THE POPULAR SCIENCE MONTHLY. 



further than the present state of our knowl- 

 edge warrants. The group Brachiopoda owes 

 its chief interest to the immense variety and 

 great antiquity of its fossil forms. There 

 are at the present time only about one hun- 

 dred and twenty extant species. The study 

 of the mollusca occupies 460 pages, the re- 

 mainder of the work being devoted to the 

 brachiopods. The book is intended appar- 

 ently as a student's manual. The description 

 is clearly written and contains considerable 

 historical narrative and many good illustra- 

 tions. 



Mr. Clodd justifies his Primer of Evolu- 

 tion* an abridgment of his Story of Crea- 

 tion, by the reception which the larger work 

 received, and the necessity for putting the 

 material into a condensed and inexpensive 

 form in order to reach the general reader. 

 The first portion is descriptive : matter and 

 motion, from the philosophical standpoint ; 

 the distribution of matter and the solar sys- 

 tem; and finally two long chapters on the 

 past life history of the earth and present life 

 forms, compose Part I. Part II, the explana- 

 tory portion, has chapters on the becoming 

 and growth of the universe, the origin of 

 life and life forms, on the origin of species, 

 and social evolution. The book is written in 

 a popular style, and seems an improvement 

 on its more bulky predecessor. 



The high disciplinary value of the study 

 of psychology, which gives a scientific basis 

 to education and lifts it out of empiricism, is 

 distinctly shown hi the volume before us.f 

 The authors have pointed out, hi a very in- 

 teresting manner, the application of psychol- 

 ogy to number. They say that the teacher 

 who knows how the mind works in the con- 

 struction of number is prepared to help the 

 child to think number. They take the posi- 

 tion that the normal activity of the mind in 

 constructing number is highly pleasurable. 

 This is confirmed by actual experience and 

 observation of facts hi child-life. There are 

 few children who do not delight in counting, 

 and the fact should be taken advantage of 



* A Primer of Evolution. By Edward Clodd. 

 London and New York: Longmans, Green & Co. 

 Pp. 186. Price, 75 cents. 



t Psychology of Number. By Dr. J. A. Mc- 

 Clellan and Prof. John Dewey. International 

 Education Series. New York: D. Appleton & 

 Co. Pp. 309, 12mo. Price, $1.50. 



by instructors. A sympathetic and compe- 

 tent teacher can interest them so keenly that 

 apparently wonderful results may be ob- 

 tained with but little difficulty. 



The authors speak of how an absolute dis- 

 taste for number is created by faulty meth- 

 ods of teaching, with arrested development as 

 a natural result. They say it is perhaps not 

 too much to affirm that nine tenths of those 

 who dislike arithmetic, or who at least feel 

 that they have no aptitude for mathematics, 

 owe this misfortune to wrong teaching at 

 first. The teacher can readily learn from an 

 intelligent study how to make the work of 

 the schoolroom consistent with the method 

 under which by Nature's teaching the child 

 has already secured some development of the 

 number activity. Beginning with a group, 

 counting, parting, and wholing are all in har- 

 mony with Nature's method, which "promotes 

 the natural exercise of mental function and 

 leads gradually but with ease and certainty to 

 true ideas of number. It minimizes the diffi- 

 culty with which multiplication and division 

 have hitherto been attended, and helps the 

 child to recognize in the dreaded terra incog- 

 nita of fractions a pleasant and familiar land." 



The authors' remarks concerning kinder- 

 garten work are sound and are based upon 

 results that are evident to all. There is a 

 sure and pleasurable way, along the line of 

 least resistance, that may be followed in the 

 kindergarten, with great improvement in the 

 method of preparation for a child's work 

 later. The authors say : " Surely something 

 is lacking, either in the kindergarten as a 

 preparation for the primary school or in the 

 primary school as a continuation of the kin- 

 dergarten, when a child after full training in 

 the kindergarten, together with three years' 

 work in the primary school, is considered 

 able to undertake nothing beyond the ' num- 

 ber twenty.' " They add that under rational 

 and pleasurable training of the number in- 

 stinct in the kindergarten the child ought to 

 be arithmetically strong enough to make 

 immediate acquaintance with the number 

 twenty, and rapidly acquire, if he has not 

 already acquired, a working conception of 

 much larger numbers. 



In the easiest possible manner the authors 

 go on to explain every process of number, 

 and the presentation is such as to interest 

 any one impressed with the necessity of a 



