CHAPTEE VI. 



The Pathogenic Bacteria; Anthrax Bacillus; Bacillus of Malignant CEdema; 

 Tubercle Bacillus; Lepra Bacillus; Syphilis BaciUus; Bacillus of Glanders; 

 Asiatic Cholera Bacillus; Pinkler-Prior's Vibrio; Deneke's Vibrio; Vibrio 

 MetschnikofE (Gamaleia); Emmerich's Bacillus; Bacillus Typhosus; Spi- 

 rillum of Relapsing Fever; Plasmodium Malari»; Friedlander's Pneu- 

 mococcus; Fraenkel's Pneumocoocus; Diphtheria Bacillus; Bacillus of 

 Rhinoscleroma; Pyogenic Bacteria; Staphylococcus Pyogenes Aurens; 

 Staphylococcus Pyogenes Citreus; Streptococcus Pyogenes; Bacillus 

 Pyocyaneus; Bacillus Pyocyaneus B. (Ernst); Gonocoocus; Tetanus 

 Bacillus; Bacteria of Septiciemia Hemorrhagica; Bacillus of Hog Ery- 

 sipelas; Mice Septicaemia Bacillus; Micrococcus Tetragenus. 



THE PATHOGENIC BACTERIA. 



With regard to the strictly pathogenic infectious bacteria, a 

 careful selection, a conscientious sifting of the very extensive mass 

 of material which our young science pours in upon us in daily-in- 

 creasing quantity, is far more requisite than with the harmless 

 species. It has been recognized that the facts discovered by 

 modern bacteriology are of extreme importance in understanding 

 diseased conditions, and consequently a flood of enthusiastic, active 

 research has poured over the newly-opened fleld of investigation. 



The desire to make discoveries has been great, and there is now 

 scarcely a malady which can be supposed due to parasites which 

 has not been referred to some particular micro-organism. Most of 

 them, it is true, will not long retain the position to which they have 

 been raised, and this whole system of jumping at conclusions would 

 be harmless enough did it not offer a serious danger for the further 

 development of our science. If false ideas of the progress already 

 made gain credit, we lose the clear perception of what still remains 

 to be done. 



Those things will be treated of which will bear a strict criticism, 

 and onlj'' well-founded facts and reliable observation will be consid- 

 ered, and therefore the limits of our present knowledge may appear 

 somewhat narrower, perhaps, than expected. 



It need not be repeated that we recognize a bacterium as the 

 undoubted exciter of morbid affection only when it is proved to be 



