490 HANS ZINSSER AND J. G. HOPKINS 



It was startling to find this organism growing only when syphi- 

 litic material had been planted, and then multiplying with sparse- 

 ness and cultivated with difficulties much greater than those at- 

 tending the eventual cultivation of the limited number of strains 

 of T. -pallidum successfully grown by various workers. However, 

 the obvious suspicions as to its connection with the syphihtic 

 lesions aroused by these, facts seemed easily refuted by the morph- 

 ology of this treponema which is very different from that of both 

 the virulent treponemata and of the cultivated T. pallidum de- 

 scribed by Miihlens, Noguchi, and others, and studied for several 

 years by us. 



The microorganism is a very fine spiral with curves having the 

 absolute regularity of a corkscrew in most of the individuals, 

 with finely tapering ends, and varying in length from 2 to 10 or 

 20 rather shallow curves. Both short and long forms are from 

 two to three times as thick as the Treponema pallidum, and in 

 most individuals a definite double contour is visible. The aver- 

 age length varies from about one-half to three or four times that of 

 the Treponema pallidum and occasional long forms are seen which 

 extend completely across the dark field of a one-twelfth oil im- 

 mersion lens. The curves are long and shallow. 



What is most noticeable about these treponemata is their ab- 

 solute rigidity and lack of any kind of motility. At first we took 

 H for granted that the organisms were dead. However, when 

 we found that subsequent generations in culture were equally 

 immobile, it became evident that this was characteristic of the 

 species. 



The organism stains with great difficulty. Its contours ap- 

 pear faint and are often less distinct than those of the Treponema 

 pallidum after 12 hours staining in dilute Giemsa. It can be dem- 

 onstrated with the Loeffler flagella stain and by the Fontana 

 method. We have so far failed to stain it with the ordinary dyes. 



Cultivation is extremely difficult. As stated above, multi- 

 plication has appeared in ascitic agar tubes prepared with rab- 

 bits' kidney as in the Noguchi method. We have had three or 

 four strains which have proceeded to the third or fourth genera- 

 tion only to be lost. At present we have a strain still growing 



