PALAEONTOLOGY. 379 



Darwin's theory to zoological classification, and it exerted 

 a widespread influence both in extending the knowledge of 

 Darwin's leading principles and in demonstrating the great 

 superiority of a scheme of classification based upon these 

 principles over the many artificial schemes which had been 

 previously proposed on the basis of recurrent earth cata- 

 strophes, or on that of repeated exhibitions of the creative 

 force and the working of inscrutable laws. 



A decade after the publication of the Origin of Species^ 

 Darwin's theory of descent was almost universally accepted 

 as the most natural basis of classification in all the domains 

 of the science of animal organisms. Darwin's conception of 

 the origin of species could not fail to enhance the interest of 

 palaeontology. That study was realised to be no longer merely 

 descriptive and comparative, or the means of bringing useful 

 material to the sciences of botany and zoology, but a branch 

 of knowledge to be studied for its own intrinsic interest. 



The greatest likelihood of solving some of the obscure 

 problems of the origin and extinction of species lay with the 

 palaeontologist, since the rich material at his command, ex- 

 tending through many successive ages, comprised the record 

 of the incoming and outgoing of countless types of life. The 

 origin, geological development, gradual modification, differ- 

 entiation, improvement or degeneration of the individual 

 groups of the animal and plant kingdom, the genealogical 

 relations of the primaeval and recent organisms, the phylogeny 

 of the plant and animal world, the relations between the 

 developmental history (ontogeny) of the single individual, 

 and the history of descent (phylogeny) of the family, order, 

 and class to which the individual belongs, are questions which 

 can be answered either exclusively by palaeontology or only 

 with its assistance. 



With Darwin begins the modern period of palaeontological 

 research. Numerous and important evidences were brought 

 forward in favour of the doctrine of descent. The continuous 

 series of forms, which can be followed through several strati- 

 graphical horizons and formations with greater and less 

 variations, the occurrence of mixed and embryonic types, 

 the parallels of ontogeny with the chronological succession 

 of related fossil forms (biogenetic principle of Haeckel), the 

 similarity in the general impress of the fossil floras and faunas 

 next each other in age, the agreement in the geographical 



