VITALITY OF PUTKEFAOTIVE OEGAHISMS. 165 



Lours ; the iafusion was filtered, boiled, and such pre- 

 cipitated matter as appeared on boiling was removed by 

 refiltering. The liquid thus prepared was introduced 

 into five thick glass tubes, which were hermetically 

 sealed, placed in a cold oil-bath, gradually heated to 

 230°, and maintained at that temperature for a quarter 

 of an hour. The tubes being removed and permitted 

 to cool, the infusion was introduced into a chamber of 

 six tubes, and boiled there for five minutes. 



The previous superheating of the infusion did not 

 even retard the development of life, for in less than two 

 days every tube in the chamber swarmed with Bacteria. 

 Thus far, then, every attempt at a solution was unsuc- 

 cessful. 



But why, it may be asked, attempt such solutions ? 

 Was it not mere prejudice against the doctrine of spon- 

 taneous generation that prevented me from frankly 

 submitting to the apparent logic of facts, and admitting 

 the experiments just recorded to be a demonstration of 

 the doctrine ? By no means. The only prejudice I 

 feel is the wholesome repugnance to accepting momen- 

 tous conclusions on insufficient grounds. Hume's cele- 

 brated argument has its application here. Taking an- 

 tecedent experience fully into account, it was far easier 

 for me to believe my knowledge imperfect, or my 

 present work erroneous, than to believe the doctrine of 

 spontaneous generation true. 



§ 11. New Expermients on Animal Infusions. 

 Contradictory results. 



In the course of this inquiry I was continually re- 

 minded of my experiments in 1875, when the most 

 complete immunity from Bacterial or fungoid life was 

 so readily secured. I had operated many times with 



