218 THE PATHOGENIC FLAGELLATES 



29th Genus. Spirillum : Animal e familia Vibrioniorum divisione 

 spontanea imperfecta (et obliqua ?) in catenam tortuosam S. cociileam 

 rigidam et in cylindri formam extensam abicns.' 



This first description of the organism which Ehrenberg named 

 spirocheta is certainly very meagre and not much more enlightening 

 for present-day purposes than the spirilliform figures of Kohler, 

 published in 1777, or the crude descriptions and figures of similar 

 forms by O. F. Miiller, in 1786. The essential point of difference 

 between the genus spirocheta and the genus spirillum was the rigidity 

 or inflexibility of the latter as against the flexibility of the former. 

 Schaudinn, in 1905, added another point to the diagnostic character- 

 ization of the genus by describing a deflnite undulating membrane. 



Spirocheta thus characterized as an organism with flexible, spirally 

 twisted body with laterally placed undulating membrane, would seem 

 to be definitely distinguished from the genus spirillum with rigid cork- 

 screw-like body and no membrane; but, unfortunately, the problem is 

 not so simple, for we have to do with exquisitely minute things which 

 offer extreme difficulties in technical treatment and require carefully 

 trained eyes. Statements as to structure and activities of certain 

 species, even though made by equally eminent authorities, are fre- 

 quently directly contradictory, and only too often the individual 

 prejudices are so strong as to weaken the scientific value of the obser- 

 vations. 



Schaudinn's discovery, in 1905, of the organism of syphilis, Trepo- 

 nema (^Spirocheta) pallidum, was the direct inspiration to thousands 

 of investigators to study anew the old forms and to penetrate unknown 

 fields of pathology in the hope of finding and describing new forms. 

 As a consequence of this activity, the systematist today is confronted 

 with a most heterogeneous collection of spirilliform organisms, and is 

 forced to wade through a most conflicting tangle of observations and 

 deductions. The descriptions of organisms which have been classified 

 as spirocheta are often obviously far from the original type of Ehren- 

 berg, so far, indeed, as to justify new generic names. Some of them 

 differ in having flagella (of the spirilla type) at one or at both ends; 

 others have multiple flagella so called; and still others have neither 

 membrane nor flagella. These discrepancies have been widely recog- 

 nized and new generic names have been proposed and, in some cases, 

 accepted. Some observers, on the other hand, have made the mistake 

 of basing genera on physiological lines alone, and these, like the genus 

 spiroschaudinnia of Sambon, based upon the fact of change of hosts, 

 will not be accepted. 



Observations are too incomplete and too often contradictory to 

 justify a safe grouping at the present time, and in making groups of 



' Ehrenberg, Die Infu^ionathierschen, etc., 1838, p. S3, 84 



