GLANDERS GROUP 255 



suspension is prepared by removing the growth from a young 

 culture on agar and suspending it in physiologic salt solution con- 

 taining 0.5 per cent, phenol. This is heated at 70 for two to 

 four hours; this kills the bacteria, but does not interfere with the 

 agglutination reaction. Equal amounts of this suspension are 

 placed in a series of small test-tubes, and to these are added equal 

 amounts of different dilutions of the serum to be tested, and the 

 final dilutions of the serum determined. Dilutions are usually 

 prepared 1: 100, 1: 200, 1: 400, 1: 500, 1: 800, 1: 1000, and up to 

 1 : 8000 or more. The tubes are kept at 37 for from twenty-four 

 to thirty-six hours. A positive reaction is indicated by a film 

 covering the entire bottom of the tube, a negative by no pre- 

 cipitate or a little sediment in the bottom of the convexity, not 

 forming a film. Normal blood frequently gives the reaction in 

 dilutions as high as 1 : 500, and usually in dilutions of 1 : 100 or 

 less. The serum of injected animals will commonly agglutinate in 

 dilutions of 1 : 800, 1 : 1000, and much higher. A positive reaction 

 in dilutions of over 1 : 1000 may be considered diagnostic. Whether 

 or not a positive reaction is accompanied by a complete clearing 

 of the test fluid depends upon the concentration of the suspension 

 and the dilution and potency of the serum used. The fluid may 

 remain somewhat cloudy in a positive reaction in the higher 

 dilutions, not all the organisms being agglutinated. The sus- 

 pensions of killed organisms may be secured ready for use from 

 some pharmaceutical houses, together with tubes and materials for 

 preparing the proper dilutions. The suspension when properly 

 prepared and preserved in the dark will keep for a considerable 

 time. The microscopic test for agglutination has not proved 

 practicable, as normal serum agglutinates microscopically in 

 high dilutions. When properly carried out, the macroscopic 

 test is claimed by some to be an even better diagnostic than 

 mallein. 



Konew's Precipitation Test or the Ring Test. A solution of 

 glanders bacillus prepared by adding 10 c.c. of an 8 per cent, 

 antiformin * solution to the bacilli washed from the surface of a 

 forty-eight-hour slant agar culture. The bacteria will go into 



! The composition of antiformin is given on p. 312. It is a patented 

 disinfecting solution, and may be purchased upon the market. 



