CHAPTER II. 

 HISTORICAL. 



It must be evident that the science of bacteriology had its inception with 

 the discovery of the compound microscope. For some time the progress 

 in bacteriological investigation continued parallel with the progress in the 

 mechanical perfection of the microscope and with the advance in microscop- 

 ical technic. Gradually, however, the chemical and physiological investi- 

 gations pertaining to bacteria gained in importance and significance. Our 

 knowledge of the morphology of bacteria as revealed through the compound 

 microscope has been practically stationary for two decades, but not so our 

 knowledge of b_cterial products and bacterial action. The methods of 

 bacteriological technology have been gradually perfected, and the prog- 

 ress along this line has kept pace with the chemical and physiological 

 investigations. 



Although, as indicated, the science of bacteriology is of comparatively 

 recent origin, yet we must not lose sight of the fact that many of the ideas 

 underljang this science, as now comprehended, were advanced in remote an- 

 tiquity. For this reason it is desirable to set forth these earlier concepts in a 

 historical review. Most of the writers on general bacteriology, who make 

 reference to the history of the subject, almost invariably mention the older 

 ideas regarding spontaneous generation as being the forerunners of the mod- 

 ern ideas of bacteriology. It is, however, the ancient theories and beliefs 

 pertaining to the cause of decay, disease, and epidemics which are even more 

 directly associated with the first more important discoveries pertaining to 

 modern bacteriological pathology. 



For the purposes of simplification, condensation, and greater clearness 

 the historical review is divided into periods or epochs. It is not possible, 

 in the following brief outline, to cite all investigations of importance. Only 

 a few of the epoch-making specialists are mentioned. 



Period I. 



From Hippocrates (300 B. C.) to Leeuwenhoek (1656). (The 

 earliest ideas regarding epidemics and spontaneous generation.) 



From the earliest times the more scholarly writers mentioned certain 

 noxious gaseous, and odoriferous substances or efBuvias as being the cause 

 of epidemics. These effluviaswere supposed to emanate from the soil, from 



5 



