DETECTION OF THE PARASITE 733 



Lymphatic glands. Puncture the gland with a large-bored needle and 

 aspirate the juice with a sterile syringe. 



Blood. Examination of blood-films generally gives negative results, so 

 that it is desirable to select one or other of the following special methods in 

 searching for the parasite. 



Nattan-Larrier and Bergeron's method. 1. Collect 10 c.c. of blood from a 

 vein at the bend of the elbow (p. 193). 



2. Distribute the blood into two flasks each containing 100 c.c. of distilled 

 water. 



3. Let the blood hsemolyze and then centrifuge. 



4. Prepare thin films with the centrifuged deposit. Dry. Fix in a mixture 

 of alcohol-ether. 



5. Stain by Bertarelli's method (p. 730) ; or with Heidenhain's iron 

 hsematoxylin. 



Ravaut and Ponselle's method. 1. Let the blood fall, drop by drop, into 

 30 c.c. of distilled water. 



2. Collect the clot, wash it, blot, harden, stain by Levaditi's method and 

 cut like an histological preparation. 



Nseggerath and Staehelin's method. 1. Collect about 1 c.c. of blood in a 

 tube containing a 0'33 per cent, aqueous solution of acetic acid. 



2. Leave the blood to hsemolyze. Centrifuge. 



3. Prepare films with the deposit. Dry. Fix and stain by Giemsa's slow 

 method. 



2. Methods of examination. 



In examining material for the Treponema pallidum it is always necessary 

 to bear in mind that in many syphilitic affections (ulcerated chancres, mucous 

 plaques, suppurating gummata, etc.) other micro-organisms are present in 

 addition to the specific parasite, so that, if a spirochsete be found, great care 

 must be exercised to make certain that the one seen is in fact the Treponema 

 pallidum, because numerous other spirochsetes, differing more or less from the 

 specific spirochaete of syphilis, are often found in the tissues (vide infra). 



I. Examination of fresh material. The examination of fresh material is 

 very unreliable ; the extreme tenuity of the organism and its feeble powers 

 of refraction render its detection difficult and demand very acute powers of 

 observation on the part of the investigator. It was, however, by this method 

 that Schaudinn discovered the treponema. 



Scholtz recommends examining the material in a hanging-drop preparation. 

 The sweated serum or scrapings, rubbed up in a drop of normal saline solution, 

 are examined in a cell or between a slide and cover-glass. Fluid from a 

 pemphigus bulla and blister fluid should be examined in the same way. 



The material must be examined by artificial light (an inverted incandescent 

 burner (p. 118) is very useful) and with an oil-immersion lens (Levaditiand 

 Roche). 



II. Examination with dark-ground illumination. This is not only the most 

 rapid but perhaps the most reliable method for finding the treponemata 

 (Landsteiner and Mucha, Gastou). 



Arrange the dark-ground illuminator as directed on p. 125. If an oil- 

 immersion lens be used place a diaphragm in the objective, but a high power 

 dry lens is quite suitable. An inverted incandescent burner or Nernst lamp 

 is a good source of light. Everything being in order, place the drop of fluid 

 either pure or diluted in a little normal saline solution between the slide 

 and cover-glass (for details vide p. 127). 



Under these conditions, the treponema stands out brightly against the 

 black back-ground of the preparation (fig. 344) and is easily seen. The most 



