IX THE HISTOKY AND SCOPE OF ZOOLOGY 301 



were not new but are to be found in some of the 

 ancient Greek philosophers, yet now for the first time 

 they could be considered with a sufficient knowledge 

 and certainty as to the facts, due to the careful observa- 

 tion of the two preceding centuries. The science of 

 Geology came into existence, and the whole panorama 

 of successive stages of the earth's history, each with 

 its distinct population of strange animals and plants, 

 unlike those of the present day and simpler in propor- 

 tion as they recede into the past, was revealed by Cuvier, 

 Agassiz, and others. The history of the crust of the 

 earth was explained by Lyell as due to a process of 

 slow development, in order to effect which he called 

 in no cataclysmic agencies, no mysterious forces differ- 

 ing from those operating at the present day. Thus 

 he carried on the narrative of orderly development 

 from the point at which it was left by Kant and 

 Laplace, explaining by reference to the ascertained 

 laws of physics and chemistry the configuration of the 

 earth, its mountains and seas, its igneous and its 

 stratified rocks, just as the astronomers had explained 

 by those same laws the evolution of the sun and planets 

 from diffused gaseous matter of high temperature. 



The suggestion that living things must also be 

 included in this great development was obvious. 

 They had been so included by poet-philosophers in 

 past ages ; they were so included by many a simple- 

 minded student of nature who, watching the growth 

 of the tree from the seed, formed a true but unverified 

 inference in favour of a general process of growth and 

 development of all things from simpler beginnings. 



