2 BACTERIOLOGY FOR NURSES 



During the following one hundred and fifty years little advance 

 was made. Observers, for the most part, were content with simply 

 seeing these minute organisms and marveling at the wonders of 

 nature. 



In 1762 Marcus Antonius von Plenciz, a physician of Vienna, 

 published his views on the germ theory of infectious diseases. 

 He insisted that an infectious disease had as its cause its own 

 specific germ and that infective material must contain the living 

 causal agent of the disease. 



A decided advance was made by Ehrenberg. In his principal 

 work published in 1838 upon " infusion animals " he described 

 the difference between the larger forms and conferred upon his 

 " animals " some of the names still current in bacteriological 

 nomenclature. 



Very soon the question arose as to the origin of these micro- 

 organisms. Were they reproduced from similar preexisting forms 

 (the so-called vitalistic theory) or were they the result of spon- 

 taneous generation due to changes in the material in which they 

 were found. Liebig and his supporters held the view that fer- 

 mentation and putrefaction were simply chemical processes, and 

 that all albuminoid bodies would if left to themselves disintegrate 

 into smaller molecules. The force of Liebig' s authority over- 

 shadowed for some time the vitalistic theory until Pasteur (1822- 

 1895) proved that albuminous material had no natural tendency 

 to disintegrate, and that putrefaction and decay did not produce 

 " spontaneous generation of life," but on the contrary were manifes- 

 tations of the presence of living and growing organisms engaged 

 in satisfying their need of food, and that like all larger animals 

 and plants these organisms come into existence only by means of 

 reproduction. 



As a result of the researches of Pasteur the study of the causal 

 relation of bacteria to disease was taken up with renewed vigor. 

 Investigations into the cause of certain infectious diseases in plants 

 and insects placed the doctrine upon a firm foundation ; later 

 it was demonstrated that microorganisms were responsible for 

 certain infectious diseases in man and animals also. To Davaine, 



