6 MICROBIOLOGY 



horst 7 shared this opinion and classed them with the Oscil- 

 laria. Since that time most naturalists have placed them 

 as the lowest class of the vegetable kingdom. Haeckel 8 

 relegated bacteria to the Protista, beside the Monas ; Pas- 

 teur regarded them as Infusoria. De Bary 1 , Balbiani 2 , 

 Kiinstler 3 , and Biitschli* placed them with the Flagel- 

 lates. 



The name Bacteria was proposed by Cohn in 1872. The 

 term Microbe, introduced by Sedillot in 1878, belongs not 

 only to the bacteria but also to the Yeasts, Moulds, and Pro- 

 tozoa ; the same is true of the popular term Microorganism. 



In protozoology the discovery of the malarial plasmo- 

 dium by Laveran in 1880; of the piroplasma of Texas fever 

 and its transmission by means of the cattle tick by Smith 

 and Kilborne in 1889 ; and the discovery of the trypanosomes 

 that are the cause of certain diseases of animals, laid the 

 foundation for the enormous amount of work that has been 

 done in determining the existing relation between protozoa 

 and certain diseases in animals and in man. 



The earlier work in bacteriology and parasitic proto- 

 zoology had for its purpose the finding of the cause of the 

 different infectious diseases. 



The discovery of tuberculin by Koch in 1890, and the 

 production of antitoxin in the blood of animals infected 

 with certain bacteria such as those of diphtheria and tetanus 

 by von Behring, Roux and others, led to investigations con- 

 cerning tissue resistance and reaction to microorganisms 

 and alien substances of a protoplasmic nature. This resulted 

 in the development of the present theories of immunity as 



7 Rabenhorst. Flora europaea Algarum, 1865. 



8 Haeckel. Le Regne des Protistes, 1879. 



1 De Bary. Morphologie 'und Biologic der Pilze, Mycetozoen und 

 Bacterien, 1884. 



2 Balbiani. Jour de micr., 1886 et suiv. 



3 Kiinstler. De la position systematique des Bacteriacees (Jour. 

 de micr., 1885). 



* Butschli. Ueber den Bau der Bacterien und verwandter Or- 

 ganismen, 1890. 



