i 5 8 SCIENCE PROGRESS 



S. muris (Wenyon) or S. laverani (Breinl and Kinghorn) is 

 found in the blood of mice. It is a very small form. 



S. refringens (Schaudinn) is associated with Treponema 

 pallidum in syphilitic lesions. 5. refringens is the more refractive 

 in life, and has a smaller number of undulations than T. pallidum, 

 while it stains more readily (fig. i, b, c). 



The accounts of the structure of many of these Spirochaetes 

 are incomplete. Most of them are very small in size, and their 

 chromatin structure and details regarding a membrane usually 

 need re-investigation. 



5. culicis (Jaffe) has been described recently from the 

 alimentary tract of the larva of a mosquito, Culex pipiens. Still 

 more recently a species, S. bufonis (Dobell), has been notified 

 from the rectum of a toad. 



Spirochceta gigantea (Warming, 1875, from the coasts of Den- 

 mark), found in brackish water, is stated by Swellengrebel (12) 

 to be a Spirillum, and recently has been described very 

 carefully by him as Spirillum giganteum. It divides by trans- 

 verse fission. 



It will thus be seen that three main distributions are known 

 for Spirochaetes — namely, the blood stream, the various fluids 

 of the alimentary tract, and water {e.g. pond-water for 

 S. plicatilis). These media probably represent in inverse order 

 the evolutionary line of habitat of these organisms. 



The study of Spirochaetes has attracted much attention 

 during the last few years, since Schaudinn published his re- 

 markable memoir on Trypanosoma noctuce and Trypanosoma 

 ziemanni, and their relations with the Haemosporidia. The 

 latter organism (T. ziemanni) forms Spirochaete-like threads by 

 continued longitudinal fission, but these possess a condensed 

 nucleus. 



The same brilliant investigator, the late Dr. Schaudinn, in 

 collaboration with Hoffmann (11), also found a spirochaetiform 

 organism in syphilitic lesions, which form was called Spirochceta 

 pallida (10) at first. It is known now, more correctly, as Treponema 

 pallidum, for it has not been shown to possess a true undulating 

 membrane, and it is very long and thin, being only about '25/4 

 broad and some 14/4 in length. The spirals in it are preformed. 

 The ends of the body are finely tapering, and these long, thread- 

 like ends may be delicate, filamentous flagella (fig. 1, c). 

 Krzysztalowicz and Siedlecki describe a clear, oval area in the 



