238 NOTICES OF BOOKS. 



continue as a larval form during the rigours of a Danish winter. 

 Thirteen new species were added to the Danish fauna, making 

 twenty-five in all. 



It is of great interest to note that this valuable memoir 

 issued under Danish authority is yet written in English. The 

 plates are very beautifully produced and are from careful original 

 dra\vdngs by the author. To anyone engaged on similar researches 

 on a special group of insects we can cordially recommend this 

 monograph as an example to be followed in the presentation of his 

 results. 



The Elements of Vegetable Histology. By 0. W. Ballard, 

 pp. xiv + 246 + 75 figs, in text. 8 X 5-| inches. (New 

 York : John Wesley & Sons Inc. London : Chapman Hall, 

 Ltd., 1921. Price 18s. net.) 



The author of the above book is Associate Professor of 

 Materia Medica and Director of the Microscopical Laboratory 

 at Columbia University, and it embodies his experience gained 

 as a teacher of the needs of the student who intends later to 

 specialise in the micro-analysis of foods. The volume is intended 

 for the beginner and to provide a practical laboratory guide in the 

 subject. In many instances details have been omitted in order 

 to avoid confusion in the mind of the student, a knowledge of 

 general principles as a groimdwork for further study being aimed 

 at. The importance of laboratory work is properly emphasised, 

 as the personal equation is of much importance in the right 

 interpretation of findings in the micro-analysis of foods. There 

 are chapters devoted to the preparation of specimens and the 

 chemical reaction of plant tissue, of microscopic technique 

 and the use of the microscope. The chapters devoted to Vegetable 

 Histology are arranged under the headings of the various tissues 

 described and under root, stem, leaf, flower, fruit and seed 

 structures. In each, practical details are given for the prepara- 

 tion and examination of fresh and stained material. The 

 chapters describing root and stem structure are particularly 

 praiseworthy in the way a very intricate subject is dealt with. 

 Numerous illustrations are introduced from original drawings, 

 which are intended to show the important details to be noted by 

 the student while examining the material under observation. 



