338 THE PHILOSOPHY OF BIOLOGY 



and distribution of organisms, and the quantity and 

 nature of their environment at any time, together 

 formed phases of this system. If there was a time when 

 life, as we know it, did not exist, then the materials 

 and the energies, which were antecedent to life when 

 it did appear, were also a phase of the system. On a 

 strictly mechanistic hypothesis there could be no 

 origin : there could only be a transformation of a 

 system which was already in existence. All that 

 exists to-day was given then. When, therefore, we 

 speak of the origin of life from non-living materials 

 we mean simply a transformation of those materials 

 and energies. 



There was a time, it is said, when life could not 

 exist on the earth. For the organism is essentially 

 that aggregate of chemical compounds which we call 

 protoplasm, and this cannot exist at temperatures 

 higher than loo' C, and it cannot function at tempera- 

 tures lower than o° C. It requires carbon dioxide, and 

 ammonia or nitrate, as the materials for its constructive 

 metabolism, and there was a time when these com- 

 pounds could not exist, for they must have been dis- 

 sociated by the heat of the gaseous nebula from which 

 our earth originated. The organism requires energy 

 in the form of solar radiation of a particular frequency 

 of vibration, and there was a time when the sun's 

 radiation was different from what it is now. Therefore 

 life did not exist then. Even if we believe that life came 

 to the earth as germs, which existed previously in outer 

 cosmic space, this belief does not solve the problem, 

 which simply becomes transferred from, our earth to 

 some other cosmic body. 



But life, as we know it, makes use of the materials 

 and the energies which are available to it in the con- 

 ditions in which it exists. The plant organism obtains 



