254 ZOOLOGY. 



405. The capacity and length of the intestines are much 

 less in the carnivora than in the herhivora, being in many of 

 the former only three or four times the length of the body ; 

 whilst in the sheep, for example, it is nearly eight times that 

 length. Generally it terminates by a distinct opening ; in 

 the ornithorhynchus, however, the anus opens into a cloaca, 

 or cavity, in which terminate also the urinary organs, resem- 

 bling birds in this respect. The salivary glands, the liver, 

 pancreas, peritoneum, and its appendages, resemble the same 

 organs in man. 



406. The more essential differences exist in the apparatus 

 of respiration and circulation; the heart has always two auricles 

 and two ventricles ( 92, Figs. 39, 40) ; the lunajs are always 

 composed of cellules, which do not allow the air to escape into 

 the other organs of the body, as in birds. The blood is rich 

 in organized matters, and the form of the globules circular 

 ( 81, Fig. 36). 



407. We have already shown that the mammals differ 

 widely from each other in respect of intelligence ( 337) ; 

 and the various instincts bestowed on them by nature to 

 supply the deficiency of a higher intelligence have been 

 already alluded to. It is the class which most interests man, 

 including within it, as it does, so many of our domestic ani- 

 mals ; the horse, ox, sheep, &c. So complete, indeed, have 

 been the effects of domesticity over some of these races of 

 animals, that the primitive race seems altogether to have 

 disappeared. The moral as well as the physical characters of 

 the domesticated races are thus affected and altered. The 

 dog, for example, so varied by domestication, may yet have 

 sprung from a single race, neither a wolf nor a jackal, but a 

 dog analogous to the common shepherd's dog, or wolf-dog, as 

 it is sometimes called. 



The power by which this complete sutfjugation of a race of 

 animals is effected seems to be the inspiring them with con- 

 fidence by kind acts and uniformly good treatment. We 

 must show them that the supply of food depends on us ; and 

 if to that we add food of a choice character, artificial wants 

 are thus created, which the animal feels man alone can 

 gratify. Hence his attachment to him ;* finall} r , some are 

 extremely fond of being noticed and made much of. 



Confidence and dependence on man being once established, 



* It is chiefly by means of sugar and other delicacies that horses and deer 

 are fanght those extraordinary tricks exhibited in the circus. 



