OH. VII] TARIATIONS IN PATHOGENICITY 101 



Dunn and Gordon (1905, vide svpra p. 99) have described 

 almost typical cases of scarlet fever, of cerebrospinal 

 fever and of influenza, which proved to be due to infec- 

 tion by the micrococcus catarrhalis. Gordon has described 

 elsewhere typical oases of cerebrospinal fever due to B. 

 typhosibs. 



Nash has recorded a remarkable case of malignant en- 

 docarditis characterised by fever, constipation, headache, 

 drowsiness and delirium, photophobia, strabismus, head re- 

 traction and the appearance of a petechial rash. The illness, 

 in fact, presented all the clinical features of cerebrospinal 

 fever. A copious growth of a pure culture of the Klebs- 

 Loeffler bacillus was obtained post mortem from the spinal 

 fluid and a similar growth from the heart's blood. There was 

 a history of a discharge from the ear at the beginning of the 

 illness but no history of sore throat. 



Thomson (1911) has recorded his own experience of an 

 acute inflammation of the throat simulating diphtheria in 

 producing, in the fourth week of the illness, temporary para- 

 lysis of the tongue, arms and legs, but proved to be due to 

 pneumococcal infection. 



Colman and Hastings (1909) state their conviction that 

 some strains of B. coli are capable of causing a disease clini- 

 cally identical with typhoid fever. 



III. The pathogenicity of bacteria presents yet another 

 aspect, namely the character of the lesions produced by them 

 in the living tissues. 



This can be studied in two ways. Firstly, by observing the 

 lesions produced in the body at various stages in the course 

 of an infective disease ; and secondly, by observing the lesions 

 produced by the artiflcial inoculation of organisms into 

 animals, both at the site of inoculation and elsewhere. 



1. The lesions produced in the course of disease and ob- 

 served post mortem not infrequently enable one to identify 

 the infecting organism. For example, tuberculous ulceration 

 of the intestine, tuberculous consolidation of the lungs, and 

 tuberculous invasion of the skin, present altogether diflerent 

 features from typhoid ulceration of the intestine, pneumococcal 



