8 FREDERICK EBERSON 



work done in this group reveals the fact that there are bacteria which 

 resemble the true diphtheria organism morphologically and culturally, 

 but which differ in one important respect, namely, that of virulence as 

 tested on guinea-pigs. The true Klebs-Loeffler has been shown to fer- 

 ment dextrose, maltose and dextrin with acid production and to possess 

 definite toxic properties on injection, resulting in the death of the 

 animal in 3-4 days with a characteristic inflammation and congestion 

 of the suprarenal glands. To those bacteria which lack this virulence 

 but which otherwise conform to the character of true diphtheria bac- 

 teria, should be assigned the species designation "pseudodiphtheria." 

 The generic name given to the group by Lehmann and ^eumann is 

 Corynebacterium and should be retained for the organisms of this 

 group. Certain characters ought to be accepted as properly belonging 

 to the species before we can adequately define what we mean by a diph- 

 theroid. These may be enumerated as follows : Morphological resem- 

 blance to diphtheria organism, gram-positive, nonmotile, absence of 

 spores, presence or absence of metachromatic granules, no gas-produc- 

 tion in carbohydrate mediums. The fermentation of sugars may or 

 may not occur. This property gives us a basis for classification which 

 will be taken up later. A careful study of the different species which 

 have been described shows that the characters enumerated ought rightly 

 to be accepted as a basis for differentiating the diphtheroids from other 

 bacteria which have been improperly classed with them. With this end 

 in view the different species are taken up individually and examined 

 from the standpoint of validity and priority. The suitability of the 

 name is considered from the viewpoint of sufficient description, and in 

 the light of more comprehensive studies which have given us sugges- 

 tions for proper nomenclature. When the species name implies etiology 

 which is unknown, doubtful or unconfirmed, that part of it is modified 

 to suit the case. 



HISTORICAL REVIEW OF DIPHTHEROIDS AND EMENDATIONS 



B. pseudodiphtheriticum (Loeffler) Migula 



The description is given as follows : Gram-positive, no polar bodies, non- 

 motile. Grows luxuriantly on blood serum with a glistening layer. In broth 

 clouding is produced. Loeffler described a pseudodiphtheria organism in his 

 first paper on the etiology of diphtheria. He said the organism resembled 

 diphtheria but was avirulent for guinea-pigs ; that it was smaller than the true 

 diphtheria and showed a marked absence of club-shaped forms. In .1888. 

 v. Hofmann published an account of avirulent diphtheria-like organisms iso- 

 lated from the oral cavity in 26 of 45 normal persons. He called these organ- 

 isms pseudodiphtheria bacilli and described them as follows : Clouding pro- 

 duced in broth, no acid production, grow at room temperature, no spores. 



