328 PUBLIC HEALTH BACTERIOLOGY 



regular spiral turns close together, the whole resembling 

 a fine corkscrew. It has a flagellum at each extremity, 

 but no undulating membrane. It multiplies by longi- 

 tudinal division, the initial stage being shown by the 

 splitting of the flagellum at one end. It can be demon- 

 strated in the living state in a hanging drop, or a ringed-in 

 cover-slip, cutting down the light to a minimum, or better, 

 by using dark-field illumination. In smears, it can be 

 stained by Giemsa's method, of which there are several 

 modifications. -A more rapid and simple method is by 

 using India ink. A loopful of secretion from a chancre is 

 mixed with a loopful of ink (Gunther & Wagner's liquid 

 pearl ink), and the mixture made into a smear as for blood. 

 Dry in the air, and examine with an oil-immersion lens. 

 The treponemata appear as white spirals on a dark back- 

 ground. In tissues, ordinary methods do not stain the 

 organisms. Levaditi's method is commonly used, and 

 consists in fixing in formalin for 24 hours, washing out the 

 formalin with water, the traces of which, which might con- 

 tain formalin, being removed with alcohol ; soak in silver 

 nitrate solution for from three to five days, wash and soak 

 in pyrogallol-formalin solution ; wash, dehydrate, imbed in 

 paraffin, and section. A shorter method has been devised. 

 The evidence of its pathogenicity is derived from its 

 constant presence in the lesions of acquired and congenital 

 syphilis, and in that it has been communicated to monkeys, 

 producing typical syphilitic course and lesions, from which 

 the treponema was recovered in 70 per cent of the cases 

 examined. It has not yet been successfully cultivated in 

 a pure state, or in that case complement fixation by a 

 pure culture might be an additional proof. It is not 

 regularly recovered from tertiary lesions, which is not 

 surprising. This is analogous to tuberculosis, in which 

 the tubercle bacillus is often not demonstrable by ordinary 

 methods in the chronic lesions. Treponema pallidum 

 does not pass through a filter. 



Wassermann Reaction Is now regularly used in clinical 

 diagnosis. It is described on page 205 ; its value is 

 discussed on page 209. In a recent research by Calmette, 

 Breton, and Couvrer, it has been practically applied 

 to the diagnosis of syphilis in the newly born child, 



