136 TRANSACTIONS OF THE [Sesb. lxxvii. 



LITERATURE. 



(1) Smith, R. — "Botanical Survey of Scotland: 1, Edinburgh 



District." Scot. Geog. Mag., 1900. 



(2) Smith, W. G. — " Botanical Survey of Scotland : 3 and 4, Forfar 



and Fife." Scot. Geog. Mag., 1905. 



(3) Clements, F. E.— " Research Methods in Ecology," 1905. 



(4) Crampton, C. B. — " Stable and Migratory Plant Formations." 



Scot. Bot. Review, 1912. 



(5) Types of British Vegetation. — Edited by A. G. Tansley, 



Cambridge, 1911. 



(6) Warming, E.— " Oecology of Plants," Eng. trans., Oxford, 1909. 



A Revision of the Genus Cochlearia in Britain. 

 I. Cochlearia danica, Linn By M'Taggart Cowan. 



For a considerable time I have been engaged in the 

 study of the genus Cochlearia in Britain, and in the cultiva- 

 tion under similar conditions of the numerous forms assumed 

 by the very variable species of this genus. A large amount 

 of both living and dried specimens have passed through 

 my hands, and numerous notes have been made in the 

 field. Field work is of especial importance in dealing with 

 these very critical plants, as otherwise a very erroneous 

 opinion of the value of the various forms is likely to be 

 arrived at. Where possible, the plants in their native 

 localities were visited at different periods of the year. 



The cultivation tests also gave most valuable results, 

 many of the most striking forms in the field reverting at 

 once to type when under cultivation. This was particularly 

 so in the C. vulgaris group. Others, on the other hand, 

 were found to be remarkably constant. 



The present paper is confined to the consideration of 

 C. danica, Linn., as the other species still require further 

 consideration, and it is intended to treat of these in a later 

 paper. 



My thanks are due to many botanists for their help in 

 sending material for study, and to Professor Balfour for 

 permitting the cultivation experiments to be carried on 

 under suitable conditions in the Royal Botanic Garden ; 

 to Mr. W. W. Smith for much assistance in making out the 



