340 



SCIENCE 



[N. S. Vol. XXV. No. 635 



tions for the chick, teleosts, amphibia and 

 mammalia, and directions for the artificial 

 fecundation and study of the early cleavage 

 of forms permitting it. Chapter XVII. gives 

 the two most generally used methods for the 

 reconstruction of specimens from sections, 

 namely, reconstruction with wax plates and 

 geometrical reconstruction. 



Memoranda are given at the end of each 

 chapter and these are often more interesting 

 to one familiar with the general working of 

 the methods than the procedure for the meth- 

 ods to which the chapter is devoted, for it is 

 in these memoranda that various adaptive 

 modifications of the methods are given, valu- 

 able suggestions as to technique in dissection, 

 the choice of tissues for the purpose in mind, 

 the construction and manipulation of the 

 necessary apparatus, the selection and making 

 up of the reagents required, and, equally im- 

 portant, suggestions as to the most probable 

 causes of failure and the steps in procedure 

 at which special care should be exercised. 

 The substance of the memoranda might, less 

 wisely, have been included in the body of the 

 chapters, but, as the author states, they are, 

 instead, appended to each chapter in order to 

 supply additional information more or less 

 pertinent without obscuring the main features 

 of the methods under consideration. 



Of the appendices, the first is devoted to the 

 construction and discussion of the microscope 

 and the optical principles involved in its use, 

 with directions for its manipulation and an 

 alphabetically arranged list of the more com- 

 monly used microscopical terms and appli- 

 ances. In the second appendix is given a 

 series of formulte well chosen as representing 

 some of the more efficient and frequently used 

 reagents, including fixing and hardening 

 fluids, stains, indifferent fluids, dissociating 

 and decalcifying fluids. After each fluid is 

 noted its peculiar advantages and some of the 

 tissues and purposes to which it is best adapt- 

 ed. The third appendix is a tabulation of a 

 large number of tissues and organs arranged 

 alphabetically in systems with concise direc- 

 tions in appropriate columns for the obtain- 

 ing, fixing and after-treatment of each ; while 

 the fourth appendix is especially devoted to 



directions for the collection and preparation 

 of the various materials necessary for a gen- 

 eral course in zoology. The last appendix 

 consists merely of four conveniently con- 

 structed reference tables of equivalent weights 

 and measures. 



The book is amply illustrated as to the dif- 

 ferent apparatus required and, while one 

 might criticize the prominence with which the 

 names of firms making the apparatus fre- 

 quently stand out in the cuts, a little adver- 

 tising is allowable in exchange for the excel- 

 lence of the cuts used. 



On the whole, the extended scope of the 

 book, together with its conciseness of con- 

 struction and reasonable price, renders it high- 

 ly commendable, and, in my opinion, it will be 

 found useful to a larger number of people 

 than any other book of its kind at present in 

 existence in English. Since each experienced 

 worker in microscopical technique has his own 

 devices of manipulation which work best for 

 him, there are, of course, some instances in 

 which the author's ' steps ' and ' tricks ' may 

 be disputed as being the most efficient. Pro- 

 fessor Guyer modestly recognizes this. How- 

 ever, with such workers, the book will be 

 found full of helpful suggestions, new to 

 many. The general student will find that all 

 the methods recommended will yield good re- 

 sults when the directions are intelligently fol- 

 lowed, and the fact that the author has striven 

 to make the book thoroughly practical: 'to 

 omit everything that is not essential, and, 

 above all, to give definite statements about 

 things,' has resulted in a much-desired brevity 

 of treatment and obviation of bulk. 



Irving Hardesty 

 The University of California 



Recent Progress in the Study of Variation, 

 Heredity and Evolution. By Robert Heath 

 Lock. Pp. 299. London, John Murray. 

 1906. 



At this time when the systematic botanists 

 and zoologists differ greatly in regard to their 

 large number of tissues and organs arranged 

 reader will find the book under review a most 

 useful help in arriving at sensible conclusions. 

 Mr. Lock is well fitted to discuss the subjects 



