62 THOUGHTS ON NATURAL PHILOSOPHY. 



the summer, an enormous quantity of living sub- 

 stance has been formed out of the purely inorganic 

 substances of the environment, and when winter 

 comes, almost the whole quantity of this living 

 substance returns again to simpler inorganic com- 

 pounds. It is here seen how inseparably related are 

 inorganic and organic nature, how living substance 

 is originating continually from lifeless substance and 

 is continually being decomposed again into lifeless 

 substances. Nageli ('84), one of the most talented 

 botanists, says rightly: ' One fact that in organisms 

 inorganic substance becomes organic substance, and 

 that the organic returns completely to the inorganic 

 is sufficient to enable us to deduce by means of 

 the law of causation the spontaneous origin of 

 organic nature from inorganic.' If in the physical 

 world all things stand in casual connection with one 

 another, if all phenomena proceed along natural 

 paths, then organisms, which build themselves up 

 from and finally disintegrate into the substances of 

 which organic nature consists, must have originated 

 primitively from inorganic compounds. To deny 

 spontaneous generation is to proclaim a miracle." 

 (Verworn.) When we think of the beginning of 

 organic life we must not think primarily of carbonic 

 acid and ammonia; for they are the end of life, 

 not the beginning. The beginning lies rather in 

 *cyanogen. Hence the problem of the origin of 

 living substance culminates in the question: tHow 



* Cyanogen, see Addenda. 



t It may also possibly arise through the action of electricity in the 

 f jrm of lighting, under suitable conditions, as well as by the method 

 suggested by Pfluger. 



