GENERAL ADAPTATION 27 



in their architecture and functions, the brain and 

 its function reflect the same Nature, and an intelli- 

 gent man is one whose brain reproduces with the 

 greatest accuracy the series of external phenomena. 

 Intelligence is the sublimation of natural laws. 

 Thus we say that Nature is the inheritance of 

 humanity, and therefore miseries and egoisms are 

 absurd, through an error in the social organisation 

 when it severs itself from natural laws. 



Frogs and tadpoles are a surprising case of the 

 rapidity of adaptation. These animals, when they 

 are young, live in the water and breathe through 

 their gills ; then, as adults, they live on terra 

 firma their gills get atrophied and they acquire 

 pulmonary respiration. The metamorphosis of the 

 frog, by the disappearance of its tail and the 

 evolution of legs, is very curious and instructive, 

 as this species of embryology, which takes place 

 under the eyes of the observer, shows also its 

 phylogeny ; for its primitive form of a fish, as well 

 as its respiration by the gills, are proofs of the 

 transition of fishes into batrachi. It is a pheno- 

 menon in which man sees evolution in the very act, 

 when the aquatic vertebrata are changed into 

 terrestrial vertebrata. 



Some years ago the axolotl of Mexico (Siredon 

 pisciformis), very like the triton, excited great 



