THE DEVELOPMENT OP THE ANIMAL WORLD 



CHAPTER V 

 THE DEVELOPMENT OF THE ANIMAL WORLD 



BEFORE we begin to trace the growth of the tree of 

 animal life from the primitive " microbe " to the human 

 being it is necessary to say a few words on certain 

 controversies that divide scientific men in regard to 

 biological evolution. Of the fact of the derivation of the 

 higher species of animals from the lower, no zoologist in 

 England has now the slightest doubt, or would spend 

 five minutes in proving that general fact. There are, of 

 course, disputes as to the relationship of particular 

 groups of animals, but these will generally lie beyond 

 the limits of this small work, and will be respected. But 

 the general reader who only occasionally dips fnto 

 evolutionary literature will have a confused feeling that 

 there are still great and general controversies seething 

 in the zoological world, and he may be grateful for an 

 introductory page on the relations of Lamarck, Darwin, 

 Weismann, and De Vries (representing Mendelism or 

 Mutationism). 



For Lamarck, who worked in the faint dawn of 

 evolutionary science, the great agencies at work in 

 development were adaptation and heredity. These 

 agencies are thoroughly sound, but Lamarck applied 

 them in a way which most of our zoologists are not now 

 willing to accept. Let us take the development of wings 

 in the bat. A small early mammal with somewhat 

 webby fore-limbs has in this an advantage over its 

 rivals. As the web or skin extends, it can use it as 

 \vings and fly. Now Lamarck (while not explaining how 



