98 FLOATING-MATTER OF THE AIR. 



perfectly clear. The same remark applies to turnip- 

 infusions, some of which liave been found as clear as dis- 

 tilled water, while in general a slight opalescence is not 

 to be got rid of by filtering. 



These later experiments are quite in harmony with 

 the earlier ones. Not a single flask of this multitude 

 manifests the deportment alleged to be a matter of 

 common observation.' If the power of spontaneous 

 generation be a scientific verity, surely amid opportu- 

 nities so mviltiplied and various it must have exerted 

 itself. That the infusions employed were not 'de- 

 graded ' by the boiling so as to be incapable of sup- 

 porting life, was proved by the fact that exposed tubes 

 containing the same infusions, treated in precisely the 

 same way, resolved themselves with the usual speed 

 into Bacterial swarms. 



§ 23. Conditions as to the Temperature and 

 Strength of Infusions. 



In connection with these experiments, I have sought, 

 to the best of my ability, to meet every condition and 

 requirement laid down by others as essential to success. 

 Witli regard to warmth, a temperature of 90° was 

 generally attainable in our laboratory, while on cer- 

 tain days of mild weather without, and in favourable 

 positions within, the temperature to which the infu- 

 sions were subjected reached over 100° Fahr. As 

 Dr. Bastian, however, had laid considerable stress on 

 warmth, though most of his results were obtained 

 with temperatures from 15° to 30° lower than mine,'^ I 



• This group of flasks was submitted to the inspection of the 

 Fellows of the Royal Society on the 13th of January, 1876. 



■^ Proc. Roy. Soc. vol. xxi. p. 130. Also ' Beginnings of Life,' 

 vol. i. p. 354. 



