344 NATURAL SCIENCE. May. 



When a second edition was called for, within three years of the 

 first, the author found it necessary to give his book a more severely 

 practical character. The author then said in his Preface: "One 

 thing has become perfectly clear to me ; the centre of gravity of the 

 book must lie in microscopic technology, and in guidance to scientific 

 observation. This book could not be allowed to grow into a hand- 

 book of vegetable anatomy, but in microtechnical respects it had to 

 reach such a degree of completeness that everybody could find in it what 

 he wanted. I have therefore somewhat restricted the number of 

 examples, while considerably increasing the technical instructions." 

 Now that, after an interval of about ten years, a third edition has 

 appeared, we find that further changes have been made in the same 

 direction. "This time also" says the author (p. xii) "I have 

 diminished the number of plants investigated, in order to give the 

 necessary extension to that task in which the centre of gravity of the 

 work lies, namely microscopic technology." In consequence of this, 

 the book has no doubt become of even greater value to the practical 

 investigator, but it has certainly lost something of its attractiveness 

 for the general botanical reader, for nothing is so unreadable as long 

 descriptions of methods and apparatus. However, a laboratory guide 

 is nothing if not practical, and we have no right to complain if Prof. 

 Strasburger's work, like some highly specialized organism, has become 

 more and more rigidly adapted to the conditions of its existence. 

 The book has grown, since the last edition, from 685 to 739 

 pages, but the increase is entirely in the technological Introduction 

 and in the indices ; the actual descriptive text has somewhat 

 diminished. 



The great feature of the Introduction is the prominence now 

 given to the microtome and methods connected with its use. Since 

 the second edition appeared, the microtome, as the author says (p. xi) 

 has made its way into every institution which keeps up with the 

 progress of the microscopic art. " The knowledge how to use it, must 

 now be acquired by every body who wishes to work with success in 

 the province of histology " (p. 31). English botanists have taken at 

 least their full share in this important change, which in many cases 

 has raised section-cutting from the region of chance into that of 

 certainty. A number of forms of microtome are described and illus- 

 trated — among them our old friend the " Cambridge rocker," an 

 imitation of which is now, it appears, " made in Germany." The 

 part of the Introduction relating to the microscope and other 

 optical apparatus has also undergone a thorough revision, in accord- 

 ance with the present position of microscopy. 



The arrangement of the contents of the 32 chapters on " Pensa " 

 which form the main part of the text, has been somewhat modified, 

 especially in the anatomical part, so as to give the whole course a 

 more logical order. The headings of the chapters have been extended, 

 in order that they may afford a complete idea of the contents of each, 

 and of the material required. The large-print paragraphs contain all 

 that is needed by the ordinary student, while a botanist who has worked 

 through the whole, will be qualified for any histological investigation. 



The author has evidently spent a vast amount of labour on this 

 edition, for the latest results of research have been everywhere 

 introduced, and usually tested by the personal observations of the 

 writer. For example, the development of the starch-grains is 

 now described in Pellionia Daveauana ; the enzyme-sacs of Cruciferae are 

 explained in accordance with Guignard's researches ; Pvotosiphon is 

 separated from Botvydmm, as the result of quite recent work by Klebs, 



