DEVELOPMENT OF SOIL BACTERIOLOGY 3 



make, gives to us a fairly accurate description of these minute 

 forms of life. However, it did not av^aken the world to even a 

 faint realization of the marvelous invisible forms of life which 

 were present in everything either as a blessing or as a curse. It 

 did, however, revive a discussion which waxed long and furious 

 as to whether life can spring spontaneously from dead matter or 

 is always the offspring of preexisting parents. 



Spontaneous Generation. — ^T^eories as to the origin of life 

 are as old as the human race. The doctrine of spontaneous gen- 

 eration is one of them. Many ancient writers fancifully por- 

 trayed the transforming of dead into living matter. The Greek 

 philosophers taught it. Aristotle said that "animals sometimes 

 arise in soil, in plants, or in other animals." Cardan (1501- 

 1576) wrote that water gives rise to fish and animals and is also 

 the cause of fermentation. 



As late as the sixteenth century a famous chemist and physicist, 

 van Helmont (1577- 1644), stated that mice can be generated 

 spontaneously by placing some dirty rags together with a few 

 grains of wheat or a piece of cheese in a dark place. Today the 

 same philosopher's method of producing scorpions is amusing. 

 "Scoop out a hole in a brick, put into it some sweet basil. Lay a 

 second brick upon the first so that the hole may be imperfectly cov- 

 ered. Expose the two bricks to the sun and at the end of a few 

 days the smell of the sweet basil, acting as a ferment, will change 

 the herb into a real scorpion." 



An Italian, Buonanni, tells of a wonderful change which he 

 claims to have witnessed. Rotten timbers which he rescued from 

 the sea produced worms; these gave rise to butterflies; and strang- 

 est of all, the butterflies became birds and flew away. 



Everyone took it as a self-evident fact that maggots originated 

 without parents from decomposing meat or cheese, until an Italian 

 poet and physician, Redi (1626-1695), took the simple precaution 

 of screening the mouth of jars containing meat so that flies could 

 not enter. Flies were attracted by the odor and deposited their 

 eggs on the gauze, and it was from these that the so-called 

 "worms" arose. 



