320 DE NOVO OEIGIN OF BACTERIA 



certainty, give rise to one and the same'Contagious affection which- 

 ever may be the site of their introduction. 



These are all facts the importance of which can scarcely be 

 over-estimated. They afford a sort of beacon light capable of 

 illuminating the obscurity surrounding the origin of many other 

 contagious diseases. A few examples will suffice to show the 

 mode in which they may prove helpful in overcoming difficulties 

 which are commonly thought to stand in the way of a belief in 

 the de novo origin of other of these contagious diseases. 



In Typhoid Fever we have one of the commonest of contagious 

 affections about the possibility of whose de novo origin the greatest 

 difference of opinion has long existed, though of late the ultra- 

 contagionist view has been decidedly gaining ground here as in 

 other directions. But there are, perhaps, some still who, while 

 admitting contagion and the common spread of the disease through 

 contaminated water or milk, or by other agencies, would be 

 inclined to agree with Rodet and Roux that this disease may 

 originate de novo, and that the typhoid Bacillus of Eberth is 

 merely an altered and virulent form of the common Bacillus of 

 the colon. ^ The researches of these observers have tended to 

 show that this latter Bacillus, which commonly exists in the human 

 intestine without harmful results, can become highly virulent and 

 infective, under certain conditions, when introduced into water. 

 Hence they conclude that not only typhoid dejections but simple 

 fascal pollution of water may produce typhoid fever in those who 

 drink it. This is undoubtedly a very important point and one 

 which hitherto has not been adequately taken into account by 

 those who have attempted, as they thought, to trace the source of 

 contagion in many cases of typhoid fever. Because there has been 

 pollution of a water source by a man suffering from diarrhcsa, and 

 typhoid has been produced in persons drinking such water, it must 

 not be assumed without proof that the man who polluted the water 

 was suffering from typhoid fever. As bearing upon this view of 

 Rodet and Roux it is interesting to note that typical enteric 

 lesions in the small intestine have been artiiicially induced in 

 lower animals by R. Row = of Bombay by intoxicating them with 

 the products of the Bacillus coU communis ; and that the lesions 



' As to the degree of the relationship between these forms and the frequent 

 difficulty in distinguishing one from tlie other, see Croolcshank's " Bacteriology 

 and Infective Diseases," Fourth Edition, 1896, pp. 344-46. 



^ "Transactions of the Bombay Medical and Physical Society," vol. iv., No. 5. 



