BACILLUS DIPHTHERLE. 281 



present means, and perhaps require entirely new methods 



for their recognition. Expert microscopists, such as 



Eberth, Weigert, Heuhner, Fiirhringer, Loeffler, have 



been unable to find any micro-organisms, either in the 



deeper parts of the affected portion of the throat, in 



sections of the uvula and tonsils, in the internal organs 



in cases where there has been marked general infection 



of the body (especially in the kidneys), or in the blood. 



When we take into account the great number of negative Negative re- 



results, we must conclude that in the few cases in which examination 



bacteria have been demonstrated in the kidneys, or in of the internal 



organs . 

 other organs, we have to do with bacteria which have 



entered accidentally. Unless we conclude from these 

 negative results that we have not as yet been able to 

 render the infective agents of diphtheria visible, there 

 remains as a second explanation of the facts, the 

 assumption that in the case of diphtheria, even in the 

 cases where the morbid process is spread over parts of 

 the body far removed from each other, we have only a 

 local development of the infective micro-organisms in 

 the diphtheritic membrane, that some soluble noxious 

 materials are produced in that situation by certain 

 micro-organisms, and that these products cause the 

 other symptoms of disease. Even on this assumption, 

 however, we meet with great difficulties in our attempts 

 to discover the specific bacteria which furnish these 

 noxious products. At the primary seat of disease, 

 and in diphtheritic membranes, there is, it is true, no 

 want of micro-organisms ; but since we have begun not 

 to see the cause of the disease in the presence of any 

 sort of bacteria, but to require that for each well- 

 characterised disease there must also be specific, well- 

 characterised infective agents, we have the further task 

 of discovering which of these various species of bacteria 

 is of importance etiologically. We know now that a Mixture of 

 number not only of saprophytic bacteria, but also 





organisms which are very pathogenic in certain animals, the diphther- 

 inhabit the cavity of the mouth of healthy individuals, 

 and these find a good nutrient soil in the diphtheritic 

 membrane ; without doubt, also, one of these kinds may 



