AGGLUTINOGEN. 



221 



Multiplicity 

 gl n l R8rlutino " 



Aggiutinogen may be extracted from micro- 

 organisms by chemical processes. The presence 

 of the substance in the extracts becomes manifest 

 when immunization with them causes the forma- 

 tion of an agglutinating serum. This, again, is 

 the "test of immunization." 



The agglutinogen of one bacterium is not iden- 

 tical with that of any other. If they were identi- 

 cal, immunization with the one would yield an ag- 

 glutinating serum of equal power for both cells; 

 this, however, is not the result obtained. On the 

 other hand, the agglutinins of two different organ- 

 isms may coincide to a certain degree, as will be 

 shown under the subject of "group agglutination." 

 Certain experiments go to show that the agglutin- 

 ogen of even a single micro-organism is not uni- 

 form substance. One portion is heat-susceptible, 

 being destroyed at 62 C., while another portion is 

 said to resist a temperature of 165 C. Such tech- 

 nical questions continue to be investigated. 



Agglutinogens are said to pass through semi- Fiageiiar 

 permeable membranes, while agglutinins do not. 



Smith and Eeagh distinguish two kinds of ag- 

 glutinogen in those bacteria which possess flagella, 

 one peculiar to the cell body, and the other to the 

 flagellae. 



Agglutinin may be precipitated completely from 

 a serum by the sulphates of magnesium or ammo- 

 nium, when the salts are used in proper concentra- 

 tions. Because of their reaction to such precipi- 

 tating agents, agglutinins are thought to belong to 

 the globulin fraction of serums ; whether globulins 

 or not, they are precipitated with them. 



Agglutinins resist digestion with pepsin and 

 papayotin, but are destroyed after prolonged ex- 



and 



properties of 

 Assln 



