HIDEYO NOGUCHI 455 



The question whether spirochetes are plants or animals is to my mind still an open 

 one. The absence of polarity and of any definite nucleus and the mode of multipli- 

 cation (by transverse fission) all point to a relationship with the bacteria. On the 

 other hand, the spirochetes, and particularly those belonging to the pallidum, re- 

 currentis, and icterohaemorrhagiae types, appear to form granular elements the sig- 

 nificance of which is still under discussion. The observations of Leishman,' Balfour,' 

 NuttalV Hindle,'' Blanc,^ Fantham,*^ and others on the granule stage of T. duttoni in 

 the body of ticks seem to me to prove beyond any doubt that these organisms under- 

 go a granular evolution after ingestion by the tick in the course of which in about 

 ten days there emerges a large number of young, active spirochetes, thinner, smaller, 

 and more difficult to stain than the blood form. Such a phenomenon has never been 

 known to occur in bacterial organisms. Martin and Pettit^ have observed granular 

 forms in cultures of L. icterohaemorrhagiae. In the case of L. interrogans,^ cultures 

 containing only granular forms have been proved capable of infecting guinea pigs 

 with reappearance of the spiral form in the animals. A similar phenomenon was re- 

 corded by the writer in the case of T. pallidum in 1911-12.' The filterability of the 

 spirochetes is another property which distinguishes them from the bacteria. The 

 ciuestion of the phylogenetic relationship of the spirochetes is therefore not an easy 

 one to settle. 



FAMILY SPIROCHAETACEAE 



Unicellular, spiral, filamentous, highly flexible organisms. Transverse division by fission, 

 usually binary, the daughter-cells being held together for some time to form chains of two 

 or more individuals. In cultures a long thread of several individuals joined by thin bridges 

 is not uncommon. The apparatus of motion consists of an elastic axial filament or a modified 

 fibrillar membrane along the side of the cell body, which serves to produce a propelling effect 

 when contracted and relaxed by successive contraction and relaxation of the contractile 

 bank (myonemes?) imbedded in the outer layer of protoplasm. 



Genus Spirochacta {Ehrcnberg, 1834; Zuelzer, igio). — Unicellular, flexible, membrane in- 

 distinct, long cylindrical filament composed of a straight elastic axial filament surrounded 

 by a layer of alveolar protoplasm spirally coiling about the axial filament (Figs. 2, 3). Creep- 

 ing movements. No terminal flagella demonstrated. Volutin granules distributed in pairs 

 at each turn of the protoplasmic spirals. Transverse and multiple division. 



Spirochacla plicatilis {Ehrcnbcrg, 1834). — Stagnant water; free living; requires hydrogen 

 sulphide for growth. 



Genus Treponema {Schaudinn, igoj). — Long, slender, cylindrical, spirally wound, high- 

 ly flexible cell body, which exhibits serpentine, corkscrew-like, and sometimes lashing move- 

 ments. The spiral curves are alternately stretched and relaxed with a certain regularity. 



'Leishman, W. B.: Lancet, 128, 11. 1910; Tr. Soc. Trap. Med. cr Hyg., 3, 77. 1910; Intcr?ial. 

 Cong. Med., 21, 282. 1913. 



^ Balfour, A.: Rep. Wellcome Research Lab., KJiartoum, 3, 35. igoS; ibid., 4, 76. 191 1; Internal. 

 Cong. Med., 21, 275. 1913. 



^ Nuttall, G. H. F.: Harvey Lectures, p. 28. 191 2-13. 



•t Hindle, E.: Ann. Trap. Med., 4, 463. 191 1. 



5 Blanc, G. R. : Theses de Paris, No. 432. 1910-11. 



'Fantham, H. B.: Ann. Trap. Med., 8, 471. 1914. 



7 Martin, L., and Pettit, A.: Spirochetose Icterohaeinorragiqite. Paris, 1919. 



^Noguchi, H.: /. E.xper. Med., 30, 26. 1919. ' Noguchi, H.: Prcssc nied., 21, 801. 1913. 



