1843-44 HUNTERIAN LECTURES 215 



another organ in the same body, by considering 

 them in relation to the general nature and powers 

 of the entire animal, together with its relations to 

 other animals, and to the sphere of its existence, 

 that we are chiefly enabled to elucidate the uses 

 of the several super-additions which are met with 

 in following out the series of complexities of a 

 single organ. 



' But comparative anatomy fulfils only a part 

 of its services to physiology if studied exclusively 

 in relation to the varieties of a given organ in 

 different animals. The combinations of all the 

 constituent organs in one animal must likewise 

 be studied ; and these combinations, with the 

 principles governing them, or the correlations of 

 organs, must be traced and compared in all their 

 varieties throughout the animal kingdom. It is 

 in this point of view that I now propose to treat 

 upon the leading facts of comparative anatomy, 

 to discuss and demonstrate the organs as they 

 are combined in the individual animal, and, com- 

 mencing with the lowest organised species, in 

 which the combination is of the simplest kind, to 

 trace it to its highest state of complexity and 

 perfection through the typical species of the suc- 

 cessively ascending primary groups and classes 

 of the animal kingdom. In short, as my pre- 

 vious courses of Hunterian Lectures, agreeably 

 with the arrangement of the Hunterian Collection, 

 have treated of comparative anatomy according 



