CHAPTER XIII. 



THE cat's place IN NATURE. 



§ 1. Nothing can be understood by itself. All oui' knoAvledge 

 consists of apprehensions wbicli have been acquired by comparing 

 and contrasting one thing with another ; and the more we know of 

 any object, the greater is the number of relations we are able to affirm 

 to exist between it and other objects. To fully understand any 

 living creature, then, we should understand, as far as we can, the 

 various relations in which it stands to all other living creatures : 

 More than this, we should also understand its relations with that 

 part of the creation which is devoid of life — in short, we should 

 understand " its jJ^fice in natia'e." 



But the reader may deem such an inquiry superfluous as regards 

 the animal which we have elected to study ; for any one who is 

 asked, " What is a cat? " will at once reply "A beast of a certain 

 kind which preys on other animals ; " and if again asked " What is 

 meant by a beast?" will probably say, "a living four-footed 

 animal." If, however, the inquiry be pressed further, and precise 

 meanings of " living creature," " animal," " beast," and " beast of 

 prey," be demanded, the unsatisfactoriness of mere vague, popular 

 conceptions will be plainly shown. We must then endeavour to 

 obtain a full, clear, and precise knowledge of what is, or should be, 

 meant by the above terms, so that we may be able to answer the 

 question, " What is a cat ? " with accuracy, and with a sufficient 

 comprehension of the expressions employed in so answering. AVe 

 must know "the why and the wherefore" of the terms of our 

 answer. 



§ 2. Now, in the first place, wc have seen that the body of the 

 cat is bounded on all sides by curved lines and surfaces. Secondly, 

 we have recognised that its body consists of different organs and 

 tissues, and that wherever wc may cut through it, wc come upon 

 parts which differ one from another — its body, therefore, is anything 

 but homogeneous. A third fact about the cat's body concerns its 

 chemical composition. Wc have seen that a great uniformity exists 

 in this respect, and that all the main portions of it — its flesh, its 

 nerves, its blood, &c. — are reducible to oxygen, hydrogen, carbon, 

 and nitrogen, of which (with the addition of a minute quantity of 



