254 THE LIFE OF PASTEUR 



posed to come himself and experiment in the laboratory of 

 the Ecole Normale. 



" For nearly twenty years," said Pasteur, " I have pursued, 

 without finding it, a proof of life existing without an anterior 

 and similar life. The consequences of such a discovery would 

 be incalculable ; natural science in general, and medicine and 

 philosophy in particular, would receive therefrom an impulse 

 which cannot be foreseen. Therefore, whenever I hear that 

 this discovery has been made, I hasten to verify the assertions 

 of my fortunate rival. It is true that I hasten towards him 

 with some degree of mistrust, so many times have I experienced 

 that, in the difficult art of experimenting, the very cleverest 

 stagger at every step, and that the interpretation of facts is no 

 less perilous." 



Dr. Bastian operated on acid urine, boiled and neutralized 

 by a solution of potash heated to a temperature of 120 C. If, 

 after the flask of urine had cooled down, it was heated to a 

 temperature of 50 C. in order to facilitate the development of 

 germs, the liquid in ten hours' time swarmed with bacteria. 

 14 Those facts prove spontaneous generation," said Dr. Bastian. 



Pasteur invited him to replace his boiled solution of potash by 

 a fragment of solid potash, after heating it to 110 C. , in order to 

 avoid the bacteria germs which might be contained in the 

 aqueous solution. This question of the germs of inferior 

 organisms possibly contained in water was during the course 

 of that protracted discussion studied by Pasteur with the assist- 

 ance of M. Joubert, Professor of Physics at the College Eollin. 

 Such germs were to be found even in the distilled water of labo- 

 ratories ; it was sufficient that the water should be poured in a 

 thin stream through the air to become contaminated. Spring 

 water, if slowly filtered through a solid mass of ground, alone 

 contained no germs. 



There was also the question of the urine and that of the re- 

 cipient. The urine, collected by Dr. Bastian in a vase and 

 placed into a retort, neither of which had been put through a 

 flame, might contain spores of a bacillus called bacillus subtilis, 

 which offer a great resistance to the action of heat. Those 

 spores do not develop in notably acid liquids, but the liquid hav- 

 ing been neutralized or rendered slightly alkaline by the potash , 

 the development of germs took place. The thing therefore to 

 be done was to collect the urine in a vase and introduce it into 

 a retort both of which had been put through a flame. After 



