In some of the caves, or abandoned mines, which I have visited, where the mushrooms are grown on a large scale, the practice in picking the mushrooms varies somewhat from that just described. In the first place, the mushrooms are allowed to stand on the bed longer, before they are picked. They are rarely, if ever, picked before they open. Mushrooms may be quite large, but if they have not opened, they are not picked. Very frequently, the plant may open, but, the operator says, it is not open enough. It will grow more yet. The object of the grower, in this case, is to allow the mushrooms to grow as long as it is possible, before picking, for the larger the mushroom, the more water it will take from the bed, and the more it weighs. This may seem an unprofessional thing for a grower to do, and yet it must be remembered that a large water content of the mushroom is necessary. The mushrooms grown in these mines are very firm and solid, qualities which are desired, not only by the consumer, but are desirable for shipment. These mushrooms are much thicker through the center of the cap than those usually grown in houses at a room temperature of 60° F. For this reason, the mushrooms in these caves spread out more, and the edges do not turn up so soon. Since the cap is so thick and firm at the center, it continues to grow and expand for some little time after having opened, without turning up on the edges, and without becoming black and unsightly underneath. These large and firm mushrooms are not only desirable for their shipping qualities, but also, if they are not too large, they are prized because they are of such a nice size for broiling. It is quite likely that one of the important conditions in producing mushrooms of this character is the low temperature of the mine. The temperature here, in July and August, rises not higher than 58° F., that is, the room temperature of the mines; while in the winter it falls not lower than 52°. The growth of mushrooms, under these conditions, may not be quite so rapid as in a house maintaining a room temperature of 60°. The operator may not be able to grow so many crops from the same area, during the same length of time; but the very fact that this low temperature condition retards the growth of the mushrooms is perhaps an important item in producing the firm and more marketable product, which can be allowed to grow longer before it is picked. It is possible, also, that another condition has something to do with the firmness and other desirable qualities of these mushrooms. It is, perhaps, to be found in the fact that natural spawn is largely used in planting the beds, so that the spawn is more vigorous than that which is ordinarily used in planting, which is several or many generations distant from the virgin condition.