And before the others could ask explanation of this scene a bicycle came flashing up to the same gate, and the tall rider dismounted and strode quickly toward the party. Young Fred's eyes glistened at sight of him. "Orders, Sergeant?" he eagerly inquired. "Yes. Notify your squad to make arrangements with their employers, and be ready to report at the armory at a moment's notice." The two brothers stood facing each other a little later, then silently clasped hands. One at the beck of a secret protective organization, the other at the call of duty to State and nation, parted at their father's gate to go their separate ways. [TO BE CONTINUED.] A BOY'S AQUARIUM. Boys who live in the city do not, perhaps, get quite the freedom of action and fun generally that a country boy can, but they do manage to have a pretty good time, even if they have to work a little harder for it. It is hard to keep pets in the city. Dogs need a lot of exercising, birds are apt to be a nuisance to the neighbors, if not to the boy's family, and yet pets are a necessity to every well-brought-up boy's happiness. An aquarium is always dear to every boy's heart. And aquariums are not impossible in a city house. Fortunately they can be just as well taken care of in the city as in the country. A medium-sized aquarium which will hold quite a lot of stuff can be bought for $1.50 or $1.75. This must be filled with gravel or sand to the depth of four inches. In the sand must be, securely fastened, some water-grasses, which are for sale at any of the stores where fish are to be bought. The boys who succeed best with their aquariums are those who study the matter pretty thoroughly before they begin, and read up the scientific books of natural history. The simpler works of this sort contain any amount of practical information which any boy can apply to his own use. A porous stone seems to be necessary in the middle of the aquarium. As for the placing of the water plants, they must be left to the boy's own taste and judgment. Indeed, the arrangement of the whole aquarium must be left to the boy who owns it. In this place I must stop and say that it is foolish for any boy to consult many of his playmates as to how the thing should be arranged, for when he has asked and received much advice, he will find that most of it is directly opposed to what he already knew, and besides is so varied as to be nearly useless. A glass tube for removing the manure from the sand must be kept beside the aquarium, if the scavengers, such as pollywogs and snails, fail to do their duty in cleaning up.