354 THE BEGINNINGS OF LIFE. 



between 75-86F (23-29C), though occasionally it 

 has been even higher than this. Sometimes the flasks 

 have been exposed to the lower temperature and some- 

 times to the higher, and I suspect that a variation of 

 this kind may perhaps be more favourable for the 

 production of evolutional changes than maintenance at 

 a constant temperature. 



In detailing the results of the following experiments, 

 I shall not enter into any minute description of the 

 organisms found. The main object throughout has 

 been to obtain evidence on the subject as to whether a 

 de no*vo evolution of living things could or could not 

 take place. Occasionally only small portions of the 

 experimental fluids have been examined. If, for 

 instance, what was found in the first few drops of the 

 fluid left no doubt in my mind as to the nature and 

 abundance of some living things contained therein, the 

 remaining portions of the fluid were frequently not 

 scrutinized. 



Seeing that M. Pasteur and others admit that organ- 

 isms are to be met with in neutral or slightly alkaline 

 fluids, treated in the manner adopted by Schwann ', 

 I will only mention the fact that neutral solutions of 

 hay, mutton, beef, and other substances have also 

 readily yielded organisms in the course of a few days 

 when treated in the manner just described. With 

 respect to acid solutions, however, M. Pasteur's verdict 



1 M. Pasteur's explanation of this fact will be subsequently considered. 



