MIKROSKOPISCHES PRAKTIKUM 293 



I. Imviobiles. — Diatoms incapable of spontaneous movement. 

 Conjugation unknown (perhaps inexistent), or possibly by the 

 fusion of microspores. 



II. Mobiles. — Diatoms which exhibit spontaneous movements. 

 Conjugation known in all the families. 



The author gives a detailed classification of all the genera of 

 the "Immobiles" and of the first section of the "Mobiles" 

 (Eunotieae, Epithemieae, Nitzschiese, and Suriralleae), and discusses 

 the various groups from an evolutionary standpoint. It is an 

 excellent contribution to the literature on Diatoms. 



G. S. West. 



Mikroskopisches Praktikuin filr Systematische Botanik. (I. Angio- 

 spermae.) Von Professor Dr. M. Mobius. Sammlung Natur- 

 wissenschaftlicher Praktiker. Band I. Figs. 1-150. Berlin : 

 Gebriider Borntraeger. Pp. i-viii, 1-216. Price 6 M. 80 Pf. 



This valuable addition to the literature of practical botany 

 begins with a brief but useful introduction, containing excellent 

 hints on the dissection of flowers and the making of permanent 

 preparations. The " Systematischen Teil" then opens with a 

 general account of the Angiosperm and the distinction between 

 the Monocotyledon and the Dicotyledon ; the floral dissection of 

 Capsella Bursa-pastoris L. is exhibited in detail as an example. 



The main subject of the book is an account of the chief floral 

 characteristics of the principal families of Angiosperms. The 

 system followed is that of Warming : families — one hundred and 

 forty-four in all — are selected from every cohort for the purpose 

 of practical investigation. 



The abundant figures, clear, bold, and original, all illustrating 

 salient and difficult points revealed in the course of dissection, are 

 excellent, and the mere act of glancing through them yields no 

 little instruction ; all the principal families are represented. In 

 some cases — for example, Grasses, Scitaminece — we might wish 

 for more illustrations to aid the student in the exhibition and 

 understanding of the difficult and minute details of such families. 

 At the same time the book does not pretend to be a complete text- 

 book of systematic botany, but, as hinted in the preface, is in- 

 tended to serve as a practical guide, to be used in conjunction with 

 any of the standard works on systematics. 



The " floral diagram," the darUng of all the text-books since 

 Eichler set the fashion, is conspicuous by its absence ; and syste- 

 matic botany is taught as a living subject. Organs are figured as 

 they actually appear, and special difficulties are conscientiously 

 dealt with. Herein lies the originality of the book and its 

 undoubted value to students of every class, for how many have 

 not been confounded by details of structure and arrangement of 

 ovary, ovules, embryo, endosperm, and the like, often so minute 

 and yet so fundamentally important ? In dealing with difficulties 

 of this kind, the student has had recourse too often to the 

 theoretical floral diagram and its mechanical commission to 

 memory ; but this book is admirably calculated to stimulate him 



