INTRODUCTION 19 



Ehrenberg (1838) began his classification of animalcules and in his 

 group of Vibrionia described several "species" of organisms, as follows: 



1. Bacterium rigid and filamentous organisms. 



2. Vibrio flexuous and filamentous organisms. 



3. Spirillum rigid spiral filamentous organisms. 



4. Spirocheta flexuous spiral filamentous organisms. 



This classification, which contains terms widely used in bacterial 

 nomenclature today, was followed in 1872 by the important contribu- 

 tions of Cohn upon "Bacteria," the starting-point of modern bacterial 

 classification. 



The diseases of man naturally attracted much attention and in 1839 

 Schoenlein examined the crusts of that disease of the scalp known as 

 favus with the microscope and found the mycelia of the fungus now 

 known in his honor as Achorion schoenleinii. 



The extensive studies of Pasteur upon yeasts and the "diseases" 

 of beer and wine, upon the diseases of the silk worm (pebrine and 

 flacherie), upon furunculosis and puerperal sepsis, 1 upon anthrax 

 and anthrax immunization (attenuated viruses) chicken cholera, and 

 somewhat later, rabies laid broad foundations for the development 

 of the science of bacteriology. 



Among the most important technical discoveries which have con- 

 tributed to the development of bacteriology are: The improvement 

 in the achromatic lens (about 1835) and the perfection of the sub- 

 stage condenser (Abbe) ; the use of cotton for air filters in flasks and 

 test-tubes by Schroeder and von Dusch (1854), the sterilization of 

 culture media by heat (Pasteur, Tyndall, Koch and others), the 

 introduction of anilin dyes as staining reagents by Weigert and Ehrlich 

 (1877), and finally, the use of solid culture media and the plate method 

 for pure cultures by Koch in 1881. 



Sir Joseph Lister (1867) published an epoch-making contribution 

 entitled, "On the Antiseptic Principle of the Practice of Surgery," 

 in which is clearly set forth the importance of bacteria in surgery 

 and the principles of surgical asepsis that have revolutionized this 

 branch of medicine. 



About 1878 Koch isolated the anthrax bacillus in pure culture from 

 the blood of infected animals, grew the organisms for several generations 

 in the clear aqueous humor of the eye of the ox, and then reinjected 

 the organisms into experimental animals and reproduced the disease. 

 For the first time a specific microbe was clearly and convincingly 



1 Compt. rend. Acad. d. Sci., 1880, xc, 1033. 



