BACTERIA AS PLANTS. 13 



recognised as a class of organisms by themselves 

 were not, indeed, distinguished from yeasts or 

 other minute animalculae. Their variety was not 

 mistrusted and their significance not conceived. 

 As microscopic organisms, there were no reasons 

 for considering them of any more importance 

 than any other small animals or plants, and their 

 extreme minuteness and simplicity made them of 

 little interest to the microscopist. On the other 

 hand, their causal connection with fermentative 

 and putrefactive processes was entirely obscured 

 by the overshadowing weight of the chemist Lie- 

 big, who believed that fermentations and putre- 

 factions were simply chemical processes. Liebig 

 insisted that all albuminoid bodies were in a 

 state of chemically unstable equilibrium, and if 

 left to themselves would fall to pieces without 

 any need of the action of microscopic organisms. 

 The force of Liebig's authority and the brilliancy 

 of his expositions led to the wide acceptance of 

 his views and the temporary obscurity of the re- 

 lation of microscopic organisms to fermentative 

 and putrefactive processes. The objections to 

 Liebig's views were hardly noticed, and the force 

 of the experiments of Schwann was silently ig- 

 nored. Until the sixth decade of the century, 

 therefore, these organisms, which have since be- 

 come the basis of a new branch of science, had 

 hardly emerged from obscurity. A few micros- 

 copists recognised their existence, just as they 

 did any other group of small animals or plants, 

 but even yet they failed to look upon them as 

 forming a distinct group. A growing number of 

 observations was accumulating, pointing toward 

 a probable causal connection between fermenta- 

 tive and putrefactive processes and the growth of 

 2 



