THE ANIMAL PARASITES OF MAN 



C. 



THE SPIROCH^TES. 



The Spirochaetes are long, narrow, wavy, thread-like organisms, 

 with a firm yet flexible outer covering or periplast. There is a diffuse 

 nucleus internally in the form of bars or rodlets of chromatin 

 distributed along the body. In some forms there is a membrane or 

 crista present (fig. 53), which in the past was compared with the 

 undulating membrane of a trypanosome, but the membrane of a 

 spirochaete does not undulate. Progression is very rapid, corkscrew- 

 like and undulatory movements occurring simultaneously. 



The genus Spirochceta was founded by 

 Ehrenberg in 1833 for an organism which 

 he discovered in stagnant water in Berlin. 

 Ehrenberg named the organism Spirochceta 

 plicatilis. According to Zuelzer (1912) S. 

 plicatilis does not possess a membrane or 

 crista, but an axial filament. S. gigantea has 

 been described by Warming from sea- water. 



Spirochaetes occur in the crystalline style 

 and digestive tract of many bivalve molluscs. 

 The first molluscan spirochaete to be studied 

 was that of the oyster, named by Certes (1882) 

 " Trypanosoma " balbianii (fig. 53). Similar 

 spirochaetes, probably belonging to the same 

 species, occur in various species of Tapes and 

 in Pecten (the scallop). S. balbianii has rounded 

 ends (fig. 53). Other spirochaetes occur in fresh- 

 water mussels (Anodonta spp). .S. anodontce, 

 studied by Keysselitz (1906) and by Fantham 

 (1907), has pointed ends. Gross (1911) sug- 

 gested the generic name Cristispira for mol- 

 luscan spirochaetes, because they possess a 

 well-marked membrane or "crista," which 

 appears to be absent from S. plicatilis, accord- 

 ing to Zuelzer's researches. 



Schaudinn in 1905 founded the genus 

 Treponema for the parasite of syphilis (T. 

 pallidntn), discovered by him and by Hoffmann. 

 According to Schaudinn the Treponemata have no membrane or 

 crista. The pathogenic agent of yaws or framboesia, discovered by 

 Castellani, is also placed in the genus Treponema, as T.pertenue. 



There remain the blood spirochaetes. It is somewhat disputed as 

 to whether these organisms possess a membrane. The present writer 

 considers that they have a slight membrane or crista. The name of 



f;::=d. 



FIG. 53. Spirochata bal- 

 bianii. a, basal granule or 

 polar cap. />, chromatin rod - 

 lets, c, membrane (' crista"). 

 d, myonemes in membrane. 

 {After Fantham and Porter.) 



