DOMAIN OF EVOLUTIONARY HYPOTHESIS 85 



anywhere became capable of providing a habitat for 

 organic existence. 1 



This idea owes its origin to the ' impossibility that 

 lifeless material can pass into living/ 3 The investiga- 

 tors named do not therefore rank with our opponents : 

 their opinion implies rather ' a fundamental difference 

 between living and inorganic substance and a duality 

 in infinitum.' 3 



Such attempts at explanation have naturally not 

 met with much approbation because they belong to the 

 ' merry realm of speculation ' and are absolutely 

 beyond proof. 



Now and again the belief arises in the doctrine of 

 ' spontaneous generation/ the most acceptable attempt 

 at explanation of the origin of life on our planet. This 

 implies the spontaneous generation of living bodies 

 (organisms) from the ordinary (inorganic) materials 

 as the effect of ordinary chemical and physical powers, 

 either under special or also under the conditions ruling 

 at the present time. 4 As a rule ' special ' environmental 

 conditions are demanded which do not now present them- 

 selves, but no details of such specializations are given. 



1 Reinke : Die Welt als Tat, Berlin, 1905, p. 344. See also E. v. Hart- 

 mann : Das Problem des Lebens, Bad Sachsa i/Harz, 1906, p. 178 ; and 

 H. Muckermann : Grundriss der Biologic, I, Freiburg, 1909, p. 144. 



2 0. Hertwig : Attg. Biologic, p. 272. 



3 Reinke : Die Welt als Tat, Berlin, 1905, p. 345. 



4 According to Naegeli (Mechan.-Physiol. TheoriederAbstammungslehre, 

 87) this generation occurs in the ' warmer seasons ' even to-day and in 

 our own regions, principally, however, ' in the warmer climates, and in the 

 old primeval time after the cooling of the earth down to breeding heat.' 

 Usually the possibility of spontaneous generation is only attributed to the 

 earliest times. 



