THE CELL-DOCTRINE 151 



disease but also the present practice of vaccination for a 

 variety of diseases. 12 



The germ-theory of disease stimulated renewed interest 

 in the problem of generation. If organisms originated 

 de novo or spontaneously, their appearance was due to con- 

 ditions within the medium in which they appeared. If they 

 arose from preexisting organisms by reproduction, their 

 appearance was due to conditions under which they obtained 

 entrance. Pasteur and other workers during the sixties and 

 seventies of the last century gave the death blow to the 

 theory of generation de novo. Microscopic forms were 

 shown to have life-cycles comparable with those of larger 

 organisms. Prevention and curation in a large class of 

 diseases became the problem of preventing the entrance and 

 effecting the destruction of parasitic germs. Contagion was 

 at length explained. 



Remarkable applications of the above principles appeared 

 in surgery. The surgical wards of the hospitals had formerly 

 been veritable pesthouses for wound-infections. No pre- 

 cautions availed. 13 Lord Joseph Lister (1827-1912) applied 

 to surgery the principles discovered by Pasteur. The sup- 

 puration of a wound was the putrefaction of organic ma- 

 terial. Putrefaction elsewhere was caused by microscopic 

 organisms. Exclude or destroy the organisms and there 

 would be no suppuration. Lister's results were amazing. 

 Surgery in which the germs were destroyed by means of 



12 Before Pasteur, certain general features of the germ-fact of disease and of 

 the reactions of the body to such invasions had been discerned, for example, the 

 discovery by Jenner (1796) of vaccination against smallpox. What Pasteur 

 did was to give the first complete demonstrations of diseases as caused by 

 parasitic organisms, of infection as merely the entrance of the parasites, and of 

 the control of germ-diseases by vaccinations. A host of facts long known to 

 the medical profession at once became intelligible. 



13 During the American Civil War hospitals were even torn down and new 

 ones constructed in vain attempts to stamp out gangrene. But all to no avail, 

 for the surgeons unknowingly carried the infection attached to their instru- 

 ments and persons. This leaven soon leavened the new establishment so that 

 wound-disease was again rampant. 



