178 APPLIED BACTEBIOLOGY 



irritation as to render it possible for the bacillus (from some 

 other source) to gain headway. 



During epidemics the greatest incidence of attack is 

 always heaviest upon houses or districts in which drainage 

 defects exist. These facts should always be taken into 

 consideration in connection with outbreaks of enteric fever. 



It is still open to question how far we are compelled to 

 acknowledge the absolute ' specificity ' of the Eberth-Gaffky 

 bacillus, and whether we cannot conceive of varying degrees 

 of ' specificity.' It seems not impossible that the pseudo- 

 typhoid bacilli may be the true Eberth-Gaffky in transition 

 stages. If we determine that enteric fever can be caused 

 by the Eberth-Gaffky bacillus alone, and refuse to admit 

 the possibility of varying degrees of ' specificity ' we shall 

 have great difficulty in assigning the cause of those cases of 

 typhoid fever which present all the characteristics of true 

 typhoid, in which no possible connection with any previous 

 case can be traced, and where we have, to all appearances, 

 true typhoid arising de novo. 



To clear up these very interesting and important points, 

 detailed information must be collected respecting cases in 

 which no connection with previous cases can be traced, and 

 further experimental work is needed with respect to the 

 organisms above referred to as pseudo-typhoid bacilli, par- 

 ticularly as to their effects on animals. 



The Bacteriological Diagnosis of Typhoid Fever. 



The Serum Diagnosis of Typhoid. — This new addition to our 

 diagnostic resources depends on the fact that the serum of 

 an individual immunised against the typhoid bacillus exerts 

 a clumping or agglomerating action on actively motile 

 typhoid bacilli, when suspended in a suitable medium. 

 The reaction was discovered independently by Widal and 

 Griinbaum, and the idea of applying the reaction for the 



