12 BIOLOGY 



Spontaneous Generation or Abiogenesis. This idea of spon- 

 taneous generation, or abiogenesis (Gr. a = without + bios = 

 life + genesis = generation), has been before the scientific world 

 for centuries. The ancients in the time of Aristotle, and for 

 centuries later, had no especial question in regard to the matter, 

 and took it for granted that living things did come from in- 

 animate matter. Virgil tells us of bees coming from the flesh 

 of bullocks; Ovid recounts that slime begets frogs; and many 

 centuries afterwards, we read that water produces fishes and 

 that mice can come from old rags. Although to-day these 

 ideas seem nonsensical, once they appeared perfectly logical. 



Experiments of Redi. This idea that life could come from 

 non-living matter was held without question during the earlier 

 centuries, and indeed until about the 17th century. In 1680 

 an Italian named Redi made an observation which led him to 

 what was at that time a rather startling conclusion. It had pre- 

 viously been observed that fly maggots made their appearance 

 in decaying flesh, and it was taken for granted that they devel- 

 oped spontaneously. Redi noticed flies hovering over meat, 

 and demonstrated by experiments that if the flies were kept 

 away by simply tying paper over a bottle containing the meat, 

 maggots could never develop in it. A little further study 

 proved that the flies laid eggs on the meat which developed 

 into fly maggots. From this observation he drew the far- 

 reaching conclusion that spontaneous generation did not occur 

 and that all living things came from living ancestors. 



This conclusion started a dispute which lasted for two cen- 

 turies and was not fully settled until about 1875. For the 

 conclusion of Redi, that all living things came from living 

 ancestors, was vigorously disputed by the adherents of the old 

 idea that life could arise spontaneously. Many ingenious 

 experiments were devised to settle the question. It did not 

 take long to prove that so far as the larger animals and plants 

 were concerned, the conclusion of Redi was correct. But just 

 at this time the newly invented microscope was beginning to 



