THE WONDERS OF LIFE 



physical or chemical causes on mechanical principles. 

 Not a single fact compels us to assume a "vital force." 



Especially noteworthy in regard to the physiological 

 character of these lowest organisms are their bionomic 

 peculiarities, especially the indifference to external in- 

 fluences, higher and lower temperatures, etc. Many 

 of the chromacea live in hot springs, with a temperature 

 of fifty to eighty degrees centigrade, in which no other 

 organism is found. Other species may remain for a 

 long time frozen in ice, and resume their vital activity 

 as soon as it thaws. Many chromacea may be com- 

 pletely dried up, and then resume their life if put in 

 water after several years. 



Next in order to the chromacea we have the bacteria, 

 the remarkable little organisms which have been well 

 known in the last few decades as the causes of fatal 

 diseases, and the agents of fermentation, putrefaction, 

 etc. The special science which is concerned with them — 

 modern bacteriology — has attained so important a posi- 

 tion in a short period — especially as regards practical 

 and theoretical medicine — that it is now represented by 

 separate chairs at most of the universities. We may 

 admire the penetration and the perseverance with which 

 scientists have succeeded, with the aid of the best 

 modern microscopes and methods of preparation and 

 coloring, in making so close a study of the organism of 

 the bacteria, determining their physiological properties, 

 and explaining their great importance for organic life 

 by careful experiments and methods of culture. The 

 bionomic or economic position of the bacteria in 

 nature's household has thus secured for these tiny 

 organisms the greatest scientific and practical interest. 



However, we find that certain general views have been 

 maintained by specialists in bacteriology up to our own 

 time which are in curious contrast with these brilliant 

 results. The biologist who studies the systematic 



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