2 MICRO-ORGANISMS AND DISEASE [intro. 



bearing on their production in particular individuals specially 

 predisposed. 



To mention two series only : it has been shown that there 

 occur in some individuals a variety of localised inflam- 

 matory and suppurative foci, which are intimately associated 

 not necessarily with pus-forming cocci — the microbes of typi- 

 cal suppuration — but with one or the other kind of microbes 

 — e.g. proteus vulgaris, bacillus coli, pneumococcus, and other 

 microbes. These organisms have in these particular cases 

 only caused disease ; under healthy conditions their presence 

 in the various tissues is insufficient to do so. Or, to take 

 another series of disorders : fatal summer diarrhoeas in 

 children and in adults. Bacillus coli or proteus vulgaris 

 are under ordinary normal conditions found in the intestine, 

 in the large intestine and in the lower ileum, as also in 

 many other conditions associated with putrid proteid 

 decomposition. Under certain abnormal conditions of the 

 intestine caused, in the first instance, by fermentative 

 changes, such as the lactic or acetic fermentation or others, 

 the intestinal tract, specially the small intestine, is rendered 

 highly favourable for the multiplication of those microbes, 

 so that it practically contains a pure culture of them. 

 Bacillus coli and proteus vulgaris, being both endowed 

 with the power of intensive proteid decomposition, would 

 under these favourable conditions of multiplication produce 

 copiously poisonous alkaloids, ptomaines or allied toxins, 

 which, absorbed into the circulation, might produce fatal 

 results. 



In order to pass in review all the ascertained facts and 

 observations in this vast and constantly growing field of 

 pathology, and to appreciate and to assign their true value 

 to the many observations bearing on this relation of micro- 

 organisms to disease, it is necessary that the reader, and still 



