HISTORY OF ZOOLOGY. 23 



Lyell. — In the same year in which Cuvier obtained his victory 

 over Geoffrey St. Hilaire, his theory of the succession of numerous 

 animal worlds upon the globe received its first destructive blow. 

 Cuvier's cataclysm theory had two sides, a geological and a 

 biological. Cuvier denied the continuity of the various terrestrial 

 periods, as well as the continuity of the fauna and flora belonging 

 to them. In 1830-32 appeared the "Principles of Geology" by 

 Lyell, an epoch-making work, which, in the realm of geology, 

 completely set aside the cataclysm theory. Lyell proved that the 

 supposition of violent revolutions on the earth was not necessary 

 in order to explain the changes of the earth's surface and the 

 superjiosition of its strata; that rather the constantly acting 

 forces, elevations and depressions, the erosive action of water, be 

 it as ebb and flow of the tide, as rain, snow, or ice, or as the flow 

 of rivers and brooks rusliing as torrents towards the sea, are suffi- 

 cient to furnish a complete explanation. Very gradually in the 

 course of a vast space of time the earth's surface has changed, and 

 passed from one period into the next, and still at the present day 

 the constant process of change is going on. The continuity in the 

 geological history of the earth, here postulated for the first time, 

 has since then become one of the fundamental axioms of Geology; 

 on the other hand the discontinuity of living creatures, although 

 the geological support of this was frail, was for a long time 

 regarded as correct. 



Darwin. — It is the great merit of (Charles Darwin that he took 

 u}) tiie theory of descent anew after it had rested a decade, and 

 later brought it into general recognition. With this began tlie 

 most important period in the history of zoology, a period in which 

 tjie science not only made such an advance as never before, but 

 also Ijegan to obtain a permanent influence upon the general views 

 of men. 



Charles Darwin was born at Shrewsbury, Eng., in 180'.). After 

 studying at the universities of Edinburgh and Cambridge, he joined 

 as naturalist the English war-ship •' J-5eaglc." In its voyage from 

 1831 to 30 around the globe, Darwin recognized the peculiar 

 character of island fau.nas, particularly of the Galapagos Islamls, 

 and the remarkable geological succession of edentates in South 

 America; these facts formed for him the germ of his epoch-making 

 theory. Further results of this journey were his beautiful mono- 

 graph on the Cirripodia, and the classic investigation of coral-reefs. 

 After his return to England Darwin lived, entirely devoted to 

 scientific work, chiefly in tlie hamlet of Down, county Kent, up 



