198 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



of trees. All the herbivora are possessed of instincts which enable them 

 to select the vegetable foods which are most suitable for them, and will 

 reject others. Thus, it has been found, as mentioned by Colin, who has 

 made a close study of this subject, and to whom the author is largely 

 indebted, that a horse will eat 262 different kinds of plants, and has been 

 seen to reject 212 ; the ox will eat 275 and refuse 218 ; the sheep will eat 

 387 and refuse 141 ; the hare will eat 449 and refuse 125 ; and the pig, 

 which is omnivorous, and yet which can be sustained by vegetable food, 

 has been found to devour 172 different kinds of vegetable matter and 

 reject 171. Different circumstances, such as changing seasons or migra- 

 tion from different localities, may compel them to feed on plants which 

 are otherwise ordinarily refused. Their instinct leads them, further, to 

 avoid venomous plants when mixed with other plants, or unless greatly 

 pressed by hunger. Different plants are poisonous articles of food to 

 some animals, while other plants are poisonous to others. Here it is only 

 necessary to mention that the ox and rabbit may eat belladonna with 

 impunity, the goat hemlock, the horse aconite, while goats and sheep 

 avoid most of the solanacese. 



The omnivora are permitted, by their organization and instinct, to 

 devour both kinds of food, and, as a consequence, their habits are not so 

 sharply characterized as either of the two above-mentioned groups. They 

 ma} r live either on exclusively animal or exclusively vegetable diet, accord- 

 ing to circumstances. The pig, the rat, gallinaceous fowls, flat-footed 

 birds, the raven and crow are all omnivorous. Many animals placed 

 among this species from the characteristics of their organization appar- 

 ently belong to the carnivora, such as the bear, the fox, and dog ; and 

 these animals are also omnivorous, although to a less-marked degree than 

 the preceding examples. The hog and wild boar live on roots, insects, 

 and reptiles. Rats and mice, strictly speaking, are. omnivorous, since 

 they devour ever} T thing that comes within their reach. 



The duck, which ordinarily seeks aquatic regions, where it can feed 

 on tender vegetable shoots and small aquatic animals and insects, may 

 also be brought to live on a purely vegetable or even a purely animal diet. 

 Also, the fox will live on fruits when animal food is not accessible. Bears, 

 while distinctly carnivorous in their type of organization, are also omniv- 

 orous animals, and will often live exclusively on roots, honey, etc. So 

 the sea-otter may be brought to live 011 vegetable matter when fish cannot 

 be obtained. The dog, again, is strictly carnivorous in its organization, 

 and yet can live on purely vegetable matter, and in its state of domesti- 

 cation this diet seems to suit him best. A great number of animals 

 belonging to these species have distinct tastes for certain mineral sub- 

 stances, especially common salt; and this is, above all, marked in the 

 herbivora, which perish when deprived of salt, and, as is well known, will 



