176 



NATURE 



[October 7, 1920 



has removed them. A case in point was met with 

 in other members of the same group. When 

 Mendelteff enunciated his generalisation the ac- 

 cepted atomic weights of osmium, iridium, and 

 platinum were found to be not in accordance with 

 the previsions of the law, and Seubert showed that 

 Mendel^eff's surmise that the numbers were inac- 

 curate was correct. The proper sequence of the 

 elements has now been established, although we 

 concur with Dr. Friend that, with the exception 

 of that of platinum, which, thanks to the careful 

 experiments of Archibald, published in the Pro- 

 ceedings of the Royal Society of Edinburgh, is 

 now well determined, the values of the other 

 members, especially of osmium and iridium, fall 

 very far short of the standard demanded by 

 modern atomic weight work. 



It may be hoped that we shall not have long 

 to wait for new and more accurate determinations. 

 These elements, it is true, present special diffi- 

 culties, accentuated, no doubt, by the present 

 scarcity of material. Indeed, the term "rare 

 elements," originally applied to some of those of 

 Group iii., is in these strenuous and evil days 

 more appropriate to the members of the platinum 

 group. 



We presume that part ii., devoted to iron and 

 its compounds, will complete the entire work o/ 

 ten volumes, when we hope to be able to con- 

 gratulate Dr. Friend and his coadjutors on the 

 termination of their task. The complete treatise 

 will form an admirable contribution 'to the chem- 

 ical literature of this country; philosophical in 

 plan, comprehensive in treatment, and accurate 

 in detail, not the least of its merits being its excel- 

 lent bibliography. 



Our Bookshelf. 



Practical Plant Biochemistry. By Muriel Wheldale 

 Onslow. Pp. vii-fi78. (Cambridge : At the 

 University Press, 1920.) Price 155. net. 



The author indicates that her book is primarily 

 intended for students of botany, and that it should 

 be a guide to practical work. It is stated that 

 the volume is planned to supplement the know- 

 ledge of plant products which students obtain in 

 their study of organic chemistry and of plant 

 physiology. The introductiop is followed by eight 

 chapters, each giving a brief survey of some 

 portion of the chemistry of plant life — e.g. the 

 colloidal state (chap, ii.), carbon assimilation 

 (chap, iv.), glucosides and glucoside-splitting 

 enzymes (chap. ix.). The general matter of the 

 chapters is followed by, or interspersed w'ith, data 

 upon which experimental work can be carried out 

 to illustrate the points dealt with in the respective 

 chapters. A list of references to original litera- 



NO. 2658, VOL. 106] 



ture is given at the end of each chapter, and cross- 

 references are frequently employed. As to 

 errors, it is rather surprising that those in the 

 structural formula; for a- and /3-glucose on p. 4S 

 (where the formulae are used to illustrate a state- 

 ment concerning the two forms) should have been 

 overlooked. 



The chapter on plant bases (chap, x.) consists 

 rather too largely of a list of names, to which 

 are attached complex structural formulae that are 

 more likely to confuse the students who have 

 " an elementary knowledge of organic chemistry " 

 than to be of assistance to them. But for the 

 somewhat disjointed effect resulting from the 

 method of introducing the experimental instruc- 

 tions, the matter is presented in an interesting 

 form, and on the whole there is a pleasing free- 

 dom from dogmatic assertions concerning un- 

 known or uninvestigated chemical changes, which 

 so frequently detract from the value of works of 

 this type. The general survey of the problems 

 involved in the chemistry of plant life, and the 

 instructions for experimental work which this 

 volume contains, should prove both useful and 

 interesting to the class of student for whom it 

 was written, and to many others who are inter- 

 ested in the chemistry of the plant world. 



A. E. E. 



Vergleichende Anatomic des Nervensy stems. 

 Erster Teil., Die Leitungshahnen im Nerven- 

 system der Wirhellosen Tiere. Von JE. B. 

 Droogleever Fortuyn. Pp. viii-l-370. (Haar- 

 lem: De Erven F. Bohn, 1920.) 12.50 guilders. 



The author is to be congratulated on this excel- 

 lent digest of the known facts regarding the paths 

 of conduction in the nervous system of inverte- 

 brates — a work which has entailed careful reading 

 of the extensive and complicated literature of the 

 subject and skilful collation of the results. He 

 gives an account of the principal issues of the 

 researches — treated for the most part in historical 

 sequence — on the arrangement of the sensory cells 

 and ganglion cells and the course of their pro- 

 cesses, so far as this has been ascertained, in each 

 phylum of invertebrates. The internal structure 

 of the cell and the intracellular neurofibrillae are 

 not discussed. After dealing with the Porifera 

 in less than a page, there being no evidence of 

 the presence of nervous elements in sponges, the 

 author examines in turn the Crelentera, Vermes, 

 Mollusca, Echinoderma, Arthropoda, Bryozoa, 

 Tunicata, and Amphioxus, the last-named being 

 included because its nervous system presents a 

 number of features in common with that of in- 

 vertebrates. In some cases — e.g. Echinoderma, 

 Bryozoa, Tunicata — our knowledge of the paths 

 of conduction is extremely slight, but in others 

 — e.g. Annelida and Decapod Crustacea — there is 

 an extensive literature which has received full 

 consideration. The digest, illustrated by 116 

 diagrams, shows clearly what has been done, and 

 renders obvious how much still remains to be 

 done to elucidate the detailed structure of the 



