I/O THE SUCCESSION OF ANIMAL FORMS 



away in the almost illimitable depths of past time, and we are 

 ready to despair of ever reaching, by any process of discovery, 

 to its first steps of progress. At what time did life begin ? In 

 what form did dead matter first assume or receive those 

 mysterious functions of growth, reproduction and sensation ? 

 Only when we picture to ourselves an absolutely lifeless world, 

 destitute of any germ of life or organization, can we realize 

 the magnitude of these questions, and perceive how necessary 

 it is to limit their scope if we would hope for any satisfactory 

 answer. 



We may here dismiss altogether that form in which these 

 questions present themselves to the biologist, when he experi- 

 ments as to the evolution of living forms from dead liquids or 

 solids attacking the unsolved problem of spontaneous genera- 

 tion. Nor need we enter on the vast field of discussion as to 

 modern animals and plants opened up by Darwin and others. 

 I shall confine myself altogether to that historical or palseonto- 

 logical aspect in which life presents itself when we study the 

 fossil remains entombed in the sediments of the earth's crust, 

 and which will enable me at least to show why some students 

 of fossils hesitate to give in their adhesion to any of the cur- 

 rent notions as to the origin of species. It will also be desir- 

 able to avoid, as far as possible, the use of the term "evolution," 

 as this has recently been employed in so many senses, whether 

 of development or causation, as to have become nearly useless 

 for any scientific purpose ; and that when I speak of creation 

 of species, the term is to be understood not in the arbitrary 

 sense forced on it by some modern writers, but as indicating 

 the continuous introduction of new forms of life under definite 

 laws, but by a power not emanating from within themselves, 

 nor from the inanimate nature surrounding them.^ 



^ The terms Derivation, Development and Causation have clear and 

 definite meanings, and it is preferable, wherever possible, to use one or other 

 of these. 



