PREFACE 



Several years ago Lord Rosebery founded, in 

 the University of Edinburgh, a lectureship on ' The 

 Philosophy of Natural History," and I was invited by 

 the Senatus to deliver the lectures. This invitation 

 I accepted, and subsequently constituted the material 

 of my lectures the foundation of another course, which 

 was given in the Royal Institution, under the title 

 " Before and after Darwin.'' Here the course extended 

 over three years — namely from iHHcS to 1890. The 

 lectures for 1888 were devoted to the history of biology 

 from the earliest recorded times till the publication of 

 the " Origin of Species " in 1 859 ; the lectures for 

 1889 dealt with the theory of organic evolution up to 

 the date of Mr. Darwins death, in 1882 ; while 

 those of the third }'ear discussed the further develop- 

 ments of this theory from that date till the close of 

 the course in 1890. 



It is from these two courses — which resembled each 

 other in comprising between thirty and forty lectures 

 but differed largely in other respects — that the pre- 

 sent treatise has grown. Seeing, however, that it has 



