xiv CONTENTS 



I. General Definition 



PAGE 



A theory of natural descent of existing species from earlier forms 



of organic life 38 



To be distinguished from monistic theories, especially of the 



materialistic type 40 



II. Early Views 



Previous to the time of Lamarck 45 



Lamarck's theory 47 



Darwin's success made possible by Lyell, Malthus, and others 50 



III. Darwin's Theory 



Its revolutionary effect 52 



Its reception 54 



Its nature and basis 55 



IV. Subsequent Discussions and Views 



Objections advanced against Darwin's theory by evolutionists 60 

 Weismann's argument against the transmission of acquired 



characters 65 



His germ-plasm theory 67 



Mendel's law 68 



The mutations theory 69 



Minor theories and outlook 72 



LECTURE III 



EVIDENCES AND LIMITATIONS 



What evidence ought to be required 75 



I. Summary of Evidence 



Its general nature 76 



1. Variation and heredity 77 



2. Homologous structures 78 



3. Gradation of organisms 79 



4. Embryology 80 



