614 A MANUAL OF BACTERIOLOGY 



(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 XXVI, fc), 

 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, but this is not the general opinion. 



B. THE WASSEKMANN KEACTION. 



For carrying out the Wassermann reaction the method of Fildes 

 and Mclntosh * will be described, with some additions and com- 

 ments (within square brackets) by the author, who has found it to 

 be convenient, accurate and relatively simple. In this method the 

 unit volume is 0-1 c.c. (though 0-05 c.c. may be used) and a total 

 of sixteen unit volumes is used in the test. 



A " small volume " technique for the same method will also be 

 described. 



I. COLLECTION OF THE SERUM, ETC., TO BE TESTED. About 

 0-5 c.c. of blood is required. This is easily collected from the 

 finger or thumb. The patient swings his right arm rapidly in order 

 to drive the blood into the finger tips ; a piece of fairly thin 

 drainage tubing is then twisted round the thumb and two or three 

 punctures are made with a glass " pricker " or surgical needle 

 just proximally to the nail and towards the ulnar side. The blood 

 is collected in a Wright's capsule of suitable size. Fuse the straight 

 end of the capsule. Attach a gummed label inscribed with the 

 number of the case and enter up the particulars in the book under 

 the same number. Put away the capsule into an efficient ice chest 

 until required. 



If an efficient ice-chest is not available, or if the specimen has 

 been sent by post or badly collected, it is preferable to centrifuge 

 at once and pipette off the serum from the clot. 



The greatest care must be exercised to label the specimens arid 

 to " book " the particulars correctly, and to avoid any possibility 

 of error. 



1 Lancet, vol. ii, 1916, p. 751. Also Special Rep., No. 14, 1918, Medical 

 Research Committee, where three other methods are also given, with full 

 details. 



