COMMON BACTERIAL INFECTIONS OF THE DI- 

 GESTIVE TRACT, CONSIDERED FROM THE 

 STANDPOINT OF THE MICROORGANISMS 



THE COLON-TYPHOID-DYSENTERY GROUP 



A SURVEY of the bacteria which we may include in 

 the colon-typhoid-dysentery group is beset with many 

 difficulties with respect to satisfactory classification, 

 arising from an incomplete knowledge of the biological 

 characters of these bacteria. We know enough, however, 

 to see that we are dealing with microorganisms not sep- 

 arated from one another by unbridged gaps, but rather 

 linked in series by most intimate affinities. 



Colon Bacilli. If we ask the question, what patho- 

 logical consequences do the colon bacilli of the human 

 intestine bring to the human species, the answer is 

 by no means simple. Many conditions formerly at- 

 tributed to the colon bacilli were given their position 

 without adequate reason. To-day we have the right to 

 insist on knowing the fermentative and agglutinative 

 as well as the cultural characters of the colon organisms 

 which are stated to be the causes of disease, and too 

 often this information is not given. 



At the present time the view is generally held by 

 pathologists that colon bacilli are capable of doing 

 damage in two ways, as infective agents outside the 



150 



