100 VARIATIONS IN PATHOGENICITY [CH. vn 



to epidemics of "influenza" characterised by symptoms 

 resembling in one epidemic a simple coryza, in another 

 rheumatic fever, in a third typhoid fever, and in a fourth 

 cerebrospinal meningitis. 



5. In the fifth place, the train of symptoms characteristic 

 of infection by one organism may develop as a result of 

 infection by a totally different organism. 



A striking instance of this is recorded by Head and 

 Wilson (1899) who proved that a supposed case of rabies was 

 actually due to infection by the diphtheria bacillus. The 

 diagnosis of rabies was founded on the history and clinical 

 symptoms. " The well authenticated history of a bite on the 

 cheek by an unknown animal, the two months' incubation 

 period, the onset with extreme pain and numbness in the 

 region of the scar, the development of the characteristic 

 laryngeal and respiratory spasms on attempting to take 

 liquids, the spasm at first being slight but later more pro- 

 nounced and towards the close again feeble or absent, the 

 insomnia, the absence in the beginning of fever which later 

 in the illness became pronounced, the rapid pulse at all 

 stages, the attacks of violent delirium interspersed with 

 periods of calm and complete rationality, the absence of all 

 symptoms pointing towards any other simulating disease and 

 the fatal termination all serve to make an almost complete 

 picture of rabies." The Klebs-Loeffler bacillus was isolated 

 from the ventricular fluid and detected in the nerve cells of 

 the medulla. The recognition of this organism was complete 

 and beyond doubt. " Not less suggestive of rabies than the 

 clinical history were the results of subdural inoculations of 

 rabbits with emulsions prepared from the medulla of the 

 patient. There occurred the long period of incubation (20 

 and 21 days) followed by phenomena similar to those in 

 experimental rabies of rabbits, and other rabbits inoculated 

 subdurally with the medulla of the first rabbits behaved in 

 a similar manner." B. diphtheriae was demonstrated after 

 death in the medulla of the rabbits. By a thorough investiga- 

 tion, full details of which are given, infection by the virus of 

 rabies was definitely excluded. 



