54 KTIMNNK GEOF1 ROY SAINT-HILAIRE 



Vertebrate there are found the same " organic materials," or 

 units of construction. This conception, which Geoffrey calls 

 the Tlicoric dcs analogues (p. xxxii.), is clearly one part of the 

 old idea of the unity of type ; it teaches the unity of 

 composition of organic beings, while the Principe dcs 

 connc.vions adds the unity of plan. 



Both conceptions are logically implicit in the vague 

 notion of unity of type ; Geoffrey disengaged them, and 

 pushed each to its logical extreme. 



Most of the ordinary homologies of structure in air- 

 breathing Vertebrates have already been seized, he continues, 

 for they are more or less obvious, and many intermediate 

 states exist (p. xxxiv.). But ordinary methods of comparison 

 fail when the attempt is made to homologise the structure 

 of fishes with that of air-breathing Vertebrates, for the 

 homologies are anything but obvious and no intermediate 

 organs are found. 



Most air-breathing Vertebrates have a larynx, a trachea, 

 and bronchi, which are absent in fish ; and fish have many 

 parts which seem to be absent in higher Vertebrates. But 

 apply the " Theory of Analogues " ; it teaches that there can 

 be no organ peculiar to fish and not found in other 

 Vertebrates; apply the "Principle of Connections," it will 

 show which organs are homologous in the two types 

 (p. xxxv.). 



Comparative anatomists, with few exceptions, had hitherto 

 taken man as the type, and referred all structure to his ; 

 Geoffrey's principles led him to give preference to no one 

 animal in particular, but to seize upon each part in the 

 species in which it reaches the maximum of its development 

 (p. xxxvi.). He is thus led to refer all structures to a 

 generalised abstract type. In this abstract type each organ 

 exists at the maximum of its development, each organ shows 

 all its potentialities realised. In a way, therefore, this type, 

 this abstraction, gives the scheme of the possible transforma- 

 tions of each organ. 



It is true Geoffroy does not refer to this " Archetype" in 

 so many words, but it must always have been vaguely 

 present in his mind. He has this idea in his head when he 

 says in one of his later works, " There is, philosophically 



