Established by Edward L. Youmans APPLETONS' POPULAR SCIENCE MONTHLY EDITED BY WILLIAM JAY YOUMANS VOL. LVI NOVEMBER, 1899, TO APRIL, 1900 NEW YORK D. APPLETON AND COMPANY 1900 COPYRIGHT, 1900, BY D. APPLETON AND COMPANY. [Illustration: EDWARD ORTON.] CONTENTS PAGE THE TRANSPLANTATION OF A RACE. 513 MODERN CITY ROADWAYS. 524 TYPICAL CRIMINALS. 539 A CENTURY OF GEOLOGY. 546 "SALAMANDERS" AND "SALAMANDER" CATS. 556 WHAT MAKES THE TROLLEY CAR GO. 564 A SURVIVAL OF MEDIÆVAL CREDULITY. 577 "RIBBON LIGHTNING." 587 CROSS-EDUCATION. 589 THE MORBID "SENSE OF INJURY." 596 EARLY EXPERIMENTS IN AIR FLIGHT. 603 SKETCH OF EDWARD ORTON. 607 EDITOR'S TABLE. 614 FRAGMENTS OF SCIENCE. 618 MINOR PARAGRAPHS. 622 PUBLICATIONS RECEIVED. 624 APPLETONS' POPULAR SCIENCE MONTHLY. MARCH, 1900. THE TRANSPLANTATION OF A RACE. BY N. S. SHALER, DEAN OF THE SCIENTIFIC SCHOOL OF HARVARD UNIVERSITY.