The silk-worm moths are excellent illustrations of what is called complete metamorphosis in insects. An insect like the grasshopper, when it hatches from the egg, is very much like the adult insect in its general form and appearance; the most evident difference being the lack of wings. An insect which shows such slight changes in its growth to maturity is said to have an incomplete metamorphosis. It is incomplete in the sense that the change is not of a very radical nature. But in the case of the silk worm moths, and moths and butterflies in general, the larva which hatches from the eggs has not even the most superficial resemblance to the adult insect, the fully-developed moth. This necessitates a complete change or metamorphosis in the form and structure of the insect before it can become mature. This great change is accomplished during the quiet pupal stage in the cocoon. Because the pupa is apparently passive when viewed from the exterior, one must not conclude that it is so internally; far from it; the digestive organs of the larva must be completely made over from those of a chewing leaf eater to those of a moth which can only take liquid food. Charles Christopher Adams. CASTLES IN THE AIR. In a little bend of the San Joaquin River, where the current, attempting to straighten its course, has left a bank a few feet wide, there is a small grove of tall cottonwood trees, perhaps a dozen in number, whose branches lean far over the stream and whose tops reach almost to the level of the bluff or rather the floor of the valley 250 feet above, for this swift river has, in the course of ages, cut thus deep a channel for itself. The place is not easy of access, for the shore narrows above and below the bend to a few inches where one with difficulty keeps from crumbling away the sand with his feet and falling into the water, and the cliff is so nearly perpendicular that in many places it is inaccessible to a climber, being of soft sand whose different stratas are clearly defined where they have been sliced off by the cutting stream. The valley above is a vast grainfield out almost to the edge of the bluff, and along the edge and face of the bluff, wherever root can cling or tendril hold, grow beautiful wild flowers in the early spring days--their last refuge between the cultivation and the deep sea, or rather, river.