Brick spawn from other sources presents a very different texture and contains probably a much larger percentage of horse manure, or, at least, a much smaller percentage of soil. The appearance of the brick is not that of soil with a slight admixture of vegetable materials, but has much the appearance of a dried and compressed mixture of horse dung and cow dung, with an abundance of the "fiber" or mycelium, "the greyish moldy, or thready matter," which constitutes the vital part of the spawn. In the selection of spawn this is an important item, that is, the presence of an abundance of "fiber" or mycelium. It can be seen on the surface, usually showing an abundance of these whitish threads or sheets, or a distinct moldy appearance is presented. On breaking the brick the great abundance of the "fiber" or whitish mycelium is seen all through it. This indicates that the brick possesses a high percentage of the "fiber," an important part of the spawn. One not accustomed to the quality of spawn can therefore judge to a certain extent by the appearance of the bricks as to the quality, at least they can judge as to the presence of an abundance or a scanty quantity of the "fiber." Since the spawn remains in good condition for several years, there is usually no danger in the use of spawn which may be one or two years old. But it does deteriorate to some extent with age, and young spawn is therefore to be preferred to old spawn, provided the other desirable qualities are equal. Those who attempt to cultivate mushrooms, and depend on commercial or manufactured spawn, should see to it that the spawn purchased possesses these desirable qualities of texture, and the presence of an abundance of the mycelium. That which appears devoid of an abundance of mycelium should be rejected, and good spawn should be called for. There is no more reason why a grower should accept a worthless spawn from his seedsman than that he should accept "addled" eggs from his grocer. In this business, that is, the manufacture and sale of spawn, poor material is apt to be thrown on the market just as in the case of seeds, poor material may find its way upon the market. Sometimes this occurs through unscrupulous dealers, at other times through their ignorance, or through their failure to know the quality of the product they are handling.