(77.) _Influence of vegetation on form and disposition._--Vegetation influences, to a great extent, the form and disposition of the animal. Such changes may be brought about either by the plenty, or scarceness, of the herbage; or by the nature of the country on which that herbage is produced. Animals found on hilly countries are always widely different from those of the plains. Their bodies are light, their legs long, and their habits of that unquiet kind which renders them hostile to any thing like restraint. It is for these reasons, that when once a flock attaches itself to a range of hills, and becomes suited to the means of subsistence, it may preserve itself for ages apart from neighbouring varieties, and present, after a long series of years, those qualities in their native purity for which it was noted by the earliest observers. The sheep of a level country are distinguished, on the contrary, by heavy bodies, short legs, and easy tempers. They are, in fact, constructed on Dutch proportions, and are imbued, as a natural consequence, with those imperturbable and steady-going habits so characteristic of the bulbous bottomed Hollander. Subdued as they are by the nature of their locality, they readily submit to man, who tutors them at will, and works on them those profitable changes from which have originated our improved varieties. As connected with the unquiet dispositions of hill sheep, I may mention the prevalence of a notion, that domesticated sheep cannot by any possibility become wild. From all that I have seen, and read, I am led to believe, though the sheep, according to Greek, Roman, and Oriental philosophers, was the first animal domesticated, that when at liberty it will soon return to its primitive and instinctive habits. Bonnycastle, in his work on Spanish America, remarks, that sheep are found in a state of nature, in the northern parts of New Spain, "having multiplied to an extraordinary degree in the wide-spread plains, and savannahs." In ascending our Scottish mountains, every one must observe the state bordering upon wildness, in which the sheep appear, roving in detached but well-led parties; bounding away to the most inaccessible places on the approach of danger, and peering from the eminences in all the pride of scornful independence. Professor Blumenbach at one time doubted the possibility of domestic sheep ever becoming wild; but his opinion was changed on perusing the work of Vincentius, where there occurs a remarkable passage, in which Nearchus, when speaking of the desert island of Cataia, on the coast of Caramania, says, that the inhabitants of the neighbouring islands yearly carried thither sheep, as offerings to Venus and Mercury, and that, in course of time, they became wild in the deserts.[13] Constant attendance is, therefore, called for on the part of man, to ensure that untroubled reliance on his care so conducive to the welfare of the flock, for even on a temporary cessation of his