GENESIS. 



215 



Tineidw, parthenogenesis appears to be a normal process- 

 indeed, so far as is known, the only process ; for of some 

 species the males have never been found. 



A general conception of the relations among the different 

 modes of Genesis, thus briefly described, will be best given 

 by the following tabular statement. 



Homogenesis, which is Gamogenesis . 



Genesis is ■ 



r Gamogenesis 

 alternating 



.Hetcrogenesis.whichisJ 



with 



|_ Agamogenesis 



Oviparous 



or 

 Ovo-viviparoua 



or 

 .Viviparous 



'Parthenogenesis 



or 

 Pseudo-parthenogenesis 

 or _ /"Internal 

 . Metagenesis -j or 



[ External 



This, like all other classifications of such phenomena, pre- 

 sents anomalies. It may be justly objected, that the processes 

 here grouped under the head agamogenesis, are the same as 

 those before grouped under the head of discontinuous develop- 

 ment (§ 50) : thus making development and genesis partially 

 coincident. Doubtless it seems awkward that what are from 

 one point of view considered as structural changes, are from 

 another point of view considered as modes of mvdtiplication.* 



* Prof. Huxley avoids this difficulty by making every kind of Genesis a mode 

 of development. His classification, which suggested the one given above, is ar 

 follows : — 



Development 



Continuous 



Growth 



[ Metamorphosis 



i Metagenesis 

 Parthenogene 

 Gamogenesis 



