THE DIAGNOSIS OF GLANDERS 123 
evinced by the fact that the layer is less dense in the higher 
dilutions. The reaction may begin in 6 hours, but cannot be 
considered complete until from 24 to 72 hours have elapsed. 
Often, however, a reaction appears in less than 24 hours. 
After the agglutination is completed, further standing pro- 
duces no visible change in the test fluid. 
A negative result shows a small round concentrated spot of 
sediment in the center of the convexity at the bottom of the 
tube, the test fluid remaining apparently unchanged even after 
several weeks. 
An agglutination in a dilution of 1 to 500 is considered 
suspicious. 
An agglutination in a dilution of 1 to 800 is very suspicious. 
An agglutination in a dilution of 1 to 1000 is considered a 
positive reaction. 
Complement-fixation method. This method is one that re- 
quires considerable special equipment and material, such as 
a powerful centrifuge, immunized rabbits and sheep for cor- 
puscles. The method is considered to be very accurate. 
Those who wish to use it are referred to Bulletin No. 136, 
Bureau of Animal Industry, and to Moore’s Principles of 
Microbiology for technique. ‘ 
If laboratory aid is required the blood for the serum tests 
should be drawn aseptically in sterile bottles. About 20 cc. of 
blood is sufficient. Securely pack and send. In case of organs 
the parts containing the lesions should be sent. 
