11 



directed to the stools of typhoid patients as being capable of 

 conveying the disease germs during the first four to six 

 weeks, that is during the active phases of the disease and 

 the early stages of convalescence, the urine not being specially 

 attended to. But since we now know that the patient, 

 weeks after convalescence has set in, voids typhoid bacilli 

 by the urine, the presence in any locality of a convalescent 

 from typhoid fever, in whom the stool has perhaps ceased 

 to be infective, remains, nevertheless, a fruitful source of 

 typhoid bacilli. We may have a seaside place in whose 

 population no typhoid fever cases have occurred, but to 

 which seaside place a person convalescent from typhoid 

 fever has been taken for recuperating ; the sewage of this 

 seaside place ostensibly free from typhoid fever would 

 nevertheless contain plenty of typhoid bacilli which might 

 find access to shellfish laid clown or kept on or near the 

 shore of such a place. 



The typhoid bacillus belongs to a large group of microbes 

 coli-typhoid group which in morphological, cultural and 

 physiological respects possess certain characters in common, 

 but the individual species constituting the group differ, 

 nevertheless, from one another in definite manner. As to 

 the B. typhosus its essential differential character is that it is 

 found, as described above, in definite distribution in typhoid 

 fever and in this disease only, and that its introduction into 

 the alimentary canal under suitable conditions, and its multi- 

 plication within the infected person, sets up the specific 

 disease typhoid fever, as has now amply been demonstrated 

 by indirect epidemio-logical evidence, as also unfortunately 

 in several direct instances amongst those who have worked 

 in the laboratory with cultures of the typhoid bacillus. 

 None of the other species belonging to the coli-typhoid group 

 are connected, as cause, with typhoid fever, although some, 

 like the Bacillus Gaertner, some virulent coli-like organisms, 

 the Bacillus paratyphosus and Bacillus dysenteric, are con- 

 nected with other acute intestinal diseases, but not of the 

 nature of true enteric fever. 



The morphological and cultural characters by which the 



