BACTERIA AND THEIR EFFECTS. 399 



BACTERIA AND THEIR EFFECTS. 



By L. A. STIMSON, A.M., M.D. 



LIVING organisms, microscopical in size, of the simplest, most 

 elementary nature, and moving freely in different liquids, have 

 been known to observers for nearly two hundred years. Scientific 

 classification and description were long impossible, on account of the 

 meagre facilities furnished by the microscopes of the last century ; but, 

 during the last fifty years, the means of observation have been so 

 much improved, and the number of observers has been so great, that 

 the advance in our knowledge of microscopical bodies compares favor- 

 ably with that in other branches of science. This advance has been 

 greatly stimulated by a tendency to see in low vegetable or animal 

 organisms the exciting cause not only of fermentation and decomposi- 

 tion, but also of many diseases. Pasteur's researches into the nature 

 and causes of fermentation, the lectures and publications of Tyndall 

 and Huxley, and the bitter discussions about spontaneous generation, 

 have made us all familiar with the names bacteria, vibriones, and micro- 

 cocci, or microzymas, with which we associate the idea of microscopi- 



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Fig. 1. a, Micrococci ; d, Micrococci, multiplying by scission : b, c. Bacteria (rod Bacteria, B. 

 termo ; e, vibrioses; f, h, i, k, Torulae, or Yeast-Plant, sprouting; g, probably "Dauer- 

 sporen," durable or resting spores. 







cal bodies, round, oval, or rod-like and jointed, varying in length from 

 five ten-thousandths to one one-hundredth of a millimetre, and found 

 especially in putrefying vegetable and animal infusions. The term 

 micrococcus has always been restricted to the small, round, or ovoid 

 bodies, but bacterium and vibrio have been applied indiscriminately to 

 all, the former being more commonly used in France and Germany, 

 the latter in England. When used in the narrower sense, bacteria 

 denotes stiff, rod-like bodies, single or jointed, motionless or endowed 

 with an oscillatory movement in place, while vibrio is applied to those 

 which move rapidly across the field of the microscope with an undula- 



