252 



THE BEGINNINGS OF LIFE. 



and then, if new living things appear, we have no longer 

 to do with Heterogeny, but rather with Archebiosis. 



As to the various modes in which Heterogeny may 

 occur, we will say nothing more at present than may be 

 found in the following table. Numerous variations 

 will be subsequently described. 



r Archebiosis 



ORIGIN 



OF 



LIV/NG 

 THINGS. 



(primordial ori- 

 gination). 



From not-living ma- 

 terials. 



Heterogenetic. < 



f" i. From a portion of 

 the living matter of 

 a pre-existing or- 

 ganism (a) After its 

 death, (b) Before its 

 death. 



2. By a molecular me- 

 tamorphosis of the 

 matter of an entire 



Beproduction organism, 



(from pre-exist- - 3. By the metamor- 



ing living things). | phosis and fusion of 



many minute or- 

 ganisms. 



i. Indirect. Cases of 

 ' alternate" or cycli- 

 cal generation l . 



Homogenetic. ] 2. Direct. Continuous 

 development into 

 the likeness of its 

 parent. 



Having briefly indicated the nature of the problems 

 which require to be carefully discriminated from one 

 another, we will now, before enquiring into the possi- 

 bility of Archebiosis taking place in the present phase 

 of the earth's history, briefly enumerate some of the 

 different opinions which have been expressed by earlier 

 writers on the subject of c spontaneous generation.' 



1 These are the cases for which Mr. Herbert Spencer has appropriated 

 the term Heterogenesis' (see 'Principles of Biology,' vol. i. p. 210). The 

 above arrangement would, we think, meet his requirements. 



