BACTERIA AND DISEASE 289 



Diphtheria (Klebs-Loffler Bacillus, 1882-1884). Diph- 

 theria is an infective disease characterised by a variety of 

 clinical symptoms, but commonly by a severe inflammation 

 followed by a fibrous infiltration (constituting a membrane) 

 of certain parts. The membrane ultimately breaks down. 



BACILLUS OF DIPHTHERIA 



losis and hygiene, to an enormous advance in sanitation, and to more efficient 

 land drainage. 



7. Not all persons are equally liable to consumption, some being much more 

 susceptible than others. We have mentioned the predisposing influence of 

 certain trades. There is also heredity, which acts, as we have said, in trans- 

 mitting a tubercular tendency, not commonly the actual virus of the disease ; 

 there is, thirdly, the debilitating effect of previous illness or chronic alcohol- 

 ism ; there is, fourthly, the habitual breathing of rebreathed air ; and, fifthly, 

 there are the conditions of the environment, like dampness and darkness of the 

 dwelling. Such influences as these weaken the resisting power of the tissues, 

 and thus afford a suitable nidus for the bacillus conveyed in milk or by the 

 inspiration of infected dust. 



8. Consumption is curable if taken in time. In cases where the lungs are 

 half gone, and consist of large cavities, it is obvious that curability is out of 

 the question. But if the disease can be properly treated in its earliest stages, 

 there is considerable likelihood of recovery. 



9. The breath is not dangerous, as far as we know, but there is danger from 

 discharges of any kind from any infected part, whether lungs or bowels ; for 

 such discharges, when dry, may readily pollute the air, and either the bacilli 

 or spores be inhaled into the lungs. 



10. The chief channels of personal infection or the spread of the disease 

 amongst a community are two : (a) dried tubercular sputum (or other tubercu- 

 lar discharges) ; (b) infected milk or meat. So long as the former remains wet 



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