“Dr. Yerkes’ book is a most interesting example of modern laboratory methods and can be read with profit by any one, on account of the accurate methods of observation and careful deductive reasoning which it shows. An elaborate, painstaking system of experiments was carried on with over 400 mice, with the object of determining muscular coördination, structural peculiarities, strength of the special sense organs, habit formation, educability, and strength of memory of these little animals. Some experiments were also undertaken along the line of inherited peculiarities.... The work is really only a preliminary study, but it will be read with much interest by all students of comparative psychology.”—_Journal of American Medical Association._ The Animal Mind By MARGARET FLOY WASHBURN, Ph.D., Professor of Philosophy, Vassar College _Cloth, 12mo, 333 pages, $1.60 net_ “As the author points out, the title of this book might more appropriately have been ‘The Animal Mind Deduced from Experimental Evidence,’ for the facts here set forth are very largely the results of the experimental method in comparative psychology. The mass of experimental material that has been accumulated from the researches of physiologists and psychologists is already great, but is also for the most part inaccessible to the ordinary student, being widely scattered and to a considerable extent published in the journals of specialists, which the average college library does not contain. Hence the usefulness of the present ... interesting work.”—_New York Sun._ The Series is Published by THE MACMILLAN COMPANY 64-66 Fifth Avenue, New York OTHER NATURE BOOKS Four-Footed Americans _And their Kin_ By MABEL OSGOOD WRIGHT. Edited by FRANK M. CHAPMAN. Illustrated by ERNEST SETON THOMPSON _Cloth, 12mo, $1.50 net; School Library Edition, 50 cents net_ “It deserves commendation for its fascinating style, and for the fund of information which it contains regarding the familiar and many unfamiliar animals of this country. It is an ideal book for children, and doubtless older folk will find in its pages much of interest.”—_The Dial._ “Books like this are cups of delight to wide-awake and inquisitive girls and boys. Here is a gossipy history of American quadrupeds, bright, entertaining, and thoroughly instructive. The text, by Mrs. Wright, has all the fascination that distinguishes her other outdoor books.”—_The Independent._ Citizen Bird _Scenes from Bird Life in Plain English for a Beginner_ By MABEL O. WRIGHT and Dr. ELLIOTT COUES. Profusely Illustrated by LOUIS AGASSIZ FUERTES _Cloth, 12mo, $1.50 net; School Library Edition, 50 cents net_