720 



Sj^hilis 



1. Cover the smear with a i per cent, aqueous solution of osriiic acid, and per- 

 mit it to act for thirty seconds. This solution acts as a fixative and mordant. 



2. Wash thoroughly in running water. 



3. Cover the smear with a i : 100 dilution of Liquor plumbi subacetatis (freshly 

 prepared). Permit it to act for ten seconds. The lead unites with the albumin 

 to form lead albuminate which is insoluble in water. 



4. Wash thoroughly in running water. 



5. Cover the smear with a 10 per cent, aqueous solution of sodium sulphid. 

 This is to act ten seconds, during which the salt transforms the lead albuminate 

 into lead sulphid and causes the preparation to turn brown. The osmic acid 

 when reapplied causes it to become black. 



6. Wash thoroughly in running water. 



The whole process is to be repeated in exactly the same manner 

 three times, the washings all being very thorough. The preparation 

 is then dried and mounted in Canada balsam. The micro-organisms 

 and cellular detritus are stained black. 



Fig. 295. — Treponema pallidum in the periosteum near an epiphysis (Bertarelli). 



When serum from a primary sore or other syphilitic lesion is treated 

 by these methods, a number of the spirochaeta appear well stained 

 and a number very palely stained, so that one is in doubt whether 

 there may be many others unstained, and this seems to be the case, 

 for when similar smears are treated by other methods many more 

 can be found. 



Stern* has applied the method of silver incrustation to the ex- 

 amination of films 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 ovenat 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 brown- 

 ish metallic in appearance, when they are thoroughly washed in water. The spi- , 

 rochseta appear black, the background brownish. 



* "Berliner klin. Wochenschrift," 1907, No. 14. 



