THE AGGLUTINATION TEST; WITH PARTICULAR 



REFERENCE TO ITS USE IN THE CONTROL OF 



CONTAGIOUS ABORTION IN CATTLE. 



By Eric ]\Iaxwell Robinson, M.R.CA'.S. 



To the student of general biology there are few subjects 

 which are of more interest than the properties of the blood- 

 serum of an animal, including the reactions to invasions of 

 foreign elements, such as bacteria, protozoa and albuminous 

 substances of various kinds. It is with one class of antibodies 

 produced as a result of the invasion of the animal body by 

 bacteria that I wish to deal in this paper, namely, the agglutinin^ 

 or substances which cause clumping of the invading organisms. 

 For the detection of the presence of agglutunins in the serum 

 of an animal, a test has been devised which is called the agglu- 

 tination test or Grunbaum-Widal reaction. The agglutinins 

 and aggliuination will first be described, after which the actual 

 technique of the test will be given and its application discussed 

 in connection with the control of such a disease as contagious 

 abortion in a herd of cattle. 



The presence in blood-serum of substance which could 

 cause the agglutination or clumping together in masses of 

 organisms was first noticed by (iruber and Durham in 1896, 

 during some experiments with antiserum against the cholera 

 organism. These workers found that the serum produced by 

 immunising an animal against cholera had the power of agglu- 

 tinating cholera organisms. In their experiments they added 

 cholera antiserum to a broth culture of cholera organisms, with 

 the result that the organisms formed small visible clumps in the 

 fluid, which fell to the bottom of the test-tube, leaving the ])re- 

 viously turbid Ijroth perfectly clear. This agglutination wa.s 

 found to occur with other organisms and their antisera, and it 

 was then recognised that agglutinins were produced l)y most 

 kinds of bacteria. 



The process of agglutination can he watched in a test-tul)e 

 containing a faintly turbid emulsion of an organi.-^m and its 

 antiserum. The process takes place most rapidly at the tempera- 

 ture of the animal body, i.e.. 37° C. or thereabouts, so that the 

 test-tulie has to be incubated. If one closelv observes the 

 turbid fluid, one first notices that it is becoming finely granular, 

 which is best seen by comparing with a control tube containing 

 only bacteria without any antiserum. These fine granules will 

 be seen to be moving, some rising, others falling, but eventually 

 larger granules form, and then finallv small masses of bacteria, 

 which fall to the bottom of the test-tube, and the fluid is left 

 (juite transparent and clear as water. An ordinary suspension 

 of organisms remains turbid for a long time, and never leaves 

 a clear fluid over the deposit at the bottom of the test-tube. 

 Complete agglutination usually takes about a day. but the length 



