HEALTH AND DISEASE 303 



generation was wholly unnecessary to account for anything that happened 

 in his experiments, and as his experiments were expressly designed to cover 

 all the instances in which the phenomenon was supposed to occur, he left 

 his opponents with nothing to put forward but unverified suppositions. 



Pasteur made up a number of broths and infusions of organic matter 

 that very quickly fermented or went bad when left exposed to the air. As 

 Spallanzani had done before him, he put the infusions into small glass 

 flasks, heating them to destroy any spores or cells of living organisms and 

 then sealed the flasks. But this time he sealed them positively — by drawing 

 out the narrow necks and fusing the glass with a blowlamp. The infusions 

 kept clear and "good" indefinitely. When he broke the seal, thus permitting 

 a few cubic centimeters of air to rush in, the preparations promptly went 

 bad, and in a few days they were teeming with living organisms, all of 

 which had arisen from the multiplication and growth of the few micro- 

 scopic cells and spores let in with the air. He repeated the experiments, 

 sterilizing the air before admission by passing it through a red-hot platinum 

 tube. There was then no growth of organisms in the preparations and they 

 kept good. 



By 1863, both Pasteur and Ferdinand Cohn had reached the conclu- 

 sion that putrefaction of organic matter was a process of the same na- 

 ture as fermentation, also consequent upon the growth of living organisms. 

 The suppuration of surgical wounds was regarded as an instance of putre- 

 faction, and by 1865, Dr. Lister in England was excluding air-borne 

 germs from wounds with filter pads of cotton wool, and kilhng the germs 

 which settled on the skin, on instruments, and on exposed tissues during 

 operations, with carbolic acid as an antiseptic. 



The plant doctors were concerned with these new developments no less 

 than the medical profession. When plant tissue was cut or wounded, hosts 

 of smaller organisms, yeasts and bacteria, would get in from the air or the 

 soil and complete the work of decay. They could, for example, rot blighted 

 potatoes in the ground, reducing them to skinfuls of slime. The "vegetable 

 pathologists" would now have to study not only the moulds and mildews, 

 but the yeasts, the myxomycetes and the bacteria. 



Assuredly, those early researches of Louis Pasteur left the plant patholo- 

 gists with much to brood over, and their suggestiveness had not been ex- 

 hausted by 1947. 



