346 DIPHTHERIA. 



bacillus were similar to those of Loffler. Since that time 

 the organism has been the subject of much research and 

 discussion. Roux and Yersin, on the other side, have 

 found that this bacillus corresponds in all its characters 

 with a greatly attenuated diphtheria bacillus, and conclude 

 that it is really of the same nature. They failed to make 

 it virulent by any method ; but this result was also obtained 

 in the case of greatly attenuated diphtheria bacilli. There 

 can be no doubt that a number of different organisms have 

 been described under this name, some of which can be 

 distinguished by their cultural and microscopical characters. 

 In some cases the colonies are whiter, and more shining on 

 the surface ; in others the growth in broth never produces 

 an acid reaction, and is more abundant and flocculent ; 

 and others, again, have not the same microscopical appear- 

 ance in young cultures as the diphtheria bacillus. On the 

 other hand, it is well established that there can be not in- 

 frequently cultivated from the throat in various conditions an 

 organism which has all the characters of a diphtheria bacillus, 

 with the single exception that it is not virulent to animals, 

 and does not produce toxine. Biggs has found that there 

 are two varieties of pseudo-diphtheria bacillus, one of which 

 produces an acid reaction in broth containing glucose, whilst 

 the other does not. According to his statistics the two 

 varieties appear to occur with about the same frequency, 

 and these observations have been in the main confirmed 

 by Cobbett and Phillips. It is rare, however, that these 

 pseudo - diphtheria bacilli occur in large numbers in the 

 throat as found by microscopical examination and by 

 cultures, and it is not often that difficulties in diagnosis 

 arise. In some cases, however, such difficulty may be met 

 with ; and in the first place, all the cultural characters must be 

 carefully examined, including the reaction produced in broth. 

 By this procedure it may be determined whether a parti- 

 cular organism differs in certain points from the diphtheria 

 organism. In cases where it corresponds in all these 

 characters, distinction, if such exists, can be obtained by 

 means of inoculations only. But we consider that for all 



