How do you suppose deserts that get so little rain themselves could _help make it rain_ in other places? For example, the desert of Thibet is the chief cause of the monsoon rains that do so much for India. That part of your geography that explains the circulation of the air will help you figure this out; particularly with a map under your eye that shows the relative location of the desert and the Indian Ocean, over which the monsoon winds blow. [Illustration: AN EXAMPLE OF MAN'S DEBT TO THE EARTHWORM Much of the earth's Maytime bloom and beauty is due to the labor of our humble little brother of the dust, the earthworm; a striking fact which was never recognized until the great Charles Darwin looked into the matter and wrote a book about him. This picture by Millet is called "Springtime" and hangs in the Louvre, in Paris.] CHAPTER V (MAY) It may be doubted whether there are many other animals which have played so important a part in the history of the world as these lowly organized creatures. --_Darwin: "The Formation of Vegetable Mould."_ WHAT THE EARTH OWES TO THE EARTHWORM Suppose father had a hired hand who would plough his fields, fertilize them at his own expense, build his own house, board himself, and for all this ask only the privilege of living on the place, studying Botany, Geology, and Geometry, and enjoying the scenery. "Where can I get a man like that?" I imagine father saying. "You've got him now," you might reply. "He's already working for you--thousands of him, and has been working for you--millions of him--for thousands and millions of years." We have all known him well from boyhood by several names--angleworm, fishworm, earthworm. He also, as you will find in the dictionary, has a nice long Latin title. And it is particularly fitting that his name should be so associated with antiquity, since he belongs to one of the oldest families in the world; a family far older than the Roman Empire itself, which his people long ago helped grind back into the dust from which it came. And, speaking of Romans, every few years Mr. Earthworm does what Julius Cæsar did, captures the whole of England--all the best parts of it--and then, unlike Cæsar, gives it back to the English, made over again, better than it was before, as you will see. I. THE CITIES OF WORMS If you happen to be a high school boy you, of course, know about a certain city of Worms and what great things took place there once upon a time, but there are many cities of worms on any good farm, and each has more inhabitants than the famous city of Worms of history--something like 25,000 to the acre; and, in garden soil, 50,000! [Illustration: ANOTHER "CATHEDRAL OF WORMS"