xiv SYNOPSIS 



S. scarlatinae causes scarlet fever iu some cases and pueiperal fever in 

 others. M. catarrhcdis produces symptoms of many diseases— common cold, 

 influenza, scarlet fever, diphtheria, typhoid fever, cerebro-spinal fever. ' 



(4) In different epidemics different types of disease presented— 

 B. influenzae causes epidemics simulating coryza, rheumatic fever, typhoid 

 fever, cerebrospinal fever. 



(5) Same train of symptoms follows infection by different organisms 

 — typical rabies due to B. rfipA,— typical scarlet fever, cerebrospinal fever 

 and influenza due to M. catarrhalig—ijpic&\ cerebrospinal fever due to 

 B. typhosus and to Klebs-Loeffler bacillus— symptoms resembhng diphtheria 

 due to pneumococcus — typical typhoid fever due to B. coli. 



III. Vakiation in lesions pboduckd — studied in two ways — lesions pro- 

 duced during disease and by artificial inoculation in animals. 1. Variations 

 in lesions produced during disease. In many cases characteristic — not 

 invariably so — lesions typical of one infection may be produced by a different 

 one — lesions influenced by other factors than species of organism — e.g. age 

 of patient, route of invasion, secondary infection, treatment, etc. — possibility 

 of excluding such factors by inoculation. 2. Variation in lesion caused by 

 artificial inoculation. Method "standardises" lesion — lesions said to be 

 invariable under these conditions. B. pseudo-diphtheriae distinguished 

 from B. coli — avian tubercle bacillus disting^uished from human type — 

 S. mastitidis distinguished from S. anginosa and S. pyogenes — pneumo- 

 coccus of lobar pneumonia distinguished from that of lobular pneumonia. 

 Are the lesions caused by artificial means invariable? — certainly very 

 constant — e.g. tubercle bacillus — but not absolutely fixed— e.g'. a strain of 

 B. diph. causes lesions of rabies — a strain of S. mastitidis loses its power 

 to cause typical lesion — various types of tubercle bacilli fail to cause their 

 typical lesions. Two strains causing different lesions aiise from single strain 

 during cultivation — D. lanceolatus capsulatits isolated from different organs 

 causes different lesions — type of lesion altered if organism first grown 

 anaerobically. Every aspect of pathogenicity subject to variation. 



Other characters of bacteria equally variable. (94 — 106) 



CHAPTER VIII 



THE POSSIBLE OCCURRENCE OP TRANSMUTATION 

 IN THE LIVING BODY 



Organisms closely resembling each other except in pathogenicity often 

 found associated — can one of these be a derivative of the other? — e.g. 

 B. anthracis and B. anthracoides, in hides of cattle. Other instances in 

 the human body. B. coli and B. typhosus. Klebs-Loeffler bacillus and 

 ffofmann's ftfflciYto —pathogenesis — fermenting properties — seasonal pre- 

 valence — during convalescence from diphtheria — recent work. Staph. 

 epidermidis and staph, pyogenes — ^pathogenesis — fermenting properties — 



