SYPHILIS II/ 



solution to cause slight permanent turbidity. If you add too 

 much the solution will become clear again, and this is useless. 

 A very small amount only is required, and it can be added 

 conveniently with a platinum loop. 



(4) Distilled water. 



Process. (i) Prepare the films as already described, and 

 allow them to dry spontaneously. 



(2) Fix by pouring on the fixing fluid and pouring it off 

 after a few seconds. Renew it immediately, and continue 

 with the process several times. The total duration of this 

 stage should not be less than a minute. 



(3) Wash well in distilled water. 



(4) Flood with the mordant, apply g'entle heat until steam 

 rises, and allow the process to go on for half a minute. 



(5) Wash thoroughly (15-30 seconds) in distilled water. 



(6) Flood with the silver solution, again warm gently for 

 half a minute, wash, blot, and dry. Mount in balsam if you 

 want permanent specimens, as cedar oil causes the spirochaetes 

 to pale. 



This is a very excellent method. The spirochaetes are 

 stained jet-black, and appear larger than when stained by 

 ordinary methods; they can readily be seen with a -J-inch. 

 The process is really an easy one, and a considerable amount 

 of latitude is available in the duration of the various stages. 

 The most important point is the proper preparation of the 

 silver solution. 



In making the search a good lens and good light are 

 always, and much patience frequently, necessary; the 

 spirochaetes may be but one or two on a film, or there may 

 be several on one field of the microscope. Very occasionally 

 they are matted together in a dense mass. Having found a 

 spirochaete, proceed to see if it resembles the pallida or the 

 refringens; note especially its length (comparing it with a 

 red blood-corpuscle) and the number of turns of which this 

 distance is made up. If there are about six or eight turns 

 to this distance, it is almost certainly pallida; if there are 

 fewer, it is not. Examine its ends, and see whether they 

 taper off to a point or terminate abruptly. 



It is also possible to see the spirochaete unstained, when it 

 is actively motile, but it is not possible to distinguish it from 

 its congeners in this way without much practice. In point of 



