THE MACMILLAN CO. OF CANADA, Ltd.
TORONTO
Saturn—photographed at the Lowell Observatory
by Mr. E. C. Slipher. September, 1909.
THE EVOLUTION OF WORLDS
BY
PERCIVAL LOWELL, A.B., LL.D.
AUTHOR OF “MARS AND ITS CANALS,” “MARS AS THE ABODE OF LIFE,” ETC.