MASS. EXPERIMENT STATION BULLETIN 163. 



The Agglutination Test. 



While the macroscopic agglutination test is of service in the location of 

 bacillary wliite diarrhea infection, its greatest importance lies in the part 

 it plays in the eradication of this disease by detecting in a breeding flock 

 adult birds which are acting as carriers of the organism Bacterium pullorum. 



In spite of the fact that a detailed account of this test for the detection 

 of adult birds which are harboring or have harbored Bacterium -pullorum 

 infection has been presented in an earher bulletin (Gage, Geo. Edward: 

 Bulletin No. 148, 1914, Massachusetts Agricultural Experiment Station. 

 "On the Diagnosis of Infection with Bacterium pullorum in the Domestic 

 Fowl"), we wish to review briefly the important points of the method, 

 especially in relation to the work carried on during the last few months. 



As the reader of our earlier bulletin will remember, the two important 

 biological factors necessary for making the macroscopic agglutination 

 test are (1) a test fluid containing a suspension of the organism causing 

 the disease Bacterium pullorum, and (2) a sample of blood serum from the 

 individual to be tested, and the test is based on the fact that the blood 

 sera of infected and non-infected birds when mixed with the test fluid 

 react differently. The serum of the former, because of the presence of an 

 agglutinin, a substance formed in the body of the bird because of infection 

 with Bacterium pullorum, is capable of producing, when brought in con- 

 tact with a suspension of the organism, a clumping together of the bacteria, 

 a phenomenon which blood from non-infected birds does not show. 



Test Fluid. 



As earlier experiments have shown that a polyvalent test fluid is better 

 suited for laboratory routine than a monovalent one (Bulletin No. 148, 

 pp. 15, 16), we selected for our work the following strains of Bacterium 

 pullorum,: — 



Strain 1. — Isolated March, 1914, from chick received from central 

 Massachusetts. 



Strain 2. — Isolated summer of 1913 from chick inoculated experi- 

 mentally with Bacterium pullor^im isolated from egg from eastern Massa- 

 chusetts. 



Strain 4. — Isolated from chick from eastern Massachusetts. 



Strain 5. — Original strain of Bacterium pullorum, isolated 1911 from 

 chick in Maryland. 



Strain 6. — Isolated spring of 1914 from Massachusetts material sent 

 to laboratory. 



These gave us representative cultures from several localities, and all 

 test fluids have been mixtures of four or all these strains. 



These cultures were studied to make sure of their purity, grown in large 

 quantities on agar-agar at a temperature of 38° C, and the growth washed 

 off in a carbolated sodium chloride solution (0.85 per cent. NaCl solution, 



