Morphology Staining 



801 



Malabar, Assam, Ceylon, Burraah, Siam, Malay Peninsula, 

 the Indian Archipelago, Moluccas, and China. It is also 

 endemic in many of the islands and archipelagos of the 

 southern Pacific. 



The cause of the disease was unknown until the discovery of 

 Treponema pallidum, which opened a way for its investiga- 

 tion. Castellani* was quick to seize the opportunity, and in 

 the same year in which Schaudinn and Hoffmann discovered 

 the cause of syphilis, announced a similar organism as the 

 cause of yaws. At the time of discovery he called it Spiro- 



Fig. 261. Yaws (photograph by P. B. Cousland, M. B., Swatow, 



China). 



chaeta pertenuis and Spirochaeta pallidula, but it is now recog- 

 nized as a treponema and is called Treponema pertenue. 



Morphology. The organism so closely resembles Tre- 

 ponema pallidum that it is rather by knowing the source 

 from which the organism was derived than by any morpho- 

 logic distinctions that the two are separated. It measures 

 7 to 20 ft in length, is closely and regularly coiled, and is said 

 to have rounded ends. 



Staining. It stains like its close relative, palely with 

 most of the dyes. The silver nitrate, the India ink methods, 

 and the other methods of staining Treponema are all ap- 



*"Brit. Med. Jour.," 1905, n, 282, 1280, 1330. 



