44 FREDERICK EBERSOX 



in the absorption test. The serum, after complete absorption with the 

 coccus, showed a reduction in agglutinating titer, stopping at 1-1600, 

 whereas the nonabsorbed serum was positive at 1-2000. This removal 

 of agglutinins might suggest antigenic similarity on the part of the 

 coccus for the bacillus. The important point to be noted here, how- 

 ever, is the cumulative action of multiple doses of bacillary diphtheroids 

 containing cocci in mixture. Repeated injections of mass cultures 

 have resulted in the formation of agglutinins specific for each type of 

 organism, and the slight reduction in titer is thereby accounted for. As 

 a further corollary, Strain 28 absorbs most of the agglutinins out of 

 the bacillary serum, showing that the organisms are antigenically the 

 same. That the absorption is not more complete may be due to the 

 fact that but one exposure was made with the organism in question, 

 whereas in the case of the coccus strain the serum was doubly absorbed. 

 From these findings the conclusion may be drawn that the bacillus is 

 antigenically distinct from the coccus. 



Two possibilties are suggested in explanation of the presence side 

 by side of two biotypes; one is that of mutation and the second a 

 symbiotic relationship of a contaminating coccus and a typical bacillary 

 diphtheroid. The possibility of mutation is not far-fetched, although 

 highly improbable in this instance. As to a symbiosis, the likelihood 

 is less remote. In either case the question can be answered categorically 

 by applying the single bacterial-cell method to the conditions which 

 prevailed in the experiments given here. These experiments will be 

 described in a future paper. 



SUMMARY AND CONCLUSIONS 



The diphtheroids have been studied with regard to nomenclature 

 and revised according to accepted standards for the naming of valid 

 species. 



A tentative classification is offered with a view toward grouping 

 prominent biologic characters. Nine distinct groups of diphtheroids 

 are outlined with a type species for each group and corresponding 

 subspecies. 



It is evident that the groups hitherto accepted as types for all diph- 

 theroids are insufficient and not representative of a broad classification. 



Diphtheroids isolated from glands and tissues 21 different sources 

 fall into 12 distinct fermentative groups. The greatest number of 

 organisms are nonfermenters. Strains isolated from the eve and nose 



