INTRODUCTION. 3 



made to appear demonstrated ; and by considering 

 the difficulties, alone, an opposite result may be 

 obtained. Unfortunately most of our publications 

 take one of these two courses, and are, therefore, in 

 a measure unsatisfactory. It requires more exten- 

 sive reading and more careful balancing of evidence 

 than most readers are inclined to give, to perceive 

 the real force of the arguments. 



What is Evolution ? 



It is necessary at the outset to inquire into the 

 meaning of the term evolution. So varied has been 

 the discussion, and so numerous the senses in 

 which the word is used, that to say that one accepts 

 evolution conveys no adequate idea, for it may 

 mean much or it may mean almost nothing. When 

 first used, the word had a very different significance 

 from that which now is attached to it. It was 

 believed by certain naturalists of the last century 

 that there then existed in the egg an individual pre- 

 cisely like the adult, except that it was too small to 

 be visible. The development of the egg was simply 

 the growth of this minute individual, a growth pre- 

 cisely similar to that taking place in animals after 

 birth. This theory was called evolution. Very 

 soon, however, it was disproved, for a few observa- 

 tions served to show that no such simple growth 

 took place. But the word evolution was still re- 

 tained to apply to development in general, and thus 

 for a long time it simply referred to the develop- 

 ment of the individual from the egg. But slowly 

 the word came to be applied to a different series of 



