136 THE EVOLUTION OF LIVING BEINGS. 



Lycopsida Lycopodiales. 



Filicales. 



T., ., Pteridospermeae. 



Pteropsida 



Gymnospermeae. 



Angiospermeae. 



Of these three great divisions the two first are ex- 

 tinct, with the exception of a few Equisetaceae, Psilo- 

 taceae and Lycopadiaceae ; of the Pteropsida the Pte- 

 ridospermeae are extinct, Gymnospermeae on the way 

 to extinction, so that only the Filicales and the An- 

 giosperms remain, of which the latter alone, are flou- 

 rishing. 



A formation of new classes is not in action at the pre- 

 sent moment, so that it is illegitimate to claim, that one 

 who wants to explain evolution, must demonstrate how 

 such a formation of new classes goes on. 



One can 't demonstrate something which does not 

 happen, at the time one is living; we must conclude to 

 the way of the origin of new classes by analogy, and we 

 have done so, by comparing it with what happens after 

 crossing two Linneons. What happens there, is demon- 

 strable and we have demonstrated it. 



Whether new classes will in future be formed again 

 on our globe, or whether we assist at the last trial of 

 life to maintain itself on our globe, in other words 

 whether we are living at the beginning of the period of 

 extinction of the latest born classes, we of course know 

 not. 



