HISTORY OF ZOOLOGY. I? 



often it may happen that one and the same function is pos- 

 sessed by organs anatomically different ; as, for example, 

 the respiration of vertebrates is carried on in fishes by gills, 

 in mammals by lungs. Conversely, anatomically similar 

 organs may have different functions, as the lungs of mam- 

 mals and the swim-bladder of fishes; similar organs may 

 also undergo a change of function from one group to an- 

 other; the hydrostatic apparatus of fishes has in the 

 mammals come to be the seat of respiration. Organs with 

 like functions, physiologically equal organs, are called 

 "analogous"; organs of like anatomical constitution, 

 anatomically equal organs, are called "homologous." It 

 should be regarded as the task of Comparative Anatomy 

 to discover in the various parts of animals those which are 

 homologous, i.e. those of equal anatomical value, and to 

 follow out the changes in them conditioned by a change of 

 function. 



Cuvier. The foremost representative of the compara- 

 tive anatomical tendency was Georges Dagobert Cuvier. 

 He was born in 1769 in the town of Mompelgardt (Mont- 

 beillard), then belonging to Wurtemberg, and obtained 

 his early training in the Karlschule at Stuttgart, where 

 through the influence of his teacher Kielmeyer, for whom 

 he always had great veneration, he was led to the study of 

 Comparative Anatomy. The opportunity of going to the 

 seashore which was offered to him as private instructor to 

 Count d'Hericy he employed for his epoch-making inves- 

 tigations upon the structure of mollusks. In I794> upon 

 the persuasion particularly of the man who afterwards be- 

 came his great opponent, Geoffroy St. Hilaire, he moved 

 to Paris, where he was made at first Professor of Natural 

 History in the central school and in the College of France, 

 later Professor of Comparative Anatomy in the Jardin des 

 Plantes. As a sign of the great regard in which Cuvier was 

 held, it should be noticed that he was repeatedly intrusted 

 with high educational positions and was made a French 

 peer. As such he died in 1832. 



Type Theory. Cuvier's investigations, apart from the 



