In pastures, however, where the dry stalks of the burdock, or the hound's-tongue, or tory-weed have remained standing over the winter, the burs are caught in the now long wool, and, if they are numerous, the wool is rendered entirely unmarketable and almost valueless. Even the dry prickles of the common and Canada thistles, where they are very numerous, get into the neck-wool of sheep, as they thrust their heads under and among them to crop the first scarce feed of the northern spring; and, independently of injuring the wool, they make it difficult to wash and otherwise handle the sheep. Indeed, it is a matter of the soundest policy to keep sheep on the cleanest pastures, those free from these and similar plants; and in a region where they are pastured the year round, they should be kept from contact with them for some months prior to shearing. Many prepare _artificial pastures_ for their flocks, which may be done with a number of plants. Winter rye, or wheat sown early in the season, may be fed off in the fall, without injury to the crop; and, in the following spring, the rye may be pastured till the stalks shoot up and begin to form a head. This affords an early and nutritious food. Corn may be sown broadcast, or thickly in drills, and either fed off in the fields or cut and carried to the sheep in their folds. White mustard is also a valuable crop for this purpose. To give sheep sufficient variety, it is better _to divide their range_ into several smaller ones, and change them as often, at least, as once a week. They seek a favorite resting-place, on a dry, elevated part of the field, which soon becomes soiled. By removing them from this for a few days, rain will cleanse or the sun dry it, so as to make it again suitable for them. More sheep may be kept, and in better condition, where this practice is adopted, than where they are confined to the same pasture. SHADE. No one who has observed with what eagerness sheep seek shade in hot weather, and how they pant and apparently suffer when a hot sun is pouring down upon their nearly naked bodies, will doubt that, both as a matter of humanity and utility, they should be provided, during the hot summer-months, with a better shelter than that afforded by a common rail-fence. Forest trees are the most natural and the best shades, and it is as contrary to utility as it is to good taste to strip them entirely from the sheep-walks. A strip of stone-wall or close board fence on the south and west sides of the pasture, forms a tolerable substitute for trees. But in the absence of all these and of buildings of any kind, a shade can be cheaply constructed of poles and brush, in the same manner as the sheds of the same materials for winter shelter, which will be hereafter described.