636 THE BEGINNINGS OF LIFE. 



These myriads of lowest forms of life, multiplying only 

 by processes of fission and gemmation, constitute an 

 inextricably tangled plexus of more or less convertible 

 animal and vegetal forms, which — though often reap- 

 pearing — are for the most part evanescent and transi- 

 tory states, either of comparatively new-born living 

 matter, or of portions of matter which have become 

 individualized by heterogenetic processes occurring in 

 the substance of the higher forms of life. But how- 

 soever derived, they constitute a vast assemblage of 

 ' Ephemeromorphs,' amongst which Heterogenesis oc- 

 curs almost as frequently as Homogenesis. 



Gradually, however, the first traces of those processes 

 of ^ conjugation ' and of internal gemmation begin to 

 manifest themselves, which subsequently become per- 

 fected into ^sexual' modes of reproduction. 



Connected series of transformations tend to occur, 

 in the last of which by a sexual reproductive act a 

 fecundated germ is produced, which in its development 

 goes through a similar series of transformations ; or 

 else animal organisms of a decidedly sexual type are 

 more directly formed by the 'vital crystallization' of 

 larger and more specialized egg-like aggregates of living 

 matter, which have been elaborated during the life of 

 some lower vegetal organism. 



But when animal or vegetal organisms manifesting 

 that cyclical homogenesis which is known as 'alternate 

 generation,' appear upon the scene, and with them 

 those simpler allies (formed from large germs) which 



