PATHOGENIC MICHOBES— INFECTION 113 



go on to cite a series of facts which have modified the idea of 

 rigorous specificity among microbes, a specificity which in the 

 early days of medical bacteriology was believed to be 

 absolute ; or at least these facts have restricted this idea (by 

 compelling us to create new varieties), although we may still 

 regard it as sufficient for the purposes of medicine and hygiene. 



It was long the custom to talk simply of the bacillus of 

 diphtheria, the typhoid bacillus, the B. of dysentery, the 

 meningococcus, the cholera vibrio, etc., but little by little 

 there have been discovered bacteria, close relatives of each of 

 these typical microbes, but not possessing all their characters. 



From the time of the first bacteriological discoveries in 

 diphtheria, bacilli were isolated from the mouth exactly 

 similar to the pathogenic bacillus, but non-toxic ; the best 

 known is that described under the name of Hoffmann's 

 bacillus. They have been called pseudo-diphtheria bacilli, and 

 have been found in diphtheritic sore throat, in scarlatinous sore 

 throat, and in the normal conjunctiva, even sometimes in 

 vaccine lymphs. Some of them are pathogenic for the guinea 

 pig, and produce in it a septicEemia bearing no resemblance to 

 diphtheria. They are not affected by antidiphtheritic serum 

 and are incapable themselves of being used to produce such 

 a serum. Roux's opinion was that it was a question of 

 degenerated diphtheria bacilli, or of bacilli not yet adapted, 

 not having yet found the conditions capable of exalting their 

 virulence. It must be added that the name of pseudo- 

 diphtheria has been incorrectly applied to bacilli which do 

 not deserve the name, even by their form. 



It is no use playing with words. It is on the clinical facts 

 the problem ought to depend. There are found in the most 

 typical cases of diphtheritic sore throat diphtheria bacilli 

 possessing every degree of toxicity, and also bacilli which are 

 not pathogenic {i.e., for the guinea-pig, since they cannot be 

 inoculated in man). All these bacilli are called diphtheria 

 bacilli. On the other hand, there exist non-diphtheritic 

 affections both of the throat and of the nose in healthy 

 individuals where bacilli resembling diphtheria but non-toxic 



