208 AMPHIMIXIS OR ESSENTIAL MEANING OF [XII. 



fertilization in the Metazoa is always associated with repro- 

 duction, but that the one process is not necessarily an ac- 

 companiment of the other, and that, as a matter of fact, the 

 conjugation of Infusoria has nothing to do with reproduction. 

 The majority of previous writers believed that conjugation 

 revived the exhausted power of multiplying by fission. Mau- 

 pas shows that this is not the case, that not only is fission 

 deferred for a comparatively long time after the occurrence 

 of conjugation, but that animals which have been prevented 

 from conjugating continue to divide for a considerable period. 



The view which Maupas thus overthrows was never a 

 legitimate inference from accurate scientific observations, but 

 was one of those traditional conceptions which gain acceptance 

 after having been consciously or unconsciously derived from 

 other similar conceptions. The supposed vitalizing force of fer- 

 tilization was looked upon, for a long period of time, as the 

 condition of all development and reproduction. The opposing 

 facts were not at first strong enough to shake the foundation of 

 this idea, and the preconceived notion that the magic of fertiliza- 

 tion was the sole vitaHzing life-maintaining principle, endured, 

 while the facts of asexual and parthenogenetic reproduction 

 were, by some evasion or other— the influence of fertilization 

 extending over many generations, (S:c. — forced into the Pro- 

 crustean bed of the received fundamental conceptions. 



Even Maupas remains half buried in these old ideas. 

 Although he has rightly recognized that fertilization and re- 

 production are two entirely different and even antagonistic 

 processes, that they may be connected, as in the Metazoa, or 

 disconnected, as in the Protozoa, he still holds to the old 

 view of the vitalizing influence of amphimixis; he speaks of 

 it as a 'rajeunissement karyogamique,' and declares it to be a 

 means for the kindling afresh of that life which would, without it, 

 waste away into death. He quite forgets that this view wholly 

 depends upon the facts of fertilization among Metazoa, viz. in the 

 inseparable connection between fertilization and reproduction 

 which we find in these animals, but which he himself has shown 

 to he absent from the Protozoa. He overlooks the consequence 

 of this absence, viz. the proof that in this case ^ post hoc' is not 

 ^propter hoc^ and keeps to the old standpoint which was a 

 right one only so long as we were obliged to believe that new 



