(3/91. Erman 'Travels in Siberia' English translation volume 1 page 228. For Pallas on the fat-tailed sheep I quote from Anderson's account of the 'Sheep of Russia' 1794 page 34. With respect to the Crimean sheep see Pallas 'Travels' English translation volume 2 page 454. For the Karakool sheep see Burnes 'Travels in Bokhara' volume 3 page 151.) In all such cases, however, it may be that a change of any kind in the conditions of life causes variability and consequent loss of character, and not that certain conditions are necessary for the development of certain characters.
Great heat, however, seems to act directly on the fleece: several accounts have been published of the change which sheep imported from Europe undergo in the West Indies. Dr. Nicholson of Antigua informs me that, after the third generation, the wool disappears from the whole body, except over the loins; and the animal then appears like a goat with a dirty door-mat on its back. A similar change is said to take place on the west coast of Africa. (3/92. See Report of the Directors of the Sierra Leone Company as quoted in White 'Gradation of Man' page 95. With respect to the change which sheep undergo in the West Indies see also Dr. Davy in 'Edin. New. Phil. Journal' January 1852. For the statement made by Roulin see 'Mem. de l'Institut present. par divers Savans.' tome 6 1835 page 347.) On the other hand, many wool-bearing sheep live on the hot plains of India. Roulin asserts that in the lower and heated valleys of the Cordillera, if the lambs are sheared as soon as the wool has grown to a certain thickness, all goes on afterwards as usual; but if not sheared, the wool detaches itself in flakes, and short shining hair like that on a goat is produced ever afterwards. This curious result seems merely to be an exaggerated tendency natural to the Merino breed, for as a great authority, namely, Lord Somerville, remarks, "the wool of our Merino sheep after shear-time is hard and coarse to such a degree as to render it almost impossible to suppose that the same animal could bear wool so opposite in quality, compared to that which has been clipped from it: as the cold weather advances, the fleeces recover their soft quality." As in sheep of all breeds the fleece naturally consists of longer and coarser hair covering shorter and softer wool, the change which it often undergoes in hot climates is probably merely a case of unequal development; for even with those sheep which like goats are covered with hair, a small quantity of underlying wool may always be found. (3/93. 'Youatt on Sheep' page 69 where Lord Somerville is quoted. See page 117 on the presence of wool under the hair. With respect to the fleeces of Australian sheep page 185. On selection counteracting any tendency to change see pages 70, 117, 120, 168.) In the wild mountain-sheep (0vis montana) of North America there is an analogous annual change of coat; "the wool begins to drop out in early spring, leaving in its place a coat of hair resembling that of the elk, a change of pelage quite different in character from the ordinary thickening of the coat or hair, common to all furred animals in winter,--for instance, in the horse, the cow, etc., which shed their winter coat in the spring." (3/94. Audubon and Bachman 'The Quadrupeds of North America' 1846 volume 5 page 365.)
A slight difference in climate or pasture sometimes slightly affects the fleece, as has been observed even in different districts in England, and is well shown by the great softness of the wool brought from Southern Australia. But it should be observed, as Youatt repeatedly insists, that the tendency to change may generally be counteracted by careful selection. M. Lasterye, after discussing this subject, sums up as follows: "The preservation of the Merino race in its utmost purity at the Cape of Good Hope, in the marshes of Holland, and under the rigorous climate of Sweden, furnishes an additional support of this my unalterable principle, that fine-woolled sheep may be kept wherever industrious men and intelligent breeders exist."
That methodical selection has effected great changes in several breeds of sheep no one who knows anything on the subject, entertains a doubt.