114 



MICROSCOPIC METHODS 



make a number of these capsules at one time and to draw off 

 their extremities and seal them in the flame. For use the tips of 

 both extremities are broken off, the finger is pricked, and blood 

 allowed to pass into the capsule through the bent limb till 

 the capsule is about half full. The air remaining in the capsule 

 is rarefied by passing the straight end through a flame and 

 then sealing it off. By this manipulation the blood is sucked 

 over the bend into the straight part of the tube, and the bent 

 end is now also sealed off or closed with wax. It is well to 

 shake the blood down towards the closed straight end, care being 

 taken to previously allow the glass to cool sufficiently. The 

 capsule is now hung by the bend on the edge of a centrifuge 

 tube 'and the serum separated by spinning the instrument. In 

 any particular case a capsule of serum 

 from the infected person and one from 

 a normal individual are prepared. 



The emulsion, corpuscles, and serum 

 being thus prepared, the next step is 

 to mix them. This is done by taking 

 a piece of quill tubing and drawing it 

 out to a capillary point so as to make 

 a pipette about eight inches long ; on 

 the thick end of this a rubber teat is 

 fixed, and about one inch from the 

 capillary point a mark is made with 



FTG. 47. -Wright's Blood-cap- an oi f P enciL From the watch-glass 



sule and method of filling containing the separated leucocytes a 



same. portion is sucked up to the mark and 



then an air-bubble is allowed to pass 



in. A similar portion of the serum is drawn up, and then another 

 air-bubble, and finally a similar portion of the bacterial emulsion. 

 The three droplets are carefully blown on to a slide and are 

 thoroughly mixed with one another by being alternately 

 drawn up into the tube and expelled several times. The 

 mixture is then drawn into the tube and the end sealed off in the 

 flame. The rubber nipple is removed and the tube placed in the 

 incubator at 37 for fifteen minutes. A slide is now prepared 

 by rubbing it once or twice with very fine emery paper 

 (No. 000) and thoroughly wiping it. This ; is a procedure 

 adopted by Wright to cause an evenly distributed film to be 

 made. The tube being removed from the incubator and the 

 end broken off, its contents are again mixed by expelling 

 and drawing up into the tube. A minute droplet is placed 

 on the prepared slide, and by means of the edge of the end 



