200 CLOSE OF THE PRE-EVOLUTIONARY PERIOD 



considered adequate to explain the rich variety of animal 

 forms. We cannot do better than quote his own summary 

 of his doctrine: "To sum up, then, the great differences 

 introduced by Nature into the constitution of animals seem to 

 depend essentially upon the existence of a certain number of 

 general plans or distinct types, upon the perfecting in 

 various degrees either of the whole or of parts of each 

 of these structural plans, upon the adaptation of each type to 

 varied conditions of existence, and upon the secondary 

 imitation of foreign types by certain derivatives of each par- 

 ticular type " (p. 480). 



We have laid stress on the fact that Milne-Edwards 

 put function before form, for this is the mark of the true 

 Cuvierian. With it goes the belief that Nature forms new 

 parts to meet new requirements, that she is not limited, as 

 Geoffroy thought, to a definite number of "materials of 

 organisation," but can produce others at need. Cuvier held, 

 for example, that many of the muscles and even the bones 

 of fish were peculiar to them, and without homologues in 

 the other Vertebrates, having been created by Nature for 

 special ends. 1 So, too, Johannes Miiller, who in many ways 

 and not least in his sane vitalism was a follower of the 

 Cuvierian tradition, recognised that many of the complicated 

 cartilages in the skull of Cyclostomes were specially formed 

 for the important function of sucking, and had no equivalent 

 in other fish. 2 



So, too, the embryologists after Cuvier often came across 

 instances of the special formation of parts to meet temporary 

 needs. Thus Reichert interpreted the " palatine " and 

 " pterygoid," which are formed in the mouth of the newt 

 larva by a fusion of conical teeth, as special adaptations to 

 enable the little larva to lead a carnivorous life. 3 



Not many years after the publication of Milne-Edwards' 

 Introduction a la soologie gtntrale (1851) there appeared a 

 book by II. G. Bronn in which was offered a very similar 

 analysis of organic diversity. The curious thing was that 



1 Cuvier et Valenciennes, Hist. nat. Jcs Foissons, i., p. 550, 1828. 

 -' Myxinoidcn, Th. I. Abh. k. Akad. Wiss. Berlin for 1834, pp. 

 loo, no, 179, etc. 



1 Vcrgl. Enlw. Kopf. nackt. Amphibicn, p. 101, 1838. 



