PAET II 



THE CAUSES OF THE PERSISTENCE OF ORGANS 

 OR INSTITUTIONS WITHOUT FUNCTION 



CHAPTEK I 



SURVIVAL OF ORGANS 



WE have shown how and why organs may become 

 rudimentary and tend to disappear. In many 

 cases the disappearance is complete ; and the organ 

 may not even reappear temporarily in the course of 

 the individual development. This disappearance 

 is, however, by no means universal. Even apart 

 from the phenomena of recapitulation, rudimentary 

 organs may persist in the adult, and sometimes, even 

 although organs have ceased to be functional, they 

 persist without degenerating. We have now to con- 

 sider why in such cases degenerative evolution does 

 not result in complete obliteration of such organs. 



1. Unfiinctional organs that are not rudimentary. 



ABSENCE OF VARIATIONS. There are some plants 

 such as Ficaria x ranunculo'ides and Lysimachia 



i Lysimachia Nummularia occasionally produce seeds in some 

 valleys of the Pyrenees, and Errera has shown us specimens grown 

 from'seeds coming from the shores of the lake of Quatre-Cantons, 

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