About seventy years ago, improvements also commenced in Scotland. Till then, in many parishes, no farmer could keep sheep through the winter, and no place was reckoned so fatal to these animals as the undrained, and unsheltered parish of Eskdale-Muir, in Dumfriesshire. At last one William Bryden rented the farm of Aberlosk, and soon, by the _original_ plan of draining, and building stone enclosures, made it, to use the words of his able biographer, Mr Scot of Selkirkshire, "like the land of Goshen, good for cattle which it is to this day." (66.) _Varieties among Animals._--All organized matter is subject to variety. It may be doubted whether, since the creation of the world, there have ever occurred, either at the same, or at separate periods, two individuals in every respect perfectly alike. A plant, or an animal, may resemble the rest of its species in chemical constitution, and in the number and situation of its organs, but is sure to differ from all in size, general configuration, and disposition of its parts: These shades of difference, endless though they are, may be referred to two leading causes--climate and descent; the former embracing deviations induced by temperature and resources of subsistence; the latter including changes occasioned by management, modes of breeding, and influence of sex. (67.) _Varieties induced by Temperature._--The influence of temperature extends chiefly to the _colour_ and _development_ of animals. In cold regions the skin of the human race is fair, and the person squat and stunted, but as we approach the equator, the hue becomes deeper and deeper, till it is jetty black, while at the same time, the stature attains nearer and nearer to the tallest proportions to which mankind seem naturally entitled. The animals of the arctic regions are, for the greater part of the year, covered with a clothing of the purest white, which is, however, in many of them, abandoned for one of deeper tints as the solar heat begins to gain the ascendant. But how very different do we not find the colours of intertropical animals. There vivid tints, and an almost metallic lustre, pervade animated beings, from the coral in its submarine abode, to the gallinaceous birds, the coxcombs of the forest. In this, as in every other department of nature, the most beautiful harmony, or, in other words, a union of what is pleasing to the eye, and suited for the comfort of the creature, every where prevails. The colour of an animal envelope is never at variance with the tints of surrounding objects. A painter, for example, would not place a flower or animal of brilliant hue amidst the monotonous aspect of an arctic landscape; neither would he picture the faintly-tinted beings of a polar latitude, as surrounded by the warm and flashy colouring characteristic of an oriental climate. As temperature, then, determines in a marked degree the colour and dimensions of every animal, such variations render the division of living beings into races