4 22 



POPULAR SCIENCE MONTHLY. 



GENEEAL NOTICES. 



SINCE the establishment of the cell theory 

 by Schieden and Schwann in 1838-'40, it 

 has been recognized that a clear understand- 

 ing of the processes which go on in the 

 body, both physiological and pathological, 

 and of their relations to parent and offspring, 

 can only be obtained through a study of the 

 cell. This study has thrown new light on 

 many obscure points in heredity, and has 

 revolutionized our theories of the " vital 

 process." Such books as the one before us * 

 are the cause as well as the result of such 

 investigations through their attractiveness 

 stimulating the student to renewed effort. 

 This one is a series of micro-photographs 

 taken from sections of the .eggs of the sea 

 urchin and so arranged as to illustrate the 

 principal phenomena in the fertilization and 

 early development of the animal egg. The 

 photographic reproductions are accompanied 

 by a critical description and drawings illus- 

 trating every stage, and are preceded by a 

 simple introductory account of the recent 

 history and growth of the science. The re- 

 fined histological technique and the manual 

 skill necessary for original work of this qual- 

 ity are rarely at the command of the stu- 

 dent. He has to get his knowledge from 

 text-books, hence an accurate reproduction 

 of the various specimens is quite essential. 

 The photographs in this work were taken 

 with especial care, not retouched, and repro- 

 duced in the prints as closely as possible. 

 The book is unique in containing the first 

 satisfactory series of photographic representa- 

 tions of the early history of the ovum. Prof. 

 Wilson is to be congratulated both as to his 

 own work and in having so skillful a col- 

 laborator as Dr. Learning. 



The author of this book,f who is the in- 

 structor in physics in the English High 

 School of Boston, has been before the public 

 as an author of text-books on physics for 



* Atlas of the Fertilization and Karyokinesis 

 of the Ovum. By Edmund B. Wilson, Ph. D., 

 with the co-operation of Edward Learning, M. D. 

 Pp. 32, quarto. New York. and London: Mac- 

 millan & Co. Price, $4 ; 17*. 



t The Principles of Phyeics. By Alfred P. 

 Gage. Pp. 634, 12mo. Boston, U. S. A., and 

 London : Ginn & Co. Price, $1.55. 



the past thirteen years. His latest produc- 

 tion is characterized by a fullness which he 

 intends to be a protest against " smaller 

 books," " cheaper books," and " primers of 

 science." " Education in physics," he affirms, 

 " implies the presentation of the great truths 

 of that science in their unmutilated form, 

 the indication of their relations to one another, 

 and the furnishing the student an oppor- 

 tunity of observing and exercising the logical 

 processes that have led to the discovery of 

 those truths. Any text-book that aims to 

 introduce the student to a study of such im- 

 portance and such inexhaustible possibilities 

 should not lose sight of this truth and en- 

 courage mere dilettanttism." Accordingly, 

 he supplements his statement of physical 

 laws by a store of concrete applications and 

 other illustrative matter. The book contains 

 a " high-school " course and an " advanced " 

 course, the latter comprising the former and 

 additional matter distinguished by indenting. 

 Some illustrative experiments are given, but 

 the work is not intended to serve as a labo- 

 ratory manual. A considerable number of 

 problems and exercises have been inserted, a 

 key to which is furnished to instructors. 

 There are nearly five hundred illustrations, 

 and a colored chart showing spectra and 

 combinations of colors. 



An experimental laboratory has, with the 

 growth of modern methods of teaching, be- 

 come almost a necessity in the study of bot- 

 any. The book before us * is designed to aid 

 and direct experimental study. As to the 

 scope of his book the author says : " With 

 the rapid advance of investigation it is 

 next to impossible that an elementary lab- 

 oratory manual should include the latest 

 results, especially when the essential points 

 of many of them may yet be in contro- 

 versy, and need the critical treatment which 

 is certainly not within the province of a 

 work of this character. In the hands of 

 an instructor in touch with current botanical 

 thought such deficiencies are easily supplied. 

 The present work consists of a series of ex- 



* Experimental Plant Physiology. By D. T. 

 Macdougal. Pp. 85, 8vo. Ne.v York: Henry 

 Holt & Co. Teachers' price, $1. 



