IH4 FKAGMENTS OF SCIENCE. 



no fungi were developed. Only, therefore, in the four 

 cases where the infusions were cold infusions, and the 

 air ordinary air, did fungi appear. 



Dr. Bennett does not draw from his experiments the 

 conclusion to which they so obviously point. On them, 

 on the contrary, he founds a defence of the doctrine of 

 spontaneous generation, and a general theory of sponta- 

 neous development. So strongly was he impressed with 

 the idea that the germs could not possibly pass through 

 his potash and sulphuric acid tubes, that the appear- 

 ance of fungi, even in a small minority of cases, where 

 the air had been sent through these tubes, was to him 

 conclusive evidence of the spontaneous origin of such 

 fungi. And he accounts for the absence of life in many 

 of his experiments by an hypothesis which will not bear 

 a moment's examination. But, knowing that organic 

 particles may pass unscathed through alkalies and acids, 

 the results of Dr. Bennett are precisely what ought 

 under the circumstances to be expected. Indeed, their 

 harmony with the conditions now revealed is a proof of 

 the honesty and accuracy with which they were executed. 



The caution exercised by Pasteur both in the exe- 

 cution of his experiments, and in the reasoning based 

 upomthem, is perfectly evident to those who, through 

 the practice of severe experimental enquiry, have ren- 

 dered themselves competent to judge of good experi- 

 mental work. He found germs in the mercury used to 

 isolate his air. He was never sure that they did not 

 cling to the instruments he employed, or to his own 

 person. Thus when he opened his hermetically sealed 

 flasks upon the Mer de Glace, he had his eye upon the 

 file used to detach the drawn-out necks of his bottles ; 

 and he was careful to stand to leeward when each flask 

 was opened. Using these precautions, he found the 

 glacier air incompetent, in nineteen cases out of twenty, 



