HISTORY OF MICROBIOLOGY 3 



In 1668, Francisco Redi, an Italian, distinguished alike as scholar, 

 poet, physician, and naturalist, expressed the idea that life in matter is 

 always produced through the agency of preexisting living matter; but 

 the beginnings of the real controversy date from the publication of 

 Needham's experiments in 1745. The English divine boiled some meat 

 extract in a flask, made the flask air-tight, and left it for some days. 

 When the flask was opened, he found in it what he termed "infusoria." 

 He naturally concluded that all life had been killed by boiling; and, 

 as the entrance of fresh life from the outside was prevented by the 

 closing of the flask, he considered that the living infusoria must have 

 originated spontaneously from the inanimate constituents of the broth. 



Twenty years later Abbe Spallanzani alleged that the development 

 of the infusoria "in an infusion maintained at boiling-point for three- 

 quarters of an hour was possible only, provided air, which had not been 

 previously exposed to the influence of fire, had been admitted." Ob- 

 jections were made to these experiments and the controversy went 

 merrily on. Gradually experimental evidence accumulated resulting 

 largely from the work of Franz Schulze, and the discovery by Schroeder 

 and Dusch in 1853, that putrescible fluids will not decay after boiling, if 

 protected from the bacteria of the air by means of a cotton-wool 

 filter or plug; and the epoch-making experiments of Pasteur in 1860, 

 with the now well-known Pasteur flask, showed conclusively that the 

 hypothesis of spontaneous generation, or abiogenesis, could not be 

 proved. 



Liebig, the celebrated German chemist, strenuously opposed the 

 theories of Pasteur; his authority and the brilliancy of his expositions 

 influenced the scientific world during the period 1840-60. To Liebig, 

 fermentation was a purely chemical phenomenon unassociated with any 

 vital process; and he treated Pasteur's results with disdain. "Those 

 who pretend to explain the putrefaction of animal substance by the 

 presence of microorganisms," he wrote, "reason very much like a child 

 who would explain the rapidity of the Rhine by attributing it to the 

 violent motions imparted to it in the direction of Bingen by the numer- 

 ous wheels of the mills of Mayence." Again and again Liebig formally 

 denied the correctness of Pasteur's assertions; finally Pasteur challenged 

 him to appear before the Academic Commission to which they would 

 submit their respective results. Liebig, however, did not accept the 

 challenge; the victory was with the French savant. 



