220 FOOTNOTES FROM 



quantity of seeds in the ground, than when he leaves the 

 chance of a crop to the scattering self-sown wheat of the 

 previous autumn. Indeed, the most prolonged and closest 

 observations, and the most carefully-conducted experi- 

 ments, have not led to the proof of a single instance of 

 spontaneous or equivocal generation, even of one of the 

 simplest of all living things ; but, on the contrary, they 

 all lead farther and farther from, or entirely disprove it. 

 F. Schulze, of Berlin, performed an experiment to test 

 the possibility of equivocal generation, under the play of 

 the indispensable conditions of life, free from access to 

 any pre-existing vegetable or animal germs. " A glass 

 vessel, half filled with a mixture of various dead vege- 

 table and animal substances in water, was heated to 

 212 Fahr., so as to destroy any living bodies which 

 might exist within. To the vessel was then adapted a 

 pair of Liebig's bulbs, one of which contained sulphuric 

 acid, the other a solution of potassa, and through these 

 only could the exterior air have access to its interior. 

 The apparatus was then placed in a window, where it 

 received the full influence of light, and the necessary 

 temperature for the production of life. The air within 

 the vessel was daily renewed from May till August, by 

 blowing through the sulphuric acid, from which it could 

 suffer no change, except to be deprived of moisture and 

 organic particles. During all that time not even the 

 simplest animal or vegetable forms were produced ; 

 while in an open vessel, containing the same mixture in 

 the same situation, there were observed on the following 

 day numerous vibrios and monads, and to these were 

 soon added larger animaculee." This interesting experi- 



