APPENDIX, 399 



point in question. Besides, if M. Fremy had wished to test the 

 truth of his explanation, there was a very simple means of 

 restoring the purity of the air in contact with the liquids open 

 to him ; he might have passed through his vessels a slow and 

 continuous current of pure air, day and night. We have done 

 this a hundred times, and we have always found that the 

 sterility of the putrescible or fermentable liquids remained 

 unaffected. 



The hemi-organism hypothesis is, therefore, absolutely un- 

 tenable, and we have no doubt that our learned friend will 

 eventually declare as much before the Academy, since he has 

 more than once publicly expressed his readiness to do so as 

 soon as our demonstrations appear convincing to him. How 

 can he resist the evidence of such facts and proofs ? Persistence 

 in such a course can benefit nobody, but it may depreciate the 

 dignity of science in general esteem. It would gratify us 

 extremely to find the rigorous exactness of our studies on this 

 subject acknowledged by M. Fremy, and regarded by that 

 gentleman with the same favour bestowed upon it everywhere 

 abroad. It may be doubted if there exists at the present day a 

 single person beyond the Rhine who believes in the correctness 

 of Liebig's theory, of which M. Fremy's hemi-organism is 

 merely a variation. If M. Fremy still hesitates to accept our 

 demonstrations, the observations of Mr. Tyndall may effect his 

 conversion. 



The other publication to which we alluded was the work of 

 the celebrated English physicist, John Tyndall. It was read 

 before the Royal Society of London, at a meeting held on 

 January 13, 1876. 



The following letter explains how the illustrious successor of 

 Faraday at the Royal Institution came to undertake these 

 researches : — 



'' London, February 16, 1876. 



" Dear Mr. Pasteur, — 



" In the course of the last few years a number of works 



