144 ON AFFINITY AND ANALOGY. 



be an affinity. In like manner the dragon-fly and the bat, 

 as animals, must possess a common relation of affinity when 

 compared with vegetables (the catch-fly plant for instance). 

 And even between animals and vegetables as compared with 

 inorganic matter, there must be a relation of affinity founded 

 upon the circumstance of their organized structure. 



To show then the existence of distinct relations of analogy 

 amongst these six animals of which we have thus traced the 

 affinities, it will be necessary to reverse the series as well as 

 the mode of comparison ; for if a relation of affinity of the 

 first degree be found to exist between the species of a genus 

 or sub- genus, the first degree of analogy will be found in the 

 objects most widely apart, that is in those belonging to dif- 

 ferent sub-kingdoms. Here then we find the bat and the 

 dragon-fly, belonging to different sub-kingdoms of the animal 

 kingdom (or next higher group), and we have already seen 

 that as compared together with reference to the objects of the 

 other next higher group (that is the vegetable kingdom), an 

 affinity existed between them ; but if, on the other hand we 

 regard the relations of the bat with any other animal belong- 

 ing to the same sub-kingdom as itself ( Vertebrata, the goat- 

 sucker for instance), we find the relation between the bat and 

 the dragon-fly to be so comparatively remote, that we term it 

 a relation of analogy. In like manner, if we compare the 

 goat-sucker with any other animal belonging to the same ver- 

 tebrated class as itself (birds, the swallow for instance), we 

 find the relation between either of these animals and any other 

 animals belonging to the other divisions {Reptilia, Pisces, 

 Mammalia, the bat for example) composing the next higher 

 group ( Vertebrata) to be one of analogy, as indeed Mr. Swain- 

 son has truly regarded it ; but by pursuing this train of rea- 

 soning, it will be equally evident that the relation between 

 the goat-sucker and the swallow, in comparison with that be- 

 tween the latter and the martin, is merely one of analogy and 

 not of affinity. 



In like manner we say that all the insects belonging to an 

 order (the Coleoptera for example), are related to each other 

 by affinity, as compared with the other orders of insects ; but 

 when we come to analyze the order Coleoptera, we find innu- 

 merable analogies existing amongst those very insects which 

 we have just previously admitted to possess a general affinity 

 with each other. 



It has long appeared to me to be most probable, that the 

 fact of two animals or groups of animals thus exhibiting rela- 

 tions both of affinity and analogy, was the chief cause which 

 induced many persons to regard both these relations as of 

 equivalent value, and as synonymous with resemblances. 



