V 1 1 1 



Supplement to "Nature" November 6, 1902. 



can hardly hope even to scratch the surface, much less 

 seriously to cultivate any part of it. He certainly will 

 not receive that kind of training which goes to form a 

 critical judgment on facts and inferences, although the 

 imparting of this ought to be one of the chief objects of 

 all higher education, whether of a scientific character or 

 otherwise. It is this conviction that obliges us to confess 

 that we think Prof. Campbell has set himself a difficult — 

 if not, indeed, an impossible — task, and we cannot avoid 

 a feeling of regret that he should have decided at all 

 " to present in as compact a form as possible an outline 

 of the essentials of modern botany.'' It is not that the 

 book is not good of its kind — of which many already exist 

 — but we doubt the intrinsic usefulness of its aims, even 

 admitting these to have been realised. At any rate, the 

 results, in so far as taxonomy, morphology and physiology 

 are concerned, are certainly disappointing. The inform- 

 ation given is of necessity ofttimes scrappy, and especially 

 is this the case in the chapters dealing with classification. 

 The student would scarcely find any other use for them 

 than as mere statements to be learnt by heart. He would 

 assuredly experience frequent difficulty in ascertaining 

 on what rational basis the systems of classification them- 

 selves are erected. 



By far the best part of the book is that devoted to a 

 consideration of the geological and geographical dis- 

 tribution of plants. It contains much excellent matter, 

 and may be heartily commended to students. Perhaps 

 one might be inclined to take exception to a statement 

 here and there, as, for example, the assertion that man is 

 a very necessary agent in effecting the wide tropical 

 distribution of the coconut. 



But if our judgment on the book regarded as a whole 

 appears to be a somewhat adverse one, this is not clue 

 to the way in which Prof. Campbell has executed his self- 

 imposed task ; our quarrel lies rather with the nature of 

 the task itseK. Nevertheless, the book, considered as a 

 work of reference rather than as a text-book for the 

 average student, may probably prove decidedly uselul. 

 It appears to contain very few errors, and the figures are 

 numerous and, on the whole, excellent. 



EMBRYOLOGY OF THE LOWER 



VERTEBRATES. 



Lehrbuch dcr verghichenden Entwickelungsgeschickte tier 



niederen Wirbeltiere, in systematischer Reihenfolge 



und mil Berticksichtigung der experimentellen Embryo- 



logie bearbeitet. By Prof. Heinrich Ernst Ziegler. Pp. 



xii + 366 ; 327 figures and a coloured plate. (Jena : 



Gustav Fischer, 1902.) Price 10 marks. 



"TPHIS volume marks the tendency to increased 



J- specialisation in text-books, for it is an embryology 



of the lower Vertebrates. It also fills an obvious gap, 



for Balfour's classic work is acknowledged to be out of 



date, the large cooperative treatise now being edited 



by O. Hertwig is on an altogether bigger scale and 



different plan, the works of Bonnet, Kollman, Minot 



and O. Schultze deal with man or with mammals, and 



even in the well-known text-books of Hertwig and 



Milnes Marshall the lower Vertebrates are somewhat 



overshadowed by their successors, the Amniota. Thus 



there is room for Prof. Ziegler's volume, at which he has 



NO. 1723, VOL. 67] 



laboured, he tells us, for a dozen years. The result 

 seems to us to justify his carefulness. 



We would first remark on some of the distinctive 

 features of the book as a whole, (1) Most attention is 

 paid to the earlier stages in development ; thus gastrula- 

 tion and germ-layer-formation have more space than 

 organogenesis. (2) While prominence is given to mor- 

 phological ideas, the salt of which does not lose its savour, 

 much attention has been paid to the trustworthy results 

 of recent work in experimental embryology. (3) In 

 regard to some of the more important moot points, the 

 author gives a just statement of conflicting interpreta- 

 tions ; in regard to others, he frankly states that he has 

 given prominence to the view which his own investiga- 

 tions have led him to confirm or to formulate. (4) Very 

 useful to the student are the numerous foot-notes which 

 define the more difficult technical terms as they occur in 

 the text, and sometimes include little side excursions of 

 pleasant interest. (5) The bibliography at the end of 

 each chapter is very full, but it has been put through a 

 sieve, and, to avoid needless repetition, much of the 

 older literature (given in Balfour's " Embryology," &c.) 

 has been omitted. (6) There is an illustration on almost 

 every page, and while there are many old friends (only 

 eighty-seven from other text-books), seventy-four are 

 Ziegler's own. 



The first chapter gives recipes for preservation, and 

 hints as to sectioning, model-reconstruction (of which the 

 author's father was one of the pioneers), photography and 

 the like. In the second chapter, there is a general sketch 

 of the development of Vertebrates, with an exposition of 

 technical terms. Perhaps the most interesting section is 

 that in which the developmental processes in the founda- 

 tion of organs are summarised : — cell-movements ; dif- 

 ferentiation ; unequal growth ; curvature, folding and 

 tube-formation ; evagination and invagination, formation 

 of villi and diverticula ; proliferation ; and splitting. 

 Emphasis is laid on the familiar but difficult distinction 

 between palingenctic and ccenogenetic processes, and 

 it is further noted that complications arise by what may 

 be called temporal and spatial shuntings (1 leterochronien 

 und Heterotopien), when an organ of increasing im- 

 portance appears more and more precociously, e.g. the 

 heart in Amniota, and when the seat of formation is 

 altered, as in the shifting of the Blut-Anlagen from 

 mesoderm to endoderm in Amphibians. 



The succeeding chapters, forming the body of the 

 book, deal with the lancelets, Cyclostomes, Selachians, 

 Ganoids, Teleosts, Dipnoans, Amphibians and Gym- 

 nophiona ; and the last chapter, on the Amniota, shows 

 how the development of the lower Vertebrates sheds light 

 upon that of the higher. We find these chapters lucid 

 and interesting ; the material is freshened, if not as yet 

 greatly illuminated, by the incorporation of the experi- 

 mental results ; the notes (at the head of important 

 sections) on the most essential memoirs and on demon- 

 stration-material will be of service to other teachers ; 

 and there is a fresh, stimulating atmosphere about the 

 whole book. In evidence of its up-to-dateness, we may 

 note that it includes the work of Dean on Bdellostoma, 

 Graham Kerr on Lepidosiren, Brauer on Hypogeophis, 

 and so on. 



A brief indication may now be given of the author's 



