SPIROCHJETA PALLIDA. 207 



SPIROCILETA PALLIDA. 

 Treponema Pallida. 



History. Schaudinn and Hoffman in 1905 discovered in 

 primary and secondary lesions of syphilis spirochaetse differ- 

 ing considerably from the previously known ones. He called 

 them Spirochceta pallida (Plate VI, Fig. 1). On account of 

 his belief in their animal nature he has since renamed them 

 Treponema pallida. 



Morphology and Staining. The Treponema pallida is dis- 

 tinguished by its extreme thinness and the acuteness of its 

 curves or spirals, which are almost angular and usually aver- 

 age ten in number. In fresh preparations, seen best with the 

 aid of a dark field illumination, they are observed to be very 

 active, their motion being mostly of a rotary character, though 

 occasionally they may be seen to bend on themselves. The 

 Treponema pal/Ida measures from 4-10 p. in length, and rarely 

 exceeds 0.5 p in width. 



The Treponema pallida are best demonstrated in fresh prep- 

 arations. The aid of a condenser for dark field illumination is 

 almost a necessity, although sometimes under favorable condi- 

 tions they may be demonstrated with an ordinary condenser 

 with the diaphragm closed as for urine work. The spirochsetse 

 are very refractile and show as glistening, undulating threads. 

 For this method of examination, as well as for making smears, 

 it is necessary to obtain the material from the deeper layers of 

 tissue, using a curette if necessary. The admixture of blood- 

 corpuscles should be avoided, as the serum is best. For mak- 

 ing stained preparations all the ordinary blood stains are useful, 

 Giem.sa's method being probably the best. The Treponema pal- 

 lida does not stain with the ordinary anilin dyes. If a drop of 

 India-ink and a drop of syphilitic material be mixed and a 

 smear made and allowed to dry, the Treponema pallida will 

 show unstained on a contrasted black background. For begin- 

 ners with untrained eyes this is an uncertain method, and must 

 not be recommended to any one except for its quickness. 



Schaudinn described a larger, coarser, more highly refractik 

 spiral which he afterward found in company with the Trepo- 



