THE WASSERMANN REACTION 501 



contains from six to fourteen and sometimes twenty or more turns. 

 This measurement of the length of the spiral is usually possible, 

 and is of the greatest value in identifying the treponema. 



2. Stained preparations. Smears from chancres, etc., may be 

 stained by the Giemsa method. 



The smears are fixed for ten minutes in absolute alcohol. The 

 preparations are then stained in a dilute solution of the Giemsa 

 solution for two to twenty-four hours, washed in distilled water, 

 dried, and mounted. (The dilute Giemsa is prepared by adding 

 one drop of the Giemsa stain to a cubic centimetre of distilled water, 

 and rendering alkaline with one drop of 0-01 per cent, potassium 

 carbonate solution.) The preparations may also be stained in the 

 undiluted Giemsa stain for half to six hours. Leishman's solution 

 may also be used or the Giemsa method described under " Malaria." 



Sections may be stained by Levaditi's method : 



(1) Fix pieces of tissue about 1 mm. thick in 10 per cent, formalin 

 for twenty -four hours. 



(2) Wash in water, and harden in 96 per cent, alcohol for twenty- 

 four hours. 



(3) Wash in distilled water for some minutes (until pieces sink). 



(4) Place in 3 per cent, silver nitrate solution at 37 C. for three 

 to five days in the dark. 



(5) Wash in distilled water for some minutes, and then place 

 in the following solution at room temperature for twenty-four to 

 forty-eight hours. 



Pyrogallic acid ...... 2-4 grm. 



Formalin ....... 5 c.c. 



Distilled water . . . . . 100 c.c. 



(6) Wash in distilled water, dehydrate in absolute alcohol, clear 

 in xylol, embed in paraffin, cut, and mount. 



The spirochaetes are stained black or brown (Plate XXIII. a), 

 the tissues yellow. 



Some have asserted that the spirochaetes seen in the tissues after 

 staining by this method are artifacts or are composed of filaments 

 of elastic tissue. 1 



3. The Wassermann reaction or antigen test. This is applied in 

 the diagnosis of syphilitic conditions, and as a confirmatory test 

 of the syphilitic nature of such conditions as tabes dorsalis and 

 general paralysis of the insane. The test is based on complement- 

 fixation (p. 183). In this method an " antigen " consisting of 

 micro-organisms, or an extract thereof, fixes its homologous immune- 



1 See Saling and Miihlens, Centr. f. Bakt. (Orig.), xlii and xliii. 



