VARIETIES INDUCED BY TEMPERATURE. 



71 



of his able biographer, Mr Scot of Selkirkshire, " like 

 the land of Goshen, good for cattle which it is to this 

 day." 



(66.J Varieties among Animals. — All organized mat- 

 ter 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 indivi- 

 duals 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 ditference, endless though they are, may be 

 referred to two leading causes — climate and descent; 

 the former embracing deviations induced by tempera- 

 ture and resources of subsistence ; the latter including 

 changes occasioned by management, modes of breeding, 

 and influence of sex. 



C67.) Varieties induced by Temperature. — The influ- 

 ence 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 be- 

 comes 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 

 f»ry different do we not find the colours of intertropical 



