270 THE AMERICAN MONTHLY [Sept 



it may be, must be located somewhere on the premises, 

 harboring and perpetuating the infection so that when 

 destroyed within the body of every inmate, reinfection 

 from without becomes possible again. The growth of the 

 bacillus in media external to the body might very well or- 

 iginate atypical forms. But be this as it may, the writer 

 as health officer and practising physician, has repeatedly 

 been brought face to face with this very question as to the 

 life of the diphtheria bacillus outside the body. As a 

 rule when the disease has given evidence of a tendency 

 to recur in a particular house or neighberhood it has been 

 possible to find somewhere about the premises an accum- 

 ulation of material obviously adapted to serve as a cul- 

 ture medium for this particular bacillus, and so situated 

 that effluvia from it would surely gain access to those 

 very persons who contracted the disease. 



In any such case it is, as a rule, difficult to secure pure 

 cultures of any particular bacillus that may be in ques- 

 tion. The varieties present are more numerous than in 

 the cultures from the throat so that the one wanted is 

 lost in the crowd, and there may be admixture of much 

 extraneous matter, if direct inoculation of the culture 

 medium is attempted, so that it is difficult to get conclu- 

 sive evidence. Thus far the best evidence attainable has 

 been the immediate and complete disappearance of the 

 disease, when the proper source of the trouble has been 

 identified, and effectual measures for its removal by dis- 

 infection, or otherwise, have been adopted. 



Still it is possible that definite information in regard 

 to the life of the bacillus outside the body may' be had 

 experimentally. It should be determined for what length 

 of time the bacillus remains alive not only in a single 

 culture, but also in a succession of cultures, transferred 

 from one to another. This may be done with the vari- 

 ous mtMlia ordinarily employed for such purposes,or with 

 saliva, or pus, or mucu8,or other secretions from the body, 



