DESCRIPTIONS OF PATHOGENIC BACTERIA. 169 



and streptococci and, on the other side, the 

 great differences in the susceptibility of man, 

 we can well understand how these widely spread 

 bacteria may produce suppuration of the in- 

 ternal organs or multiple external abscesses in 

 one person, in another angina or catarrh of 

 the mucous membrane, and in still another 

 rheumatic processes. It may be, moreover, 

 that these organisms are etiologically con- 

 cerned in those obscure pathological processes 

 referred to " catching cold "and which we can 

 hardly speak of as specific diseases. Bacteria 

 of this sort which live in or upon sound indi- 

 viduals without harming them may be called 

 u ceco-parasites." If any weakening of the tis- 

 sues be brought about by privation, or any 

 seat of disease be created by sudden injury 

 such as burning or freezing, these ubiquitous 

 bacteria take advantage of such a local pre- 

 disposition to display their pernicious ac- 

 tivity. 



Wherever a predisposition exists on the 

 part of the tissues, we find a number of mi- 

 crobes that can call forth inflammation and 

 suppuration. In inflammations of the valves 

 of the heart there are found under various 

 circumstances, staphylococci, streptococci, or 

 gonococci, and typhoid, pneumonia or tubercle 

 bacteria. The same thing is true in certain 



