SYPHILIS 93 



titioner who is only occasionally called on to make the diagnosis. 

 The idea is simple and ingenious. The material supposed to 

 contain spirochsetes is mixed with Indian ink, which consists of 

 an emulsion of fine particles of carbon. As the film dries these 

 settle down on each side of the spirochaetes (or any bacteria, etc., 

 which may be present), so that when the specimen is examined 

 microscopically, the light is prevented from passing, except that 

 which goes through the organisms, so that these are seen as 

 transparent bodies on a dark ground. 



The details of the process are as follows : The best ink to use 

 is that sold for the purpose as Burri's ink, or " Pelikan-tusche, 

 No. 541." It can be obtained from any of the agents for 

 Griibler's stains. Shake it well before use, and mix (with a 

 pipette or platinum loop) i part with 4 parts of normal saline 

 solution or water. Take one loopful of the serum from the sup- 

 posed chancre, etc., and mix it intimately on a clean slide with 

 the same amount of the diluted ink. Spread it out in a thin film, 

 and allow it to dry. Considerable experience is necessary to get 

 the right thickness, and until this is acquired it is a good plan to 

 prepare films which vary greatly in this respect in different parts, 

 some of which will be sure to be about right. When dry apply 

 cedar oil, and examine under the j\-inch immersion lens. Fixa- 

 tion is unnecessary. 



I can strongly recommend this method. It is simple and easy, 

 and very nearly, though not quite, as good as the optical dark 

 background method. For beginners I think it much more trust- 

 worthy than any of the staining processes. 



3. Staining Processes. — For any of these spread the material 

 obtained as previously described in a very thin layer on a scrupu- 

 lously clean slide, allow to dry, and fix by gentle heat— »'.«., such 

 that it does not get uncomfortably hot to the finger. 



Prepare a mixture of 10 c.c. tap-water (or of distilled water 

 + I drop of a I in 1,000 solution of potassium carbonate) and 

 10 drops of Giemsa's stain, which must be bought ready pre- 

 pared. In mixing the two avoid violent agitation ; add the stain 

 to the water in a test-tube, stopper the latter with your thumb and 

 invert it slowly once or twice. Do not mix it until you are ready 

 to proceed with the staining. 



Take the slide in a perfectly clean pair of forceps, flood it with 

 the stain, and heat until it just begins to steam ; remove it from 

 the flame and in fifteen seconds pour off the solution, replace it 



