734 General and Applied Biology 



Theories for the Origin of Life on the Earth 



1 . Cosmozoa Theory. — This theory suggests that, because of the com- 

 plexity of hving matter and the cstabhshment of biogenesis, hfe came to 

 the earth from some other part of the universe. It was assumed that 

 certain heavenly bodies of the universe have always been the abode of 

 life and that life in a latent state was carried to the earth from them by 

 small particles of those planets on which it existed at that time. This 

 does not explain the real origin of life at its very beginning. This theory 

 is based on two unproved assumptions: (1) that life exists or has 

 existed elsewhere in the universe and (2) that life can be maintained 

 during the interstellar voyage to the earth. 



We have proof that certain present-day organisms under the influence 

 of unfavorable environments can resist dryness, heat, cold, etc., although 

 this does not prove that their remote ancestors may have had similar 

 or greater properties of this type. These would be necessary to resist 

 in transit such factors as the effects of light waves, extremely low tem- 

 peratures, absence of water vapor in cosmic space, radiations, etc. 



2. Pfliiger's Theory. — Pfliiger assumed that the earth was originally 

 a superheated, incandescent mass from which arose a combination of 

 carbon and nitrogen atoms to form cyanogen (CN). This union can 

 occur only at high temperatures and takes up a large amount of energy 

 in the form of heat which contributes energy to the organic protein com- 

 pounds of which living substances (protoplasm) are composed. 



3. Moore's Theory. — Moore suggests that life arose under suitable 

 conditions from the inorganic elements of a cooling earth by a process 

 of continuous complexification; that is, matter in general will tend to 

 assume more and more complex forms in labile equilibrium. He sug- 

 gests that the process of complexification is inherent in all matter and 

 that, when a sufficiently complex stage is once reached in this evolution- 

 ary process, life invariably will be an attribute. Atoms, molecules, 

 oxides, carbonates, colloids, and then living organisms arise as a result 

 of these successive operations. This theory attempts to bridge the gap 

 between nonliving and living substances. 



4. Allen's Theory. — Allen suggests that at a time when the physical 

 conditions of the earth were much as they are now some reactions as 

 the following occurred: Energy coming from the sun was absorbed by 

 the iron in damp earth or water and acted on certain raw materials in 

 such a way as to dissociate and rearrange the atoms. This interaction 

 between the nitrogen, carbon, hydrogen, oxygen, and sulfur resulted in 



