452 SCIENCE PROGRESS 



The question as to whether plants are able to assimilate free 

 atmospheric nitrogen has been again revived in a paper by 

 Mameli and Pollacci (Atti R. Accad. Lincei, 191 5, [v], 24, i. 966), 

 who assert that their original contention (loc. cit. 1910, [v], 19, i. 

 501, and 191 1, [v], 20, i. 680) concerning the ability of certain 

 seeds to assimilate atmospheric nitrogen is correct. They 

 further criticise and explain the contrary indications obtained 

 by other authors such as Oes (Zeitsch. Bot. 191 3, 5, 145) and 

 Molliard (Comptes rend. 191 5, 160, 310). 



GEOLOGY. By G. W. Tyrrell, A.R.C.Sc, F.G.S., University, Glasgow. 



General and Stratigraphical Geology. — The origin of coral-reefs 

 has been investigated anew in the field by Prof. W. M. Davis, 

 who has applied to the problem those methods of modern 

 physiography which have been largely perfected by himself. 

 As a result of this study {Amer. Jour. Set. 191 5, 40, 223) he 

 gives the support of his great authority to Charles Darwin's 

 original theory of subsidence. Prof. Davis points to the 

 frequent embayment of the central islands and the unconform- 

 able contact of the reef-masses with their volcanic foundations 

 as essential consequences of subsidence. 



In consequence of field and petrographical study of the 

 Carrara schists and marbles, Prof. T. G. Bonney and the Rev. 

 W. H. Winwood (Geol. Mag. 191 5 (6), 2, 289) abandon the 

 hypothesis of a Mesozoic, or even later Palaeozoic age, for these 

 rocks, and believe that they are most probably Archaean. 



In an important paper on the correlation of the Dinantian 

 of Belgium and the Avonian of south-west England (Quart. 

 Jour. Geol. Soc. 191 5, 71, 1) Dr. A. Vaughan has set out the 

 diagnostic and dominant faunas of the Belgian sequence, and 

 has demonstrated a period of local emergence in Belgium 

 during the time Si, which corresponds with a period of renewed 

 subsidence in Britain. Two " knoll " horizons are also shown 

 to exist, just as in the Clitheroe-Craven area of Lancashire. 



Mr. T. C. Nicholas has studied the geology of the little- 

 known St. Tudwal's peninsula (Carnarvonshire) in great detail 

 (ibid. 83). He demonstrates beyond reasonable doubt the Pre- 

 Cambrian age of the strip of highly-altered schists, jaspers, 

 and other rocks from Nevin to Bardsey Island, by the discovery 

 of a great series of lithologically different and quite unaltered 



