86 LABORATORY BACTERIOLOGY 



serum from a -typhoid patient, or the blood of an immune 

 guinea pig, and immediately make a hanging-drop prepara- 

 tion with a loopful of the mixture and examine. Note the 

 effect on the motility of the bacilli and their aggregation into 

 clumps. Specify the time elapsing before the agglutination 

 appears and the time required for the complete clumping. 



Make a similar examination of a culture to which i/io 

 blood serum has been added. 



Repeat the above test with the blood from animals affected 

 with or immunized against hog cholera. 



Examine a dried specimen of blood for this reaction. Add 

 a few drops of bouillon or water to the drop of dried blood on 

 a slide, and after it has become well mixed add a loopful of it 

 to a similar quantity of a fresh bouillon culture and examine 

 it immediately in a hanging drop. 



Inoculate the media in Groups A and B with the culture 

 iirnished of B. septicaemia hemorrhagicce, or M. lanceolatus, 

 or both, as directed. 



128. Securing blood for the widal test, (a) Preparation of 

 dried blood. Prick the finger or lobe of the ear (if a lower 

 animal, the shaved ear is a good place) sufficiently deep to 

 procure a drop of blood. Place it on a slide by means of a 

 platinum loop and allow it to dry. 



(b) Fresh blood. Procure a drop of blood as in (a) ; add 

 to it 10 drops of water on a glass slide or in a small test tube. 

 Stir until the blood is dissolved. One loopful of this mixed 

 with a similar quantity of the bouillon will give a dilution of 

 i to 20. 



(c) Serum. From a similar but deeper prick, or by draw- 

 ing a few drops of blood from a vein with a hypodermic syringe, 

 secure a few drops of blood. Place them in the bottom of a 

 small, short, sterile tube and allow the serum to ooze out. 

 This can often be helped by separating the blood from the 

 tube by means of a sterile wire. If retained for any length 

 of time before making the test, the serum must be kept in a 



