336 THE HISTORY OF BIOLOGY 



thus never has hoofs or flat molars, for they suit only herbivorous animals. 

 A practised naturalist should thus be able to determine from the shape of 

 one single, suitably selected part of the body the whole of the animal's 

 structure, habits, and place in the system. And in this system, therefore, 

 only such animals should be grouped together as fully conform to one 

 another, at least in the organs that are most essential to life. The creation 

 of a system based entirely upon such conformity in the organs henceforth 

 became one of the missions in life that Cuvier never let out of sight. For 

 the time being, however, he contented himself with a system of grouping 

 that differs from the old only in that the vertebrates and the invertebrates 

 are distinguished from one another, and also that the lowest animals are 

 grouped together under the name of Zoophyta — a name of which Lamarck 

 strongly disapproved. Otherwise Cuvier retained the variously composed 

 class Vermes, and he also made his anatomical comparisons cover the entire 

 animal kingdom all at once. In doing so, however, he is at the very outset 

 careful not to extend the comparisons in detail beyond what he can vouch 

 for — in sharp contrast to the audacity of both Vicq d'Azyr and Lamarck, 

 not to speak of Geoffroy Saint-Hilaire. 



His studies of fossils 

 During the succeeding period Cuvier applied his method to the special in- 

 vestigations into fishes and molluscs that have been previously mentioned, 

 but principally to mammals. Within this class he soon found himself engaged 

 in a special field of research, the study of fossil forms. As is well known, 

 Paris is situated in the centre of a calcareous district, in which the stone 

 used for building-material is particularly rich in fossils. These had already 

 attracted Buffon, for purposes of both observation and speculation; it was 

 on the basis of material gathered from this and other districts that he formed 

 his theory of the evolution of the earth and of the creatures living on it 

 (Part II, p. ii4). Cuvier, however, was the first to apply himself to a system- 

 atic exploration of the richly fossiliferous Paris area; with the assistance 

 of his friend Brogniart, he organized systematic excavations, in the course 

 of which the location of the fossils was closely observed and the animal 

 remains scattered about in each place were noted as carefully as possible. 

 After this Cuvier began to apply his correlation theory to fossils; for every 

 single bone that was discovered he searched in the neighbourhood for such 

 bones as appeared from their structure to belong to the first one found, if 

 the resultant skeleton nevertheless remained incomplete, he drew his con- 

 clusions from the structure of the available bones as to the habits of the 

 animal, and from them again as to the structure of the bones that were miss- 

 ing; from the bone-structure it was afterwards possible to determine the con- 

 struction of the soft parts. The accuracy of the method was still further 

 ensured by the extinct animal's skeleton being regularly compared in detail 



