THE GENERAL CONDITIONS OF LIFE 319 



Nature itself has no goal to strive for, its method is eternal 

 development, i.e., change without end. 



To draw, now, the final conclusions from the above discussion, 

 the fact stands out clearly and distinctly that life from its 

 beginning on has been dependent upon the external conditions of 

 the earth's surface. In a mathematical sense, life is a function of 

 the earth's development. Living substance could not exist while 

 the earth was a molten sphere without a solid, cool crust ; it 

 was obliged to appear with the same inevitable necessity as a 

 chemical combination, when the necessary conditions were given ; 

 and it was obliged to change its form and its composition in the 

 same measure as the external conditions of life changed in the 

 course of the earth's development. It is only a portion of the 

 earth's matter. The combination of this matter into living sub- 

 stance was as much the necessary product of the earth's develop- 

 ment as was the origin of water. It was an inevitable result of 

 the progressive cooling of the masses that formed the earth's 

 crust. Likewise, the chemical, phj'sical and morphological 

 characteristics of existing living substance are the necessary result 

 of the influence of the external conditions of life upon the internal 

 relations of past living substance. Internal and external vital 

 conditions are inseparably correlated, and the expression of this 

 correlation is life. 



III. The History of Death 



Our consideration of vital conditions culminated in the fact that 

 vital phenomena not only can exist, but must appear with the 

 same inevitable necessity as every other natural phenomenon, 

 when a certain complex of conditions is fulfilled. If these conditions 

 are wanting, life is wanting. 



The appearance of life upon the earth was one consequence of 

 this fact. Another consequence, which is now to be considered, 

 was the development of death. 



A. THE PHENOMENA OF NECROBIOSIS 



If one or more of the special vital conditions under which an 

 organism exists fail, vital phenomena cease, life comes to a stand- 

 still. Excepting the few cases of apparent death, this standstill 

 is always real death. But, as has already been seen,^ death never 

 appears instantaneously. There is no sharp limit separating life and 

 death, there is rather a gradual transition between them ; in other 

 words, death undergoes development. Normal life upon the one 



1 Cf. p. 134 



