CLASSIFICATION OF THE MAIN SUBDIVISIONS 467 



ridge, commonly but wrongly termed an " undulating membrane," 

 running the length of the body. The type of the genus is C. bal- 

 bianii, originally named by Certes Trypanosoma balbianii, from the 

 crystalline style of the oyster. 



3. Saprospira, Gross (898), for free-living, saprophytic forms 

 similar in structure to Cristispira, but without the crest. 



4. Spiroschaudinnia, the name proposed by Sambon for the 

 many species of minute spirochaetes parasitic in the blood of verte- 

 brates and in various invertebrates. Such are S. recurrentis 

 (=obermeieri), parasite of human relapsing fever; S. duttoni^ 

 parasite of African relapsing fever; S. gallinarum of fowls; S. 

 anserina of geese ; and numerous other species from various hosts. 

 In structure the body of these species appears to be little, if any- 

 thing, more than a flexible thread of chromatin ; but the develop- 

 ment indicates rather that, as in the genus Cristispira, the interior of 

 the body is divided into minute segments or chambers. The species 

 parasitic in blood are transmitted by the agency of blood-sucking 

 arthropods. S. duttoni, for example, is transmitted by a tick 

 Ornithodoros moubata which lives in the mud-floors of huts or in 

 the soil in spots where caravans camp habitually. The spirochaetes 

 are taken up from human blood by the adult ticks, and pass through 

 the egg into the next generation of nymphs,* which transmit the 

 infection to human beings. 



5. Treponema, the name proposed by Schaudinn for T. pallidum, 

 the spirochaete of syphilis discovered by him. A second species 

 T. penenue, the parasite of yaws (framboesia) is also recognized. 

 Structurally this type is very similar to the last. 



Some authors for instance, Gross (899) and Dobell (895) consider that 

 there is " no valid reason for drawing a generic distinction between Treponema 

 pallidum and such forms as ' Spirochcefa ' recurrentis, etc.'* Gross combines 

 Types 4 and 5 under the name Spironema proposed by Vuillemin ; but 

 since this name is preoccupied, Dobell places them together in Schaudinn's 

 genus Treponema. 



The forms parasitic in the blood of human beings and other vertebrates 

 were generally regarded as Bacteria of the genus Spirillum, or at least of the* 

 section Spirillacea, until quite recent years, and the diseases caused by them 

 were spoken of as spirilloses. The chief points of difference between the 

 spirilla of relapsing fevers and those of the ordinary type were the flexibility 

 of the body in the former and the failure to grow them in cultures. The con- 

 fusion prevailing at present originated with Schaudinn's famous memoir on 

 the blood-parasites of the Little Owl (132). While, on the one hand, it is to 

 Schaudinn's credit to have recognized the affinities of the parasitic " spirilla " 

 to Ehrenberg's free-living genus Spirochceta he was, on the other hand, misled 

 by the superficial resemblance between spirochsetes and certain small, slender 

 forms of trypanosomes, which again he connected, quite erroneously, with 

 the life-cycle of Leucocylozoon (see p. 370). Schaudinn therefore regarded 

 the spirbchaetes as Protozoa allied to trypanosomes, and endeavoured to 

 prove a similar type of organization in both classes of organisms : a nuclear 



* The six-legged larval stage is suppressed that is to say, passed through in 

 the egg in this species of tick. 



