180 THE FLOATING-MATTER OF THE AIR. 



§ 16. Freliminary Experiments on the Resistance- 

 limit of GerTTis to the temperature of Boiling Water. 



While continuing the conflict and experiencing the 

 defeats recorded in the foregoing pages, a remark of 

 Professor Lister's sometimes occurred to me. To apply 

 the antiseptic treatment with success, the surgeon must, 

 he holds, be interpenetrated with the conviction that 

 the germ theory of putrefaction is true. He must not 

 permit occasional failures to produce scepticism, but, on 

 the contrary, must probe his failures, in the belief that 

 his manipulation, and not the germ-theory, is at fault. 

 This may look like operating under a prejudice ; but 

 Professor Lister's maxim is nevertheless consistent with 

 sound philosophy and good sense ; and if I permitted a 

 bias to influence me in this inquiry, it was one fairly 

 founded on antecedent knowledge, which led me to 

 conclude that the long line of failures above referred 

 to would eventually be traced to my ignorance of the 

 conditions whereby perfect freedom from contamination 

 was to be secured. 



I laboured to discover these conditions, and to learn 

 something more regarding the nature of the contami- 

 nation — its origin, persistence, and manner of action. 

 When these researches began, five minutes' boiling, as 

 I have frequently stated, suflBced to sterilize the most 

 diversified infusions. Here we have frequently extended 

 the time of boiling to ten and fifteen minutes, and, 

 in some cases glanced at above, to immensely longer 

 periods, without producing this result. I desired more 

 exact knowledge as to the limit of endurance, and with 

 this view, on the 22nd of December, had six ' pipette 

 bulbs'charged with an infusion of cucumber, sp. gr. 1004. 

 They were then plugged with cotton-wool, hermetically 

 sealed, and subjected to the boiling temperature for 10 



