xii FOREWORD 



the way in their experiments, and the latter had reached the 

 conclusion that there is no vegetable and no animal that has 

 not its own germ. But heterogenesis became the burning 

 question, and Pouchet in France, and Bastian in England, 

 led the opposition to Pasteur. The many famous experiments 

 carried conviction to the minds of scientific men, and destroyed 

 for ever the old belief in spontaneous generation. All along 

 the analogy between disease and fermentation must have been 

 in Pasteur's mind; and then came the suggestion: "What 

 would be most desirable would be to push those studies far 

 enough to prepare the road for a serious research into the origin 

 of various diseases." If the changes in lactic, alcohol and 

 butyric fermentations are due to minute living organisms, why 

 should not the same tiny creatures make the changes which 

 occur in the body in the putrid and suppurative diseases. With 

 an accurate training as a chemist, having been diverted in his 

 studies upon fermentation into the realm of biology, and 

 nourishing a strong conviction of the identity between putre- 

 factive changes of the body and fermentation, Pasti-ur was well 

 prepared to undertake investigations, which had hitherto been 

 confined to physicians alone. 



The first outcome of the researches of Pasteur upon fermenta- 

 tion and spontaneous generation represents a transformation 

 in the practice of surgery, which, it is not too much to say, 

 has been one of the greatest boons ever conferred upon 

 humanity. It had long been recognised that now and again 

 a wound healed without the formation of pus, that is without 

 suppuration, but both spontaneous and operative wounds were 

 almost invariably associated with that change; and, moreover, 

 they frequently became putrid, as it was then called — infected, 

 as we should say; the general system became involved, and 

 the patient died of blood poisoning. So common was this, 

 particularly in old, ill-equipped hospitals, that many surgeons 

 feared to operate, and the general mortality in all surgical cases 

 was very high. Believing that from outside the germs came 

 which caused the decomposition of wounds, just as from the 

 atmosphere the sugar solution got the germs which caused 



