402 ON THE ORIGIN, PROPAGATION, 



air, and have been deposited by it. Considering the 

 number of persons who suffer from phthisis, and the 

 billions of bacilli expectorated by each of them, it 

 would seem a fair a priori deduction that wherever 

 people with their normal proportion of consumptive 

 subjects aggregate, the tubercle bacillus must be pre- 

 sent everywhere. Hence the doctrine of "ubiquity," 

 enunciated and defended by many writers on this ques- 

 tion. Common observation throws doubt upon the 

 doctrine, while the experiments of Cornet are distinctly 

 opposed to it. Tested by the dust deposited on their 

 furniture or rubbed from their walls, the wards of some 

 hospitals were found entirely free from bacilli, while 

 others were found to be richly and fatally endowed with 

 the organism. Cornet, it may be remarked, does not 

 contend that his negative results possess demonstrative 

 force. He is quite ready to admit that, where he failed 

 to find them, bacilli may have escaped him. But he 

 justly remarks that, until we have discovered a bac- 

 terium magnet, capable of drawing every bacillus from 

 its hiding-place, experiment must remain more or less 

 open to this criticism. Cornet's object is a practical 

 one. He has to consider the probability, rather than 

 the remote possibility, of infection. The possibility, 

 even in places where no bacilli show themselves, may 

 be admitted, while the probability is denied. Such 

 places, Cornet contends, are practically free from 

 danger. 



In the differences as to infectiousness here pointed 

 out, we have an illustration of wisely-applied knowledge, 

 care, and control, as contrasted with negligence, or 

 ignorance, on the part of hospital authorities. And 

 this may be a fitting place to refer to a most impressive 

 example of what can be accomplished by resolute su- 

 pervision on the part of hospital doctors and nurses. 



