238 SCIENCE PROGRESS. 



the moist sides of the narrow neck being sufficient to pre- 

 vent the entrance to the flask of any solid particulate matter 

 that may be suspended in the air. Such a flask may be 

 kept in an incubator for months perfectly unchanged, but 

 as soon as the narrow neck is nipped off, and particles are 

 allowed to fall in, and with these particles the seeds or 

 germs of moulds or bacteria, these organisms soon make 

 their appearance, and the process of putrefaction goes on 

 apace. M. Radot says, "lastly, to convince the most pre- 

 judiced minds and to leave no contradiction standing, Pas- 

 teur showed one of these bulbs with the sinuous neck which 

 he had prepared and preserved for months and years. The 

 bulb was covered with dust. ' Let us,' said he, ' take up a 

 little of this outside dust on a bit of glass, porcelain, or 

 platinum, and introduce it into the liquid ; the following 

 day you will find that the infusion, which up to this time 

 remained perfectly clear, has become turbid, and that it 

 behaves in the same manner as other infusions in contact 

 with ordinary air.' If the bulb be so tilted as to cause a 

 little drop of the clear infusion to reach the extremity of 

 the bent part of the neck where the dust particles are ar- 

 rested, and if this drop be then allowed to trickle back into 

 the infusion, the result is the same — turbidity supervenes 

 and the microscopic organisms are developed. Finally, if 

 one of these bulbs which have stood the test of months and 

 years without alteration be several times shaken violently, 

 so that the external air shall rush into it, and if it be then 

 placed once more in the stove, life will soon appear in it." 



For his work on this subject Pasteur received the Prize 

 of the Academy of Sciences, which was awarded to him 

 "for his well-contrived experiments to throw new light upon 

 the question of spontaneous generation ". 



Tyndall in this country repeated and modified many of 

 Pasteur's experiments, and overthrew in the popular 

 mind the theories that had been advanced by our country- 

 man Needham, although at the time these had been 

 successfully controverted in argument by Spallanzani. Dr. 

 — now Sir William — Roberts, and Professor — now Sir 

 Joseph — Lister performed a number of corroborative and 



