12 



INTRODUCTION 



performed by Schroder and Von Dusch in 1854. These work- 

 ers substituted cotton for the sulphuric acid and heat which 

 had formerly been used and showed that when air was drawn 

 through cotton and allowed to come in contact with putres- 



FIG. 3. Schwann's Experiment. Air is allowed to enter the flask only after it 

 was heated in the hot coiled tube. After Lafar. 



cible material that had been sufficiently heated there was no 

 putrefaction. These results were regarded by scientific men 

 as definitely settling the question. 



Modern Period. A Frenchman, Pouchet, director of the 

 Natural History Museum of Rouen, reopened the question 

 in 1859 upon theoretical considerations. Pasteur, in 1860, 

 entered this field, and with remarkable ingenuity and skill 

 refuted the conclusions of Pouchet and his followers. While 



