188 BACTEEIA. 



BACTERIA. 



BY D. B. WARD, M.D. 



Although bacteriology, as a science, is only twenty years 

 old or less, the bacteria have been known to scientific 

 men for more than 200 years. 



Van Leenwenhoeck, "the father of microscopy,'' dur- 

 ing the 17th century made a great number of powerful 

 little lenses, and with these simple microscopes he made 

 many interesting discoveries. 



He saw, in 1685, a number of very small rod-like bodies 

 swimming about in stagnant water, and afterwards found 

 that similar bodies existed in tartar from the teeth and in 

 the dejections of diarrhoea. They moved, hence, accord- 

 ing to the logic of that time, they must be animals, for the 

 motion of plants, so frequently observed since, was then 

 unknown. In 1838 Ehrenberg, the great naturalist and 

 microscopist, who, perhaps of all men before or since, 

 possessed the greatest mania for scientific arrangement 

 and classification, could not letthese bodies, small though 

 they are, escape him. He had a fashion of putting on 

 good old Greek and Latin names to everything he could 

 find, and he was not always careful to ascertain whether 

 any one else had named the object before. Indeed he 

 sometimes renamed minute objects, having forgotten 

 that he himself originally described them. These minute 

 organisms are so small that they tax the powers of the 

 best microscopes and the best eyes of lo-day, and they 

 must have looked very small and very faint under the 

 instruments of that time.- 



Nevertheless Ehrenberg made a classification of four 

 genera, which he called bacterium, vibrio, spirillum and 

 spirochaete respectively, according to the shape of the 

 rods, whether fiexible or infiexible, curved or straight. 

 The name bacterium, or its plural, bacteria, is now ap- 



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