The most numerous class of skins for light leathers is from the common sheep. These skins have particular value inasmuch as they include the wool as well as the pelt. This wool, which is actually the most valuable part of the sheep's skin, is the raw material of our woollen industries, and is one of the most important of animal proteids. We have, therefore, in this section to consider this dual value of sheepskins, the proteid of the epidermis (wool), and the proteid of the dermis (pelt); one the raw material of the woollen industry, the other the principal raw material of the light leather trade. The first problem is to separate the two proteids. With other skins and hides the ordinary liming processes were sufficient and appropriate, but in the case of sheepskins the method is unsuitable, because the exposure of the wool to the action of caustic lime and possibly other alkalies would seriously impair its quality and reduce its commercial value. Hence this separation of wool from pelt is usually quite a separate business, viz. that of the "fellmonger," whose occupation it is to collect the sheepskins from butchers and farmers, to separate the two important constituent proteids, and to hand the wool in one direction to the "wool stapler," who sorts it according to quality, and to hand the pelt in another direction to the light leather tanner, who tans and finishes the pelt to fit it for light upper work, fancy goods, etc. In the first instance, therefore, we have to consider the work of the fellmonger, the separation of wool and pelt. In this work the wool receives first consideration, and the raw material of the fellmonger is usually classified accordingly into "long wools," "short wools," and "mountain breeds." The skins vary very largely in quality of wool and in quality of pelt, being influenced very strongly by the conditions under which the sheep lived, and by the precise breed of animal from which the skin has been taken. As in the case of hides (Part I., Section I.), animals exposed to extremes of weather develop the best pelts, whereas those sheep which have been carefully bred and reared for the sake of their wool yield a thin and poor class of pelt. In Britain, and more especially in England, are reared the finest and most valuable sheep. This is evident from the prices paid for them by foreigners and colonial breeders when seeking new blood for their flocks and fresh stock for their lands. As much as 1000 guineas have been paid by an Argentine firm for a single Lincoln ram.