218 THE LIFE OF PASTEUR 



contradictors as long as he believed in their good faith ; what 

 he wanted was that truth should have the last word. ' What 

 you lack, M. Fremy, is familiarity with a microscope, and you, 

 M. Tre"cul, are not accustomed to laboratories!", " M. 

 Fremy is always trying to displace the question," said Pasteur, 

 ten months after M. Balard's appeal. 



Whilst M. Fremy disputed, discussed, and filled the 

 Academic with his objections, M. Tre*cul, whose life was some- 

 what misanthropical and whose usually sad and distrustful 

 face was seen nowhere but at the Institute, insisted slowly, 

 in a mournful voice, on certain transformations of divers cells 

 or spores from one into the other. Pasteur declared that those 

 ideas of transformation were erroneous; but and there lay 

 the interest of the debate there was one of those transforma- 

 tions that Pasteur himself had once believed possible : that of 

 the mycoderma vini, or wine flower, into an alcoholic ferment 

 under certain conditions of existence. 



A modification in the life of the mycoderma when submerged 

 had led him to believe in a transformation of the mycoderma 

 cells into yeast cells. It was on this question, which had been 

 left in suspense, that the debate with Trecul came to an end, 

 leaving to the witnesses of it a most vivid memory of Pasteur's 

 personality inflexible when he held his proofs, full of scruples 

 and reserve when seeking those proofs, and accepting no per- 

 sonal praise if scientific truth was not recognized and honoured 

 before everything else. 



On November 11 Pasteur said : " Four months ago doubts 

 suddenly appeared in my mind as to the truth of the fact in 

 question, and which M. Tre*cul still looks upon as indisputable. 

 ... In order to disperse those doubts I have instituted the 

 most numerous and varied experiments and I have not suc- 

 ceeded through those four months in satisfying myself by irre- 

 fragable proofs ; I still have my doubts. Let this example 

 show to M. Trecul how difficult it is to conclude definitely in 

 such delicate studies." 



Pasteur studied the scientific point for a long time, for he 

 never abandoned a subject, but was ever ready to begin again 

 after a failure. He modified the disposition of his first tests, 

 and by the use of special vessels and slightly complicated 

 apparatus succeeded in eliminating the only imaginable cause 

 of error the possible fall, during the manipulations, of exterior 

 germs, that is, the fortuitous sowing of yeast cells. After that 



