilla; transverse fission even though infrequent, and 



