October 8, 1900] 



SCIENCE 



483 



peculiarities are here included. On the other 

 hand albinism and alkaptonuria are recessive 

 in heredity. 



The next two chapters deal with exceptions, 

 real or apparent, to Mendel's law, a most 

 profitable field for students of heredity to 

 cultivate ; and the last two chapters of Part I. 

 deal with the new light shed on biological con- 

 ceptions by Mendelian discoveries and the 

 practical application of Mendelian principles. 

 The sociological application made, which will 

 be of general interest, is stated concisely thus : 



To the naturalist it is evident that while elimi- 

 nation of the hopelessly unfit is a reasonable and 

 prudent policy for society to adopt, any attempt 

 to distinguish certain strains as superior, and to 

 give special encouragement to them would prob- 

 ably fail to accomplish the object proposed, and 

 must certainly be unsafe. 



This is a conclusion both democratic and 

 sensible, it would seem. 



Part II. contains a biographical notice of 

 Mendel, and a translation of Mendel's two 

 published papers on hybridization, together 

 with a very complete bibliography, an index of 

 subjects and one of authors. 



The book as a whole will be quite indispen- 

 sable to the student of heredity; the general 

 reader will find in it much of absorbing inter- 

 est, although parts will be found too technical 

 for him to follow readily, unless he too wiU 

 become, as he will be tempted to become, a 

 student of heredity. 



W. E. Castle 



Hints for Crystal Drawing. By Margaret 

 Reeks, with preface by Dr. John W. Evans, 

 Imperial College of Science and Technol- 

 ogy, London. Longmans, Green and Co. 

 1908. 



The accurate construction of crystal figures 

 usually offers considerable difBculty to the be- 

 ginner and it was with a view of eliminating 

 some of these difficulties as well as adding a 

 few short-cut methods that this book of 148 

 pages with its 44 plates of drawings was pub- 

 lished. 



Of the various types of projections used by 

 the mineralogist the one known as the clino- 



graphic projection is now usually employed 

 and it is this projection which is chiefly con- 

 sidered. This is discussed in chapter I. 



Chapters II. to IX., or fifty pages of the 

 book, are devoted to directions for the drawing 

 of crystals of the cubic system. The first 

 three classes of this system are treated quite 

 thoroughly and the plates illustrating a few 

 of the common combinations aid the student 

 in following the directions given. The tetra- 

 gonal system is discussed in ten pages, the 

 hexagonal in twenty, the orthorhombic in 

 fourteen, and the monoclinic and triclinic in 

 fourteen and nine, respectively, while the last 

 eighteen pages are devoted to a consideration 

 of twinned crystals. 



In the construction of the axial crosses as 

 well as in the drawing of the more complicated 

 forms, the orthographic plan is first drawn 

 and by dropping vertical projectors the cor- 

 responding points on the clinographic projec- 

 tion are located. This is a decided help to 

 the beginner in pointing out the relationship 

 existing between the two types of projections 

 as well as for locating various points in the 

 drawing itself. 



But the text is not entirely free from criti- 

 cism. The treatment throughout is from the 

 standpoint of an experienced draftsman rather 

 than from that of a skilled crystallographer. 

 A few examples will make this point clear. 



In the drawing of the tetragonal trisocta- 

 hedron 5 211 J (Fig. 1, p. 29) the intersection 

 line P, 3 between the faces designated by 11. 

 and m. does not check with one found by the 

 intersection of the two planes indicated. In 

 Fig. 1, p. 35, the location of the point X can 

 hardly be considered as accurate. The draw- 

 ing of the tetragonal bisphenoid (Fig. 4, p. 65) 

 is incorrect, for its edges should be parallel to 

 lines joining the ends of the crystallographic 

 axes. In the figure on page 79 the crystallo- 

 graphic axes are poorly drawn. 



In all of the above-mentioned instances the 

 general direction of the lines is correct, but 

 carelessness in construction is clearly evident. 

 This is to be regretted, for in a treatise on 

 crystal drawing the figures should by all 

 means be accurate. How can a student be 



