The author wishes to make special acknowledgment to the following publishers for their courtesy in supplying illustrations:

The Macmillan Company for the pictures from Tarr and Martin's "College Physiography" on page 239; Darwin's "Formation of Vegetable Mould" on page 77.

D. Appleton and Company for the pictures from Gilbert and Brigham's "Introduction to Physical Geography" on page 94; "Picturesque America" on page 243.

J. B. Lippincott Company for the pictures from Beard's "American Boy's Book of Bugs, Butterflies, and Beetles" on page 229; McCook's "Natural History of the Agricultural Ant of Texas" on pages 206 and 213.

McClure's Magazine for the pictures on pages 149 and 157.

Scientific American Publishing Company for the picture from "Scientific American Boy at School" on page 227.

Harper and Brothers for the pictures from McCook's "Nature's Craftsmen" on pages 98, 105, 109, 207, and 208.

Strand Magazine for the pictures on pages 165, 182, and 204.

Charles Scribner's Sons for the pictures from Yard's "Top of the Continent" on page 5; "Country Life Reader" on pages 9, 64, 85, 114, 186, and 241; Osborn's "Men of the Old Stone Age" on page 33. Hornaday's "American Natural History" on pages 116, 117, 119, 123, 130, 144, and 225; Seton's "Life Histories of Northern Animals" on pages 123, 129, 147, and 151.

Henry Holt and Company for the pictures from Beebe's "The Bird, Its Form and Function" on page 167; Salisbury's "Physiography" on pages 55, 71, and 167.

Carnegie Institution of Washington for the pictures on pages 8 and 69.

University of Nebraska for the picture on page 37.

Columbia University Press for the picture from Wheeler's "Ants and Their Structure" on page 95.

Houghton Mifflin Company for the pictures from Sharp's "Year Out of Doors" on page 11; "Riverside Natural History" on page 117; Mill's "In the Beaver World" on pages 152 and 153.

Ginn and Company for the pictures from Breasted's "Ancient Times" on page 67; "Agriculture for Beginners" on page 47; Bergen's "Foundation of Botany" on pages 49, 190, and 197; Bergen's "Elements of Botany" on pages 193 and 195; Beal's "Seed Dispersal" on page 51.

U. S. Geological Survey for the pictures on pages 21, 22, 23, 30, 31, and 59.

New York Zoological Society for the pictures on pages 145, 159, and 216.

School Arts Magazine for the picture on page 221.

U. S. Department of Agriculture for the pictures on pages 125 and 189.

American Museum of Natural History for the pictures on pages 20, 24, 26, 139, and 162.

Cassell and Company for the pictures from "Popular History of Animals" on pages 118, 177, 179, and 217; "Popular Science" on page 242.

Hutchinson for the pictures from "Marvels of the Universe" on pages 92, 101, 103, 141, 169, and 173; "Marvels of Insect Life" on page 211.

The Dunham Company for the picture on page 45.

International Harvester Company for the picture on page 199.

Northern Pacific Railway for the pictures on pages 235 and 237.

It will be understood, as stated in the preface, that, like "The Strange Adventures of a Pebble," this is an autobiography. In other words, it is the grain of dust itself that tells the story of the life of the soil of which it is a part.