Apeh, 23, 1909] 



SCIENCE 



667 



this phase of crystallograpliy in English and 

 American text-books', and in those in whieh 

 the subjects are treated at all the discussion is 

 so poorly developed as to be practically value- 

 less for teaching purposes. 



While the elements of physical crystallo- 

 graphy are merely touched upon in the vol- 

 ume under review, the development of the dis- 

 cussion is logical and connected, and at every 

 step the correlation between physical and geo- 

 metrical symmetry is emphasized. 



The most notable advance made in this new 

 edition, however, is in the chapter dealing 

 with the relations between the physical prop- 

 erties of crystals and their chemical compo- 

 sition. This portion of the book now occupies 

 26 pages, whereas in the earlier edition it 

 occupied only 11 pages. Morphotropism, 

 homomorphism, isomorphism, eutropism, poly- 

 morphism and isopolymorphism are illustrated 

 by tables of substances exhibiting these prop- 

 erties, and the terms are explained in suffi- 

 cient detail to serve the purpose of introducing 

 the student into the fascinating field of chem- 

 ical crystallography. 



In all respects the volume will serve as an 

 excellent text-book in elementary courses in 

 crystallography. It is more comprehensive 

 than the usual text-book pretending to deal 

 vdth the subject, as it covers the field in all its 

 aspects. The student is shown that crystals 

 are not merely bodies possessing character- 

 istic forms, but that they are bodies which also 

 possess characteristic physical properties, 

 and that such a close relationship exists be- 

 tween their geometrical, their physical and 

 their chemical properties that these characters 

 must be regarded as being connected genetic- 

 ally. That crystallography is a rational 

 science and not merely a descriptive one is 

 the impression left by the reading of the 

 book. It is an impression to be greatly de- 

 sired of American students, who are too apt to 

 look upon crystals from the geometrical stand- 

 point only. 



The objectionable feature of the book is its 

 lack of references. While this omission may 

 be argued as possibly on the whole desirable 

 in most elementary science text-books, in a 

 text-book on general crystallography the omis- 



sion is extremely unfortunate. The literature 

 of physical crystallography is so widely scat- 

 tered that a guide to the most important 

 articles in this branch of the subject would 

 certainly be convenient to the user of the vol- 

 ume. To advanced students — and that is the 

 class to which Dr. Linck's book will most 

 appeal, in America at least — a guide is abso- 

 lutely necessary if the study is to be followed 

 with any seriousness. It is to be hoped that 

 in the next edition the author will insert at 

 least a few references which will indicate 

 where the most important discussions in 

 physical and chemical crystallography may be 

 found. 



W. S. Baylet 



The Cell as the Unit of Life. By the late 

 Allan Macfadyen, M.D., B.Sc. Edited by 

 E. Tanner Hewlett, M.D., etc. Pp. 381 

 and biographical notice. London, J. and 

 A. Churchill; Philadelphia, P. Blakiston's 

 Son & Co. 1908. $3.00 net 

 The lectures brought together in this vol- 

 ume were delivered by the late Dr. Allan 

 Macfadyen at the Royal Institution, London, 

 during the years 1899-1902, and have been 

 edited and published by Professor Hewlett as 

 offering " some memento of a life full of 

 promise and cut off all too soon." The diffi- 

 cult task, undertaken con amore, has been 

 well performed by the editor, and a very read- 

 able and acceptable, although from its very 

 nature somewhat out-of-date, " introduction 

 to biology " lies before us. 



The work is divided into sections, the first 

 of which, under the caption The Cell as the 

 Unit of Life, consists of five lectures on rather 

 elementary biology in which a captious critic 

 might find abundant material to feed his 

 flame; if a morphologist he would take excep- 

 tion to such slips as that which speaks of the 

 "Polar Body or Centrosome" (p. 5Y), or if a 

 protozoologist to false impressions given by 

 statements such as that on page 79 to the 

 effect that always in feeding, "the Amceba 

 seeks out and selects the alga cell." The sec- 

 ond section, under the heading Cellular Physi- 

 ology, is misleading in that little or nothing 

 is said about physiology of the cell, the lee- 



