790 



Syphilis 



has applied it with great success to the examination of 

 fluids by the following simple procedure: Spreads are made 

 in the usual manner, dried in the air, and then for a few 

 hours in an incubating oven at 37 C. They are next 

 placed in a 10 per cent, solution of nitrate of silver in a 

 colorless glass receptacle and allowed to rest in the diffused 

 daylight of a comfortably lighted room for a few hours, until 

 they become brownish metallic in appearance, when they 

 are thoroughly washed in water. The spirochaeta appear 

 black, the background brownish. 



Fig. 259. Treponema pallidum in the periosteum near an epiphysis 



(Bertarelli). 



Staining the organism in the tissues was found to be a more 

 difficult matter, for the Giemsa stain scarcely showed it at all. 

 Bertarelli and Volpino* endeavored to stain sections by a 

 modification of the van Ermengen method for flagella and 

 had some success, but the demonstration of the organisms 

 in tissue was not really successful until Levaditif devised 

 the method of silver impregnation. This consists in hard- 

 ening pieces of tissue about i mm. in thickness in 10 per 

 cent, formol for twenty-four hours, rinsing in water, and 

 immersing in 95 per cent, alcohol for twenty-four hours. 



' "Centralbl. f. Bakt. u. Parasitenk.," Orig., 1905, XL, p. 56. 

 f "Compt.-rendu de la Soc. de Biol. de Paris," 1905, ux, p. 326. 



