594 THE POPULAR SCIENCE MONTHLY. 



clinched by an experiment which will remove every residue of doubt 

 as to the ability of the infusions to sustain life. We open the back- 

 doors of our sealed chambers, and permit the common air with its 

 floating particles to have access to our tubes. For three months they 

 have remained pellucid and sweet flesh, fish, and vegetable extracts, 

 purer than ever cook manufactured. Three days' exposure to the 

 dusty air suffices to render them muddy, fetid, and swarming with 

 infusorial life. The liquids are thus proved, one and all, ready for 

 putrefaction when the contaminating agent is applied. I invite my 

 colleague to reflect on these facts. How will he account for the abso- 

 lute immunity of a liquid exposed for months in a warm room to opti- 

 cally pure air, and its infallible putrefaction in a few days when 

 exposed to dust-laden air? He must, I submit, bow to the conclusion 

 that the dust-particles are the cause of putrefactive life. And, unless 

 he accepts the hypothesis that these particles, being dead in the air, 

 are, in the liquid, miraculously kindled into living things, he must 

 conclude that the life we have observed springs from germs or organ- 

 isms diffused through the atmosphere. 



The experiments with hermetically-sealed flasks have reached the 

 number of 940. A sample group of 130 of them were laid before the 

 Royal Society on January 13, 1876. They were utterly free from life, 

 having been completely sterilized by three minutes' boiling. I took 

 special care that the temperatures to which the flasks were exposed 

 should include those previously alleged to be efficient. I copied, 

 indeed, accurately the conditions laid down by our most conspicuous 

 heteroo-enist, but I failed to corroborate him. He then laid stress on 

 the question of warmth, suddenly adding 30 to the temperatures 

 with which both he and I had previously worked. Waiving all argu- 

 ment or protest against the caprice thus manifested, I met this new 

 requirement also. The sealed tubes, which had proved barren in 

 the Royal Institution, were suspended in perforated boxes, and 

 placed under the supervision of an intelligent assistant in the Turkish 

 Bath in Jerrayn Street. From two to six days had been allowed for 

 the generation of organisms in hermetically-sealed tubes. Mine re- 

 mained in the washing-room of the bath for nine days. Thermome- 

 ters placed in the boxes, and read off twice or three times a day, 

 showed the temperature to vary from a minimum of 101 to a maxi- 

 mum of 112 Fahr. At the end of nine days the infusions were as 

 clear as at the beginning. They were then removed to a warmer 

 position. A temperature of 115 had been mentioned as particularly 

 favorable to spontaneous generation. For fourteen days the tempera- 

 ture of the Turkish bath hovered about this point, falling once as low 

 as 106, reaching 116 on three occasions, 118 on one, and 119 on 

 two. The result was quite the same as that just recorded. The high- 

 er temperatures proved perfectly incompetent to develop life. 



Taking the actual experiment we have made as a basis of calcula- 



