344 THE RECAPITULATION THEORY 



disadvantageous, and may lead to destruction rather 

 than to survival. It has happened more than once 

 in the history of the world, and in more than one 

 group of animals, that gigantic stature has been 

 attained immediately before extinction of the group, 

 a final and tremendous effort to secure survival, but 

 a despairing and unsuccessful one. The Ichthyo- 

 sauri, Plesiosauri, and other extinct reptilian groups, 

 the Moas, and the huge extinct Edentates, are well- 

 known examples, to which before long will be added 

 the elephants and the whales, and it may be iron- 

 clads as well. The whole question of the influence 

 of size is of the greatest possible interest and 

 importance, and it is greatly to be hoped that it 

 will not be permitted to remain in its present un- 

 certain and unsatisfactory condition. 



It may be suggested that Amphioxus is an 

 animal which has undergone reduction in size, and 

 that its structural simplicity may, like that of 

 Limapontia, be due in part at least to this reduc- 

 tion. Such evidence as we have tells against this 

 suggestion ; the first system to undergo degenera- 

 tion in consequence of a reduction in size is the 

 respiratory, and the respiratory organs of Amphioxus, 

 though very simple, are also for a vertebrate 

 unusually extensive. 



/\Ve have now considered the more important of 

 jhe Influences which are recognised as affecting 

 developmental history in such a way as to render 

 the recapitulation of ancestral stages less complete 

 than it might otherwise be, which tend to prevent 

 ontogeny from correctly repeating the phylogenetic 



