BACTERIOLOGY AND PUBLIC 

 HEALTH 



CHAPTEE I 



THE BIOLOGY OF BACTERIA* 



Early work— Place of Bacteria in Nature— Biology of Bacteria; Morphology, 

 Composition, Reproduction, Influence of External Conditions — Light — 

 Modes of Bacterial Action — Seed and Soil— Specificity of Bacteria — 

 Association, Antagonism, Attenuation — Bacterial Diseases of Plants. 



The first scientist who demonstrated the existence of micro-organisms 

 was Antony von Leeuwenhoek. He was born at Delft, in Holland, 

 in 1632, and enthusiastically pursued microscopy with primitive 

 instruments. He corroborated Harvey's discovery of the circulation 

 of the blood, in the web of a frog's foot ; he defined the red blood 

 corpuscles of vertebrates, the fibres of the lens of the human eye, 

 the scales of the skin, and the structure of hair. He was neither 

 educated nor trained in science, but in the leisure time of his 

 occupation as a linenTdraper he learned the art of grinding lenses, 

 in which he became so proficient that he was able to construct a 

 microscope of greater power than had been previously manufactured. 

 The compound microscope dates from 1590, and when Leeuwenhoek 



* We propose throughout to use the term hacterium (pi. bacteria) in its generic 

 meaning, unless especially stated to the contrary. It will also be synonymous with 

 the terms microbe, germ, and micro-organism. The term bacillus will, of course, be 

 restricted to a rod-shaped bacterium. 



A 



