April 7, 1916] 



SCIENCE 



501 



an explanation and substitutes for Paleogene 

 used throughout the book for the lower Ter- 

 tiary the term Eogenic. 



Hertet W. Shimer, 

 Frederic H. Lahee 

 Massachusetts Institute op Technology 



Modes of Research in Genetics. By Eaymond 

 Pearl, Biologist of the Maine Agricultural 

 Experiment Station. The Macmillan Com- 

 pany. Pp. 182. Price $1.25. 

 In this book Professor Pearl has paused in 

 the midst of his prolific and fruitful researches 

 to put together in logical sequence around the 

 central theme of methodology in genetics the 

 substance of several of his recent papers and 

 addresses. 



There has been need enough for such a clear- 

 cut analysis of the possibilities and limitations 

 of the various methods now being utilized by 

 workers in the expanding field of genetics and 

 the author has performed this service most 

 acceptably. 



It is particularly gratifying to have a sane 

 non-controversial evaluation of the much 

 abused biometric method by one who is a past- 

 master in biometry and is at the same time a 

 biologist of notable attainment. It must be 

 confessed that biometry of late years has 

 rather needed a champion since non-mathe- 

 matical biologists while admiring the magic of 

 the biometrician, are often haunted with seri- 

 ous doubts about the value of the conclusions 

 sometimes reached by this mode of investiga- 

 tion. 



Although biometrics receives the most ex- 

 tended consideration of any method there is 

 a comprehensive analysis of three other modes 

 of research, namely, the Mendelian, the cyto- 

 logieal and the embryological. 



The next to the last, and the longest, chapter 

 diverges into a somewhat technical treatment 

 of the problem of inbreeding. Here the aver- 

 age lay reader is likely to ride through a 

 tunnel with only intermittent glimpses of the 

 light, but he is sure to emerge into broad day- 

 light in the fijial chapter, which is upon 

 " Genetics and Breeding," and feel well repaid 

 for his journey. For any one engaged, or 

 even interested, in genetic research Dr. Pearl's 



book will prove a most welcome and illumi- 

 nating volume. 



It is obvious that " Table III." on page 111 

 should read Table I. H. E. Walter 



An Introduction to the Study of Variahle 



Stars. By Caroline E. Furness, Ph.D. 



Boston, Houghton Mifflin Company. 1915. 



Pp. 327. $1.75 net. 



It is rather remarkable that no comprehen- 

 sive work on variable stars had previously ap- 

 peared in any language, though Hagen's ex- 

 tensive treatise, " Die veranderlichen Sterne," 

 of which the first two parts have already been 

 published, would soon have been completed 

 had the war not delayed it. It is very timely 

 in view of the great expansion in the past few 

 years, not only in the observations of variable 

 stars, but more especially in the deductions 

 from their phenomena. Cosmic theories have 

 drawn heavily on these phenomena, and seem 

 likely to gain still more from further study. 



Following the introductory chapter the 

 work falls naturally into four divisions. 



1. The equipment of the observer; maps, 

 charts, catalogues: Chapters II. to V. 



2. Photometry of variable stars; visual, 

 photographic, photo-electric: Chapters VT. 

 to VIII. 



3. Eeduction of the observations; light- 

 scale, light-curves, elements and predictions: 

 Chapters IX. to XI. 



4. Deductions from these data; eclipsing 

 and long-period variables, statistics, observ- 

 ing hints, tables: Chapters XII. to XV. 



That the book is written from the stand- 

 point of the teacher is well evidenced by the 

 care taken to explain the fundamental ideas 

 of each chapter. For example, the elements of 

 spectrum analysis and radial velocity are 

 given in considerable detail, a precaution very 

 necessary to clarify the hazy ideas held by 

 young students of spectroscopy. The prin- 

 ciples underlying the photometric instruments 

 are set forth in detail, especially the photo- 

 electric appliances which have so recently en- 

 tered the field of stellar photometry. A hu- 

 man interest is added by brief biographical 

 sketches of some of the older great astron- 



