AGGLUTININSAGGLUTINOIDS AND PROAGGLUTINOIDS 145 



cultures of spleen tissue in vitro will form specific agglutinins for 

 typhoid bacilli if the virus is brought into contact with the tissue 

 cells. As a general rule the concentration of a specific agglutinin is 

 greater in the blood stream than in the tissues of the body. 



Preparation of Specific Agglutinating Sera. Specific agglutinating 

 sera for experimental purposes are best obtained from rabbits, whose 

 serum normally contains no agglutinin. Several, usually three to 

 five intravenous injections of 1, 2, 3 and 5 loopfuls respectively of 

 killed cultures of typhoid bacilli at eight-day intervals, produce pow- 

 erful agglutinating sera. The animal is bled about two weeks after 

 the last injection. For large amounts of agglutinating sera horses or 

 asses must be used. 



Properties of Agglutinins. Agglutinins are of unknown chemical 

 composition, but they may be separated from solution by those pre- 

 cipitants which throw down globulins, and they may be removed 

 from solution by absorption in animal charcoal. Toward heat they 

 are moderately resistant, usually remaining active after an exposure 

 of twenty minutes to 55 C., a degree of heat sufficient to inactivate 

 complement. Agglutinins, therefore, appear to be quite distinct 

 from bacteriolysins. The temperature at which agglutinins are de- 

 stroyed depends upon their specificity, agglutinins for plague bacilli 

 being more sensitive than typhoid agglutinins. The reaction of the 

 medium also affects their stability. Alkalis, even in dilute solution, 

 rapidly destroy agglutinins; acids are somewhat less harmful. Nat- 

 urally the duration of exposure to these various agents exercises an 

 important influence upon their resistance. Agglutinins do not appear 

 to pass through parchment membranes, but it is stated that agglu- 

 tinogen will slowly diffuse under similar conditions. This would sug- 

 gest that the agglutinin molecule is larger than the agglutinogen 

 molecule. Preserved in a dry state, in a cool place away from light, 

 agglutinins preserve their properties unimpaired for days. In 

 solution and upon standing agglutinins rapidly lose their property 

 of clumping bacteria, but they still retain their original ability to unite 

 firmly with bacteria. Ehrlich designates agglutinins which have 

 lost their ability to cause clumping but still retain their combining 

 power for agglutinogen, agglutinoids. In his terminology they are 

 side-chains of the second order which have lost their agglutinophore 

 (ergophore) group. Agglutinins acting in neutral salt-free media 

 also fail to cause clumping of bacteria, but in this case the addition 

 of a small amount of NaCl or even some weak acid very soon brings 

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