110 INFECTIONS OF THE DIGESTIVE TRACT 



agglutinative characters of certain intestinal bacteria 

 such as typhoid and dysentery organisms with human 

 or experimentally induced sera possess a high degree of 

 specificity. There was also at first an inclination to 

 believe that two bacteria of different origin possessing 

 the same agglutinative characters with one serum were 

 brought very close together by virtue of this fact. It is 

 now clear that the failure to distinguish between group 

 or common agglutinins and specific agglutinins may lead 

 one to think bacteria are identical when this is really not 

 so. The group agglutinins may to a considerable extent 

 be removed by the procedure of absorption which has 

 lately come into use. By means of absorption methods 

 it becomes possible to largely remove the common 

 agglutinins from a serum which contains them by bring- 

 ing this serum into contact with bouillon cultures of the 

 bacteria in question and after a certain period of contact 

 filtering off the bacteria, which have absorbed from the 

 serum a large part of the common agglutinins. The 

 specific agglutinative properties of the serum now come 

 very clearly into play and may be a great aid in deter- 

 mining the relationship of two microorganisms suspected 

 of standing in close' relation to each other. The value 

 of this absorption test is somewhat in question in some 

 laboratories, but it has given a high degree of satisfaction 

 in the laboratory of the Board of Health in New York 

 City, where it has been employed extensively and sys- 

 tematically by Dr. Park and Dr. Collins. 1 



1 The absorption method has also been successfully employed 

 by Dr. E. K. Dunham in his careful study of the agglutinins of the 

 meningococcus. 



