THE STORY OF NINETEENTH-CENTURY SCIENCE 



given by experiment. Eecurring to a former belief, and 

 repeating some earlier experiments, the director of the 

 Museum of Natural History at Eouen, M. F. A. Pouchet, 

 reached the conclusion that organic beings are sponta- 

 neously generated about us constantly, in the familiar 

 processes of putrefaction, which were known to be due 

 to the agency of microscopic bacteria. But in 1862 

 Louis Pasteur proved that this seeming spontaneous 

 generation is in reality due to the existence of germs in 

 the air. Notwithstanding the conclusiveness of these 

 experiments, the claims of Pouchet were revived in Eng- 

 land ten years later by Professor Bastian ; but then the 

 experiments of John Tyndall, fully corroborating the 

 results of Pasteur, gave a final quietus to the claim of 

 "spontaneous generation" as hitherto formulated. 



There for the moment the matter rests. But the end 

 is not yet. Fauna and flora are here, and, thanks to 

 Lamarck and Wallace and Darwin, their development, 

 through the operation of those "secondary causes" 

 which we call laws of nature, has been proximally ex- 

 plained. The lowest forms of life have been linked with 

 the highest in unbroken chains of descent. Meantime, 

 through the efforts of chemists and biologists, the gap 

 between the inorganic and the organic worlds, which 

 once seemed almost infinite, has been constantly nar- 

 rowed. Already philosophy can throw a bridge across 

 that gap. But inductive science, which builds its own 

 bridges, has not yet spanned the chasm, small though it 

 appear. Until it shall have done so, the bridge of or- 

 ganic evolution is not quite complete : yet even as it 

 stands to-day it is the most stupendous scientific struct- 

 ure of our century. 



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