248 CRITIQUES AND ADDRESSES. [x. 



guided by that theory, he has devised a method of extir- 

 pating the disease, which has proved to be completely 

 successful wherever it has been properly carried out. 



There can be no reason, then, for doubting that, among 

 insects, contagious and infectious diseases, of great 

 malignity, are caused by minute organisms which are 

 produced from pre-existing germs, or by homogenesis ; 

 and there is no reason, that I know of, for believing 

 that what happens in insects may not take place in the 

 highest animals. Indeed, there is already strong evi- 

 dence that some diseases of an extremely malignant 

 and fatal character to which man is subject, are as much 

 the work of minute organisms as is the Pebrine. I refer 

 for this evidence to the very striking facts adduced by 

 Professor Lister in his various well-known publications 

 on the antiseptic method of treatment. It appears to 

 me impossible to rise from the perusal of those publica- 

 tions without a strong conviction that the lamentable 

 mortality which so frequently dogs the footsteps of the 

 most skilful operator, and those deadly consequences of 

 wounds and injuries which seem to haunt the very walls 

 of great hospitals, and are, even now, destroying more 

 men than die of bullet or bayonet, are due to the 

 importation of minute organisms into wounds, and their 

 increase and multiplication ; and that the surgeon who 

 saves most lives will be he who best works out the 

 practical consequences of the hypothesis of Eedi. 



I commenced this Address by asking you to follow me 

 in an attempt to trace the path which has been followed 

 by a scientific idea, in its long and slow progress from the 

 position of a probable hypothesis to that of an estab- 

 lished law of nature. Our survey has not taken us into 

 very attractive regions ; it has lain, chiefly, in a land 

 flowing with the abominable, and peopled with mere 

 grubs and mouldiness. And it may be imagined with 



