THE ORIGIN OF LIFE 



development of living matter from lifeless inorganic 

 carbon compounds) but relate to the formation of lower 

 organisms out of the putrid and decomposing organic 

 elements of higher organisms. In order to distinguish 

 these hypotheses from the totally different theory of 

 archigony, it is better to give them the name of sapro- 

 biosis (an earlier name was necrobiosis), which means 

 the birth of living from dead (nekron) or putrid {sapron) 

 organic matter. Saprobiosis is preferable, because nec- 

 robiosis is better used in a different sense, for the dead 

 organic parts which gradually bring about the death of 

 the living body (see p. io6). It was believed in ancient 

 times that lower organisms could arise from the dead 

 remains of higher organisms, such as fleas from manure, 

 lice from morbid pustules in the skin, moths from old 

 furs, and mussels from slime in the water. As these 

 stories were supported by the authority of Aristotle, and 

 on that account believed by St. Augustine and other 

 fathers, and reconciled with the faith, they were held 

 until the beginning of the eighteenth century. Even in 

 the year 17 13 the botanist Heucherus stated that the 

 green duck-weed (lemna) is only condensed grease from 

 the surface of foul standing water, and that water-cress 

 was formed from it in fresh running water. 



The first scientific refutation of these old stories was 

 made by the Italian physician, Francisco Redi, in 1674, 

 on the basis of very careful experiment: he was perse- 

 cuted for "unbelief" on that account. He showed that 

 all these animals arose from eggs that had been deposited 

 by female animals in dung, skin, fur, slime, etc. But at 

 that time the proof could not be extended to the tape- 

 worms, maw-worms, and other intestinal animals (en- 

 tozoa), which live inside other animals (in the bowels, 

 blood, brain, or liver). It was still believed that these 

 arise from diseased parts of the host-animals in which 

 they live, until about the middle of the nineteenth cen- 



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