HISTORY OF MICROBIOLOGY. 3 



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

 always produced through the agency of pre-existing 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-quar- 

 ters of an hour was possible only, provided air, which had not been pre- 

 viously exposed to the influence of fire, had been admitted." Objections 

 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 spontane- 

 ous 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 1840-1860. 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 numerous wheels of the 

 mills of Mayence." Again and again Liebig formally denied the correct- 

 ness 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. 



In 1841 Fuchs investigated some blue and yellow milk. He exam- 

 ined it with the microscope and discovered the presence of organisms. 



