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THE POPULAR SCIENCE MONTHLY. 



The Life-History of Our Planet. By 

 William D. Gunning. Illustrated by 

 Mary Gunning. Chicago : W. B. Keen, 

 Cooke k Co. Pp. 368. Price, $2. 



To the obvious criticism that so large a 

 subject as " The Life-History of Our Planet " 

 cannot very well be compressed within the 

 limits of a handy volume like the present, 

 it may be fairly replied that an outliue of 

 such a history, giving its leading features 

 and more impressive aspects, is altogether 

 a practicable thing. Prof. Gunning has 

 shown this in the preparation of the vol- 

 ume before us, which certainly presents 

 the leading historic aspects of terrestrial 

 life in a manner that is highly instructive. 

 The book is a successful attempt to popu- 

 larize a great branch of science without 

 sacrificing or cheapening it. Although the 

 author deals with many new facts which 

 are usually wrapped in an obscure termi- 

 nology, he yet presents them in such a plain, 

 familiar, direct, common-sense manner as 

 to be understood by all readers who have 

 the slightest interest in the subject. Well 

 experienced in public teaching, he neither 

 overshoots the average capacity nor wearies 

 it by dwelling too long upon the minu- 

 tia? of his topics. He, moreover, gains 

 much in compression of statement by giving 

 prominent attention to the general views 

 and truths of his subject, rather than to its 

 interminable particulars. His mode of ex- 

 position is indicated in the following prefa- 

 tory passage: "Facts do not enlarge the 

 mind unless they are fertilized by princi- 

 ples. Our aim in the preparation of this 

 volume has been to conduct the reader 

 through methods to results. The leading 

 types of life which have possessed the earth 

 from age to age, he will find described and 

 delineated. He will find the more signifi- 

 cant types reconstructed, part by part, with 

 so little of the phraseology of comparative 

 anatomy that his mind, it is hoped, will 

 traverse the methods and make them his 

 own." The aim here proposed has been 

 well attained, and, by treating his subject 

 in the light of the great principles of unity, 

 correlation, progressive unfolding, and in- 

 terconnection with the course of physical 

 Nature, the author has invested the great 

 historical problem of the earth's past life 

 with unusual interest and attractiveness. 

 We should like to quote copiously from 



" The Life-History of Our Planet," but have 

 not room to do so. The following passage 

 is representative, and illustrates the writ- 

 er's clear and pointed way of picturing 

 phenomena before the minds of his readers : 

 " In 1818 Traill dissected one of the higher apes, 

 and found in the region of the thigh a muscle which 

 he thought had no representative in man. He named 

 it the scansorius, or ' climbing ' muscle. Late dis- 

 sections have shown Traill to have been in error. 

 Its homologue in man is found to be the little mus- 

 cle called gluteus minimus. What is the meaning 

 of this little useless muscle in man, unless it is the 

 atrophied descendant of a real scansorius ? In that 

 man-like ape, the orang, Dr. Barnard, of Cornell, 

 has found a muscle whose homologue has never 

 been found in man. In the orang it occurs as a ves- 

 tige. It has almost faded out. It occurs in the 

 lower apes and in the half-apes, but always as a ves- 

 tige, having no functional value. It appears again 

 in the opossum, but no longer as a vestige. Thus, 

 a muscle which is obsolete in man, almost obsolete 

 in the higher apes, less aborted in the lower apes, 

 still less aborted in the half-apes, is found in the 

 opossum with its functional value." 



The first chapter of the book is devoted 

 to what may be called the preliminary phys- 

 ics and geology of the subject. The second, 

 third, and fourth, treat of the rise and evo- 

 lution of organic types, and the fifth is de- 

 voted to the question of glaciers and the 

 part they have played in the history of the 

 earth's surface. This is an excellent chap- 

 ter and gives a very clear account of that 

 most difficult matter for popular explana- 

 tionthe relation of the precession of the 

 equinoxes, and the secular variations of the 

 earth's orbit to the glacial periods. The 

 development of animals, the appearance 

 upon earth of man, his antiquity and mi- 

 grations, and the origin and derivation of 

 races, occupy the remaining four chapters 

 of the work, which may be regarded as a 

 kind of preliminary text-book of philosoph- 

 ical biology. It is neatly and fully illus- 

 trated, and deserves to have a wide circula- 

 tion. 



The American Library Journal. (Month- 

 ly.) Managing Editor, Melvil Dewey. 

 New York: F. Leypoldt. Yearly sub- 

 scription, $5. 



More than usual interest has been taken 

 in the public libraries during the last year. 

 The recent conference at Philadelphia, and 

 the Report of the Educational Bureau at 

 Washington, have now been supplemented 

 by the Library Journal. Its plan is to 

 cover the entire field of library and biblio- 



