THE GENERAL CONDITIONS OF LIFE 307 



constituents of proteid. In other words, life is derived from iire, 

 and its fundamental conditions were laid down at a time when the 

 earth was still an incandescent ball." 



" If now we consider the immeasurably long time during which 

 the cooling of the earth's surface dragged itself slowly along, 

 cyanogen and the compounds that contain cyanogen- and hydro- 

 carbon-substances had time and opportunity to indulge extensively 

 their great tendency toward transformation and polymerisation 

 and to pass over with the aid of oxygen, and later of water and 

 salts, into that self-destructive proteid, living matter." 



Pfliiger thereupon summarises his ideas in the following 

 sentences : " Accordingly, I would say that the first proteid to 

 arise was living matter, endowed in all its radicals with the 

 property of vigorously attracting similar constituents, adding 

 them chemically to its molecule, and thus growing ad infinitum. 

 According to this idea, living proteid does not need to have a 

 constant molecular weight ; it is a huge molecule undergoing 

 constant, never-ending formation and constant decomposition, and 

 probably behaves toward the usual chemical molecules as the sun 

 behaves toward small meteors." 



" In the plant, living proteid simply continues to do what it has 

 always done since its origin, i.e., regenerate or grow; wherefore I 

 believe that all proteid existing in the world to-day was derived 

 directly from the first proteid. Therefore, I am doubtful 

 about the occurrence of spontaneous generation at the present 

 Lime. Comparative biology also points unmistakably to the idea 

 that all living substance has taken its origin from a single root 

 only." 



B. CRITICAL 



1. Eternity or Beginning of Living Suhstancc 



Among the ideas regarding the derivation of life upon the earth 

 that are contained in the theories just presented, two notions 

 stand in sharp contrast to one another. This contrast finds 

 expression in the alternative already set forth by Helmholtz ^ : 

 " Organic life either has begun to exist at some one time or has existed 

 from eternity." The former notion lies at the foundation of the 

 doctrine of spontaneous generation, the latter at that of the 

 theory of cosmozoa, and in a certain sense at the basis of Preyer's 

 theory also. Evidently the two notions are mutually exclusive. If 

 one is accepted, the other must be rejected. To which of the two 

 shall we adhere ? 



We will test first the theory of cosmozoa. According to it life has 

 never originated, but has existed in the uni\erse from eternity, and 



' Loc. eit. 



