REVIEWS 513 



south-eastern England, to whom the features of the Chaix Hills of Alaska or the 

 inland ice of Greenland still make small appeal, he is unable to believe that the 

 British Isles have suffered from a serious ice-invasion. If such an invasion has 

 occurred, the explanation given by Kendall, Lamplugh, Dvverryhouse, and others 

 of certain dry channels cut in or across spurs of Britannic hills seems simple, 

 logical, and conclusive. The melting of large bodies of ice must have pro- 

 duced, as in other countries, large effects, which present anomalous features 

 if ascribed to ordinary river-drainage. If, however, the ice-invasion was not 

 relative in importance to that which, in the same epoch, reached Central Saxony 

 from Scandinavia, some other cause must be sought for these channels in our 

 glaciated areas. This, we think, is a fair statement of Prof. Bonney's position, 

 and he has, with admirable and characteristic thoroughness, examined the field- 

 evidence over a large extent of country. The channels that are regarded by the 

 supporters of the glacial view as among the youngest features of our scenery are 

 held by Prof. Bonney to be truncated remnants of older drainage-systems, like 

 the dry gaps of a folded country, beheaded by the recession of subsequent streams 

 along the strike. It seems difficult to maintain this view in face of the freshness 

 of many of the rock-walls down to the valley-floor — those of the Scalp near 

 Dublin, for instance, which is cut in granite, and not, as here stated, in limestone. 

 The great scarps cited by the author as antique features — those, for instance, of 

 the Wetterhorn and the Dolomites — are surely very modern as regards their 

 present faces, and are not buried in their own taluses because of the transporting 

 power of the ice which surrounded them down to the human epoch. The latest 

 description of the Dublin features is due, by the by, to J. R. Kilroe, following 

 Lamplugh, and not, as Prof. Bonney suggests, to the present. reviewer, who is, 

 however, among the willing converts. 



Grenville A. J. Cole. 



ZOOLOGY 



The Mutation Factor in Evolution, with Particular Reference to (Enothera. 



By R. RUGGLES Gates, Ph.D., F.L.S. [Pp. xvi + 353, with 114 illustra- 

 tions.] (London : Macmillan & Co., 191 5. Price 10s. net.) 



The title of this book leads one to form a wrong idea of its contents, for it is really 

 a detailed account of the mutations of CEnothera, with very brief references to 

 mutations in general, and a short discussion of the part played by them in the 

 evolution of new species. 



De Vries, by his numerous studies and in particular by his work Die 

 Mutationstheorie, has made CEnothera a classical plant to the biologist. At first 

 received with scepticism, the repetition of his experiments by other investigators 

 led to a more general acceptance of his results, and it seemed as if there was now 

 an opportunity of investigating species in the making. 



Dr. Gates was among the first to recognise the importance of an investigation 

 of the cytological phenomena accompanying this mutation. Since his first paper 

 on this subject in 1907 much further work has been done by himself and other 

 workers, and the time is ripe for the appearance of such a volume as the present, 

 in which the various results are collated and reviewed. The book therefore is 

 useful, but in our opinion there is still room for a work dealing with mutations 

 in general. 



A well illustrated and succinct account of the various species of CEnothera, their 

 distribution and early cultural history, forms a useful introduction to the remaining 

 chapters. The various mutants of CE. Lamarckiana are fully dealt with, and one 



