8 THE LIFE OF PASTEUB 



A few months later, on r 17, 1878, he read to the 



Academy a | further developments of his prin- 



ciples. In order thai beer should become altered and become 

 sour, putrid, si: acid or lactic, it is necessary that 



foreign organisms should develop within it, and those or- 

 ganisms only appear and multiply when those germs are 

 air nt in the liquid mass." It is possible to oppose 



th- taction oi those germs; Pasteur drew on the black- 



board the , of an apparatus which only communicated 



with the outer air by means of tubes fulfilling the office of 

 the sinuous necks of the glass vessels he had used for his 

 experiments on so-called spontaneous generation. He entered 

 into every detail, demonstrating that as long as pure yeast 

 alone had been sown, the security was absolute. " That which 

 has I" i :i put forward on the subject of a possible transforma- 

 tion of yeast into bacteria, vibriones, mycoderma aceti and 

 vulgar mucors, or vice versa, is mistaken." 



He wrote in a private letter on the subject : " These simple 

 and clrar results have cost me many sleepless nights before 

 presenting themselves before me in the precise form I have 

 now given them.*' 



But his own conviction had not yet pe; d the minds 



of his adversaries, and M. Trecul was still supporting his 

 hypothesis of transformations, the so-called proofs of which, 

 according to ,r, rested on a basis of confused facts tainted 



with involuntary errors due to imperfect experiments. 



In ober, 1873, at a sitting of the Academy, he pre- 



sented M. Trecul with a few little flagons, in which he had 

 sown some pur | of penicillium glaucum, begging him to 



aCl ' ! " u»d to observe them at his Leisnn ring him 



that ,t would be impossible to find a trace of any transformation 

 of t int.. y< • lis. 



"When M .! ins finished the little task which I am 



Soliciting of his devotion to the knowledge of truth " con 

 t,nu : ' • ,,r - " T rial! give him the elements of a'aimilar 



lerma omi; in other word.. I shall brin^ to 

 *■ ]uir] y paw mycoderma run with which 



he r.u, reprodua his former experiments and recognize the 



*hich I have lately announced " 

 ; fhus: "Th. v will allow me to 



™ " n " ^ PBmw * Tt ™' I that my contra- 



dictors have !„ uharly unlucky in taking the occasion 



