18/7.] 



Putrefactive and Infective Organisms. 



231 



Though the precautions taken to avoid contamination were far more 

 stringent than those observed in my first inquiry, and though the in- 

 terval of boiling was sometimes tripled in duration, these infusions, in 

 almost every instance, broke down. Spontaneously purified air, filtered 

 air, and calcined air (calcined, I may add, with far greater severity than 

 was found necessary a year previously) failed, in almost all cases, to 

 protect the infusions from putrefaction. 



I was sometimes cheered by a success which, at the time of its occur- 

 rence, would seem to be the result of increased severity in the methods 

 of experiment. But the success was subsequently so opposed by failure 

 that it finally stood out rather as an accident than as the normal result 

 of the inquiry. 



I had the most implicit confidence in the correctness of my earlier 

 experiments ; indeed incorrectness would have led to consequences 

 exactly opposite to those arrived at. Errors of manipulation would have 

 filled my tubes and flasks with organisms, instead of leaving them trans- 

 parent and void of life. By the unsuccessful experiments above referred 

 to a clear issue was therefore raised : — Either infusions of fish, flesh, and 

 vegetables had become endowed in 1876 with an inherent generative 

 energy which they did not possess in 1875, or some new contagium ex- 

 ternal to the infusions, and of a far more obstinate character than that 

 of 1875, had been brought to bear upon them at the later date. The 

 scientific mind will not halt in its decision between these two alterna- 

 tives. 



Eor my own part the gradual but irresistible interaction of thought and 

 experiment made it in the first instance probable, and at last certain, that 

 the atmosphere in which I worked had become so virulently infective as 

 to render utterly impotent precautions against contamination and modes 

 of sterilization which had been found uniformly successful in a less con- 

 taminated air. I therefore removed from the laboratory, first to the top, 

 and afterwards to the basement of the Eoyal Institution, but found that 

 even here, in a multitude of cases, failure was predominant, if not 

 uniform. This hard discipline of defeat was needed to render me 

 acquainted with all the possibilities of infection involved in the con- 

 struction of my chambers and the treatment of my infusions. 



I finally resolved to break away from the Eoyal Institution, and to 

 seek at a distance from it a less infective atmosphere. In Kew G-ardens, 

 thanks to our Eresident, the requisite conditions were found. I chose 

 for exposure in the Jodrell laboratory the special infusions which had 

 proved most intractable in the laboratory of the Eoyal Institution. The 

 result was that liquids which in Albemarle Street resisted two hundred 

 minutes' boiling, becoming afterwards crowded with organisms, were 

 utterly sterilized by five minutes' boiling at Kew. 



A second clear issue is thus placed before the Eoyal Society : — Either 



