36 CLASSIFICATION 



The first principles are but few ; but it is the various forms of those 

 principles that produce such variety of animals. Out of these principles 

 Nature has first produced three classes of animals to answer the three 

 elements; therefore there is a similarity in each class, more than between 

 any two of these classes. This is the first division : these are subdivided 

 into a great many fitted for other variations of nature. As a general de- 

 scription would answer all animals, viz. what an animal was, and as the 

 animals are divided into three classes, so must the description ; then 

 each class is again subdivided, which subdivides our description 1 . 



In treating of any one animal, tracing it through the circle of life, 

 we move as it were in a circle : for, at whatever stage of its progress 

 we begin, we come to the same stage again before we complete the 

 whole circle. If we begin at its rise and go through its whole progress, 

 we are led naturally to the same point again, viz. to the production of 

 another animal similar to the present 2 . 



Of perfect and imperfect Animals. 



Nature has, in the most perfect animals, formed parts very distinct 

 from one another, for all the different functions or operations of the 

 body ; whereas, in the more imperfect, she has huddled parts together, 

 and made some serve two purposes, or has joined two into one. For 

 instance the ureters of the Bird enter the anus ; — the penis, vasa defe- 

 rentia or oviducts, enter the anus 3 . Still more imperfect animals have 

 heart and stomach in one. 



The more imperfect animals are, the greater is the tendency or dis- 

 position they have for parts which have been removed to be restored. 



I gelded a young cock ; and, after having let him live eight months, 

 I found that a small part which had been left was become much larger. 

 [By the way, talking of cocks] cocks' combs are parts that do not in- 

 flame though ever so much wounded ; this we see in cutting them when 

 they have fought, &c. 



Progression and Declension of perfection in Animals. 



What we call ' perfection' in animals does not increase in regular 

 progression in every part, but as animals are complicated ; and each 



1 [This characteristically Hunterian MS. may healthily exercise the ingenuity of 

 some readers to decipher its full meaning.] 



2 [" The organs of animals form the links of a chain, and their functions form a 

 continued circle of renovation and decay." — Cuvier.] 



3 [Here Hunter enunciates the principle of ' differentiation of structure ' as cha- 

 racteristic of grade. He might have cited many better examples, and such will 

 readily suggest themselves to the naturalist.] 



