TREPONEMA PALLIDUM 161 



Diagnosis. In the serum of a syphilitic certain anti- 

 bodies are formed that can be made use of in diagnosis. 

 This is the basis of the Wassermann test upon the 

 blood, due to antibodies like bacteriolysins. Its theory 

 and practice are too intricately technical to be included 

 here. Suffice it to say that it is certainly a positive 

 test in 95 per cent, of cases in which there exists 

 untreated syphilis. Proper treatment destroys the 

 Wassermann reaction, but whenever it results posi- 

 tively some form of syphilis is present, although it may 

 not be in a form transmissible to others. Otherwise 

 syphilis is diagnosticated by finding spirochetes in the 

 serum which exudes from ehancres, skin eruptions, 

 and mucous patches, or the venereal warts on mucous 

 membranes. This serum is taken and looked at 

 unstained upon a background of India ink or by w T hat 

 is called dark-field illumination, a process by which the 

 light is made to shine upon the body of the spiral from 

 the side. It can also be stained by appropriate methods, 

 but its minute size and paleness make this a trying test. 



Morphology and General Characteristics. The Spiro- 

 cheta pallida is a corkscrew-like, actively motile, 

 delicate thread. Its windings assume the form of a 

 large arc of a small circle, and vary from four to 

 twenty. It is TinnrTnr to TT^TTTT mcn wide and from 

 s~oVo to ToVo mcn long. It moves by end flagella, 

 in a screwing and waving motion. It is killed rapidly 

 by drying, a very fortunate thing, as many people 

 are thereby protected. Against weak bichloride and 

 carbolic acid it has no resistance. Alcohol will destroy 

 it in five minutes. Up until the beginning of 1911 no 

 success had met attempts to cultivate these spirals 

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