QUESTIONS AND ANSWERS 167 



a greater amount, will cause the clumping, or agglutinating of 

 glanders bacilli in suspensions of potato or agar cultures, whereupon 

 these clumps are precipitated to the bottom of the supernatant clear 

 fluid. 



The precipitin test is based upon the fact that the serum from 

 a glandered horse produces a flaky precipitate in the filtrate of 

 glanders cultures, when mixed together. 



In a test for glanders, state the relative advantages of the mallein and 

 agglutination tests. 

 The mallein test can only be used on living animals. The agglu- 

 tination test can be applied to dead animals. The former method 

 is long and tedious and cannot be used when fever is present, 

 whereas the latter is simple for the practitioner, most of the work 

 being done in a laboratory ; presence of fever is no hindrance. Mal- 

 lein is more accurate; agglutination does occur with the serum of 

 healthy animals and the line of distinction is often close. The mal- 

 lein test necessitates the confinement of the patient, whereas the 

 agglutination test allows the horse to continue at work. 



Describe the course to be pursued in testing with mallein. 



Take three preliminary temperatures, at least four hours apart. 

 With antiseptic precautions, inject the mallein subcutaneously. 

 Eight hours later, make a temperature reading and thereafter every 

 two hours until twenty hours after injection. A reaction consists 

 of a gradual rise and fall of temperature of at least 2° P., and a 

 local reaction shown by an cedematous, painful swelling at the seat 

 of injection, lasting four or five days. Healthy horses are not 

 affected except, perhaps, by a local swelling which disappears in 

 twenty-four hours. 



The ophthalmic mallein test depends upon a purulent conjunc- 

 tivitis following from 4 to 24 hours after the instillation of a few 

 drops of a concentrated mallein solution into the conjunctival sac. 



The cutaneous mallein test depends upon a local reaction follow- 

 ing an intradermal or endermic inoculation with mallein. 



Describe the complement fixation test for glanders. 



The phenomenon of haemolysis is the fundamental principle of 

 this test. If the blood-serum of a rabbit is treated with the red 

 blood-corpuscles of a sheep, antibodies (hcemolytic amboceptors) 

 will be formed. These antibodies have the power to dissolve sheep 

 red blood-corpuscles in the presence of free complement. This 

 process is called hcemolysis and depends upon two substances; one 

 of these, the complement, is present in the blood of every animal 



