172 PRINCIPLES OF VETERINARY SURGERY 



a young culture about i8 hours old. OM cultures, or even 

 dead bacteria, will do. Take a platinum-loopful of these 

 known cholera bacilli and place upon the centre of a cover- 

 glass. Dilute the suspected blood with distilled water from 

 50 to 100 times. This can be done by mixing the blood 

 and water on a slide until the desired dilution is obtained. 

 Then add a loopful of this diluted blood to the bacteria on 

 the cover-glass. Take this cover-glass and turn it, loaded 

 side down, on a concave slide which has first been rimmed 

 with vaseline around its concavity, thus making an air- 

 tight chamber. Care must be taken not to mix the drop 

 with the vaseline or allow it to dry. Place the slide under 

 the microscope, using the oil-immersion lens. The proce- 

 dure is the same as that of the ordinary hanging-drop 

 method. Upon examining the slide, the bacilli will be seen 

 to be motile and moving about if a live culture has been 

 used; if a dead culture has been taken, the bacilli will be 

 scattered over the field as single bacteria. If the blood is 

 that of hog cholera, the bacilli will be seen to lose their 

 motility, become shortened, rounded, and to stick to each 

 other, forming clumps. They have been agglutinated. The 

 reaction takes place in from five to thirty minutes ; it is al- 

 ways well to wait at least an hour. A negative test shows 

 no clumps, i. e., no agglutination, and the bacteria retain 

 their motility. 



Test-Tube Method: — This method of making the 

 agglutination test has the advantage of not requiriiig a 

 microscope. Let us take the bacillus dysenterije for ex- 

 ample. Obtain a culture of the bacilli in a test-tube of bouil- 

 lon (i8-hour-old culture is best; old culture will do) and 

 also place some blood from the suspected animal in another 

 test-tube. After the blood has clotted, take some of the 

 serum, about 1-50 of the bouillon, and add it to the test- 

 tube containing the given bacilli. If the bouillon measures 



