212 SCIENCE PROGRESS 



In two recent papers (" Nya Data till Kannedomen om Seve- 

 och Kolibergarternas Kemiska Karaktar," Geol. For en. Stockholm 

 Fork., 41, 1 91 9, 369-82, and " Fjallens Kristallina Skiffrar och 

 deras Tolkning," ibid., 43, 192 1, 177-87) P. D. Quesnel maintains 

 somewhat similar views to Frodin's and Holtedahl's in regard 

 to analogous rocks and structures of districts in Northern 

 Sweden. 



Coincident with the extensive reinterpretation of the 

 Scandinavian highland problem by the group of investigators 

 referred to above, in which the importance of thrust action is 

 somewhat minimised, Mr. E. B. Bailey propounds an interpreta- 

 tion of the south-western part of the Grampian Highands in 

 which thrusting and " nappes " play a predominating part 

 {Quart. Journ. Geol. Soc, 78, pt. 2, 1922, 82-131). He believes 

 that the Dalradian Schists there belong to three main structural 

 divisions, which, in descending order, are the Loch Awe nappe, 

 the Iltay nappe, and the Ballappel nappe. The second title is 

 a compound of Isla}^ and Loch Tay ; the third of Ballachulish, 

 Appin, and Eilde. Each of these divisions has its own particular 

 stratigraphical facies, but certain correlations from one to 

 another are suggested. The emplacement of these nappes is 

 considered, from various lines of evidence, to have been due to 

 movement from north-west to south-west. Great recumbent 

 folds are a feature of Mr. Bailey's structural interpretations, 

 and the elucidation of these has been greatly helped by the 

 presence of secondary folding, which has bent over the primary 

 folds into such features as the Cowal Anticline, Loch Awe 

 Syncline, Islay Anticline, etc. The work is difficult to sum- 

 marise, and even to understand by those unfamiliar with at 

 least some of the field evidence ; but it is noteworthy that a 

 group of Mr. Bailey's colleagues, along with Prof. Collet of 

 Geneva, have published a note expressing agreement with 

 a large number of Mr. Bailey's fundamental ideas {Geol. Mag., 

 59, 1922, 301-3). 



BOTANY. By E. J. Salisbury, D.Sc, F.L.S., University College, London. 



Variation. — To the Journal of Genetics (vol. xii, pp. 47-89) Prof. 

 Vavilov contributes an important paper under the title of the 

 " Law of Homologous Series in Variation." The author begins 

 by emphasising the immense variety of Jordanean species 

 comprised in the Linnean aggregates, amounting to about 

 3,000 for Triticum vulgare, between 600 and 700 for Barley, 

 and apparently, from the limited cases investigated {e.g. Tri- 

 folium pratense), these segregrates are no less numerous in wild 

 species. vSuch polymorphism, which is independent of the 

 innumerable genotypes, calls for systematisation, which the 



