2 20 



NATURE 



[October 13, 192 1 



proved itself invaluable in predicting new facts, so 

 that it has now established itself in an almost im- 

 pregnable position. Dr. Langmuir's atom, 

 although presenting a tetrahedral aspect, is less 

 able to adapt itself to organic compounds. A single 

 bond, in the ordinary notation, is represented by 

 an edge common to two cubes, a double bond by 

 a face in common, so that an entirely different 

 structure has to be adopted for a triple linking, 

 and acetylene becomes one of the puzzles of the 

 theory. It was also remarked that the model of 

 sodium carbonate was essentially similar to that 

 proposed by Werner, suggesting that the co- 

 ordination theory might be elaborated to explain 



many chemical facts in place of a new hypothesis. 

 It is probable that the study of valency will re- 

 ceive much attention in the near future, and that 

 chemists will test each hypothesis thoroughly 

 in its application to structural chemistry, which 

 rests on an enormous mass of definitely established 

 facts, with which a theory must be able to deal. 

 In the meantime, the scheme of Dr. Langmuir, 

 so clearly presented on this occasion, forms an 

 excellent basis for discussion, and the Edinburgh 

 meeting has served a most useful purpose in 

 focussing attention on the difficulties, as well as 

 on the advantages, of the proposed solution of 

 the problem. 



The Study of Bird-migration 



HP HOUGH many valuable contributions have 

 -■- been made in recent years to our knowledge 

 of the various phenomena associated with bird- 

 migration, yet much remains to be accomplished. 



One of the most important desiderata is to 

 obtain definite information of a detailed nature as 

 to the provenance of the migrants which arrive in 

 spring, let us say, in the British Isles, and are 

 widely or more orlesslocally distributed during the 

 summer, and equally, or more widely, dispersed 

 in their winter retreats. The same remarks apply 

 to the numerous winter visitors : In what par- 

 ticular areas have they passed the summer? Do, 

 for instance, redwings from Iceland winter with 

 us as well as redwings from their wide-ranging 

 summer haunts in Europe? Whence come the 

 hosts of birds-of-passage which traverse our isles 

 in spring en route for summer haunts in more 

 northern lands, and return in the autumn on their 

 way to their accustomed winter quarters? Each 

 species comprised in these three groups of 

 migrants is in all likelihood widely dispersed at 

 both seasons, but as yet our knowledge is 

 infinitesimal as to where the summer visitors to 

 our country pass the winter, or where our winter 

 visitors pass the summer, and we know nothing 

 regarding either the summer or the winter haunts 

 of the passage migrants. 



In addition, more definite information is desir- 

 able as to (i) the routes followed by birds to 

 reach their seasonal haunts ; {2) whether the 

 young seek the same summer and winter quarters 

 as their parents; and (3) the winter retreats of the 

 migratory section of certain British bitds — the so- 

 called partial migrants. 



The difficulty in solving these important prob- 

 lems may fairly be described as insurmountable 

 in the main ; but it has been proved feasible to 

 obtain glimpses of enlightenment, and it is most 

 desirable to add to these glimpses, which, when 

 correlated, become important. This may be ac- 

 complished in detail by the process called "ring- 

 ing," and in its broader aspects through a know- 

 ledge of the distribution of racial forms, if such 

 forms are based on well-marked characters. The 

 ringing method is, however, the more promising, 

 since the data so obtained are of a definite nature; 

 NO. 271 1, VOL. 108] 



by the Marking Method. 



and all who have the opportunity should cordially 

 co-operate in forwarding the researches on these 

 lines which are now bemg carried out. 



With this end in view the University of Aber- 

 deen instituted, in 1910, an inquiry for "The 

 Study of Bird-migration by the Marking Method." 

 This work was carried on for several years as a 

 piece of research under the general direction of 

 Prof. J. Arthur Thomson, to whose son. Dr. 

 Landsborough Thomson, on whom the carrying 

 out of the investigation devolved, we are indebted 

 for the " Results," which were recently published 

 in The Ibis. The total number of species ringed 

 was about 100, and the number of individual birds 

 27,802. The total number of "reappearance 

 records" (recoveries) was 879, or 3-2 per cent. 

 But, as in other inquiries of a similar nature, 

 many of the recoveries, as was to be expected, 

 were made in the vicinity of the scene of marking, 

 and after an insignificant period of time. Infor- 

 mation of an important nature was obtained, some 

 of which forms a valuable contribution to our 

 knowledge of the seasonal distribution abroad 

 and at home of the following species— namely, 

 the lapwing, woodcock, starling, song thrush, 

 swallow, hedge-accentor, mallard, herring gull, 

 and blackheaded gull. The data regarding these 

 have been carefully analysed and studied in all 

 their bearings, and the deductions derived there- 

 from are given in detail. Regarding the rest of 

 the species discussed, thirty-five in number, the 

 data are not considered sufficient for such elaborate 

 treatment, and for these brief summaries are given 

 which afford in some cases records of considerable 

 interest. There are also useful sections in which 

 are discussed the purposes of bird-marking, its 

 history, the interpretation of results, conclusions 

 regarding bird-migration, and the value of the 

 method of ringing, all of which are well worthy 

 of perusal. 



The University of Aberdeen is to be congratu- 

 lated on its enlightened action in fostering this 

 special piece of research, which, thanks to the 

 labours and skilful treatment of one of its alumni, 

 backed by the assistance of a number of enthu- 

 siasts, also alumni, has, greatly to his credit, been 

 brought to a successful issue. W. E. C. 



