15 



their origin. The theory of spontaneous generation was thus kept 

 alive for a century. 



In 1860, the French Academy of Sciences offered a prize to 

 anyone who would provide a decisive experimental result to halt the 

 old controversy. Louis Pasteur's experiments of the 1860s with the 

 swan-neck glass flasks are part of our scientific heritage (fig. II-l). 

 Pasteur announced his results to the French in the following words: 

 "Life is a germ, and a germ is life. Never will the doctrine of spon- 

 taneous generation recover from this mortal blow." 



About the same time there came a clear insight from the field of 

 organic chemistry. Perhaps it is premature to use that term, for in the 

 mid-nineteenth century the chemistry of carbon compounds had not 

 yet come of age. The great Berzelius in 1815 had argued that organic 

 compounds were produced from the elements by laws differing from 

 those governing the formation of inorganic molecules. According to 

 him, organic compounds were produced under the influence of an 

 essential vital force and therefore could not be produced artificially. 

 But Wohler's classic experiment of 1828, in which a product of ani- 

 mal metabolism, urea, was produced by the heating of ammonium 

 cyanate, weakened the sharp distinction between the organic and 



Figure II-l- In the 1860s, Louis Pasteur showed that life did not arise spon- 

 taneously. The intact swan-neck flask (a) remained sterile, while the one with 

 the broken neck (b) did not. 



