DISCUSSION WITH BASTIAN 115 



or a little alkalin, and if I put it, furthermore, not in 

 one of your ovens where it is not sufficiently hot, but at 

 50 C., this same flask of urine which remains sterile in 

 your hands, becomes clouded at the end of 9 or 10 hours 

 and swarms with bacteria. From whence can they 

 come, if not from a spontaneous generation?" 



Repeated immediately in the laboratory of Pasteur, 

 the experiment was successful. It is, in reality, very 

 exact, but what must we conclude from it? Pasteur 

 could not interpret it as Bastian did. He acknowledged 

 that the germs were there: but whence did they come? 

 In this investigation, Pasteur beat about the bush for a 

 long time, and during this time his ideas, like his discus- 

 sion with Bastian, were rather confused. I will simplify 

 my exposition considerably by saying that these germs 

 for which Pasteur demanded an explanation from ex- 

 perimentation, could be derived from three sources, 

 unsuspected up to that time: first from the solution of 

 potash; second from the boiled urine; and third from the 

 walls of the flask. It was, we see, the introduction of 

 solids and liquids, as conveyors of germs, into a question 

 where up to that time, the ah*, chiefly, had been incrimi- 

 nated. Let us examine separately the three sources 

 which we have just enumerated. 



The solution of boiled potash may contain germs, and 

 yet that seems surprising when one thinks that this 

 solution is made with a piece of fused potash which, in a 

 solid state, actively attacks animal membranes and 

 destroys everything living. Therefore, it is not this 

 which can carry the germs, and, in reality, if we repeat 

 the experiment of Bastian, replacing the solution of boiled 

 potash with an equivalent fragment of fused potash, 

 the experiment does not succeed, and the urine con- 

 tinues to be sterile. Then it is the water that conveys 

 the germs, and in studying this subject Pasteur and 



