INTRODUCTION xxv 



the sensitive nerve-matter of the nervous system of animals, and 

 influence thought and all other nerve-action. 



Several branches of animals evolved from other animals which 

 were not stationary, but were changing. While changing, they in 

 turn were evolving others in various ' grooves ' of evolution. This 

 would account for the fact that although their descendants have 

 several characters in common with the ancestral stock, they are 

 nevertheless widely distinct in other characters ; and the characters 

 they mostly differed in were exactly those which depended on the 

 influences of surroundings for their development, and therefore 

 were greatly modified by them. 



There is another point about which zoologists seem to have no 

 doubt. 



Mr. Herbert Spencer i says : ' Zoologists are agreed that the 

 Whale has been evolved from a mammal which took to aquatic 

 habits, and that its disused hind-limbs have gradually disappeared.' 



Many others have also the same belief; for Mr. Hutchinson^ 

 says : ' Take for example the case of Whales and fishes ; the 

 original land mammal from which Whales are descended has in 

 course of time become so fish-like in appearance that even in these 

 modern days there' are some who yet speak of them as fishes ! 

 The shape of the Whale is fish-like; it has lost its hind-limbs 

 through disuse : it has changed its fore-limbs into paddles, which 

 have a certain fin-like aspect ; and its cousin, the Porpoise, has 

 developed a big triangular fin on the back.' 



All this derivation of water mammals from /aW mammals alone 

 may be true or untrue. In the words of Mr. Hutchinson : ' What 

 right has any one, however great his knowledge or his ability, to 

 dictate to Nature, and to say this or that is impossible?' 



* ' Rejoinder to Professor Weismann,' Contemporary Review, December 1893, P- 909- 

 ^ Creatures of OtTier Days, ■^. 131. 



