6 4 



PROTOZOA AND DISEASE 



tion, it is only necessary to refer to the salient characters of 

 Spironema luis. Its slenderness and low power of refracting light, 

 associated with the characteristic form of the spiral, which is narrow, 

 deep, regular, and has usually from ten to twenty-six turns (see 

 Fig. 20), serve to distinguish it from other objects. One great 

 feature is that in the living state the organism exhibits this typical 

 form not only when in motion, but also when at rest. Other spiro- 

 chaetae become more nearly straight when they come to rest. It 

 is noteworthy that no increase in numbers of the spironema has 

 been obtained in artificial culture media. Schaudinn and Hoffmann 1 



FIG. 20 bis. SPIROCH^ET^E. (After Schaudinn.) 



i, Spirochcsta refringens,2i common spirochaete ; 2, Sp. (spironema) pallida of 

 syphilis ; 3, Sp. pallida of syphilis (?) dividing. 



found that the addition of glycerine caused various changes in the form 

 of living spironemata. Some remained cork-screw-shaped for from 

 five to ten minutes and then disappeared ; others lost their spirals 

 and became straight, then gradually drew themselves together and 

 assumed the shape of a malaria sporozoite, and this in some instances 

 became short and ovoid. Similar bodies were found in cover-glass 

 preparations untreated by glycerine. 



So important was the discovery of the 5. luis that, as re- 

 corded in an already voluminous literature, many workers applied 

 themselves to search for the parasites in syphilitic lesions of all 

 1 Schaudinn and Hoffmann, Arbeit, aus der Kais. Gesund., 22, 1905. 



