The reason you see so many worms after a rain is that earthworms like moisture, and the rain seems to make them feel particularly good and breed a spirit of adventure. So out of their holes and away they go! A rain is their shower-bath; and you know how a shower-bath makes you feel. The mornings when the earthworms are apt to be thickest are those following a comparatively light rain in early Spring when the worms have recently awakened from their long Winter nap. With the beginning of the rainy season in the Fall, the worms also do a good deal of travelling into foreign lands, but in both Spring and Fall you will usually find more worms after a light shower than after a long, heavy downpour. If the worms were drowned out it would be the other way around, don't you see? To be sure, you will often find dead worms in shallow pools by the roadside; particularly after Autumn rains. These are sick worms and the chill was too much for them. But it's remarkable how low a temperature a good husky angleworm can stand. A professor in the University of Chicago, near which I live, tells me he has often found the ground in the neighboring park covered with worms after November rains when his hands, and those of the students who were helping him gather them for study, were numb with the cold. And how much work do you suppose these farmers do in grinding up and fertilizing the soil? In many parts of England the whole of the best land--the vegetable mould--passes through their bodies every few years, and they are doing similar work all over the world. They not only fertilize the earth by mixing it with the leaves they eat and those that decay in their burrows, but their castings help to bury fallen leaves and twigs and dead insects, and they also bring up lower soil to the surface, thus increasing its fertility. And by loosening the soil they let in more air. Remember that roots, like people, must have air. III. THE MILL OF THE EARTHWORM For the grinding up of the earth and the leaves, the earthworm has, as I have already said, a little mill that he always carries with him. Do you know what a gold mill is? Well, a gold mill is a mill that grinds up rock and so grinds out the gold. The earthworm's mill, in a manner of speaking, also grinds out gold, for it grinds the little particles of stone in the soil, and this soil grows fields of golden grain. The earthworm's mill is his gizzard. This gizzard is made and works very much like the gizzard of the chicken. And like the chicken the earthworm swallows little stones to help his digestion. So these stones, too, are ground into soil.