I suppose that every one, or nearly every one, knows that these swarming little black tadpoles are the young of frogs and toads. As the season goes on they grow to as much as an inch and a quarter (sometimes an inch and three-quarters) in length, and develop a number of golden metallic-looking spots in the skin, which give them a brownish hue. Both the fore and the hind limbs have now developed, but are hidden beneath the skin, and all this time the tadpole is breathing, like a fish, by means of gills, concealed from view by a fold of skin. Very early it acquires a pair of lungs, and by the time the legs break through the skin (the hind legs do so first) the lungs are inflated, and help in respiration. Now the head becomes modelled like that of a young frog, the tail ceases to grow, its flat transparent border is absorbed and eaten by “phagocytes,” and the legs become strong and large. Soon the gills atrophy, and the young creature crawls out of the water and spends much of its time in the damp grass and herbage near its native pond, rapidly assuming the shape of a frog. An interesting fact is that all the time that it is a tadpole the little animal eats vegetable food or soft animal food (even other tadpoles), has horny lips, and a very long intestine, coiled like a watch-spring. But as soon as it leaves the water it becomes purely carnivorous, feeding on small insects and worms, and its intestine straightens out and becomes, relatively to the increased size of the body, quite short.