PREFACE. Vll 



Barker (1869), Bennett (188(3-7), Bisset (1884), 

 Cooke and Wills (1880-1), Marquand (1882-4), and 

 Turner (1885-0) also contributed short papers on 

 British Desmids, which added considerably to the 

 knowledge of the distribution of the Desmidiaceae in 



O 



the British Islands. 



In 1887 M. C. Cooke issued his 'British Desmids.' 

 A good work was much needed at that time, but the 

 book which then appeared was most unsatisfactory to 

 scientific botanists, whatever it may have been to 

 microscopists. In the first place, it was evident that 

 very little Desmid-material had been examined, and, 

 secondly, that scarcely any attempt had been made to 

 collect together what was already known concerning 

 the distribution of Desmids in the British Isles. Added 

 to this, the illustrations were mostly very diagrammatic 

 and many extraordinarily inaccurate. Often when a 

 cell had been figured showing the cell-contents, the 

 outline of the same figure was made to do duty for an 

 empty cell, the latter being shown without its charac- 

 teristic and indispensable markings. Xot many (prob- 

 ably not more than a dozen in all) of the figures were 

 original, and one of the remarks in the text called 

 forth an article in the ' Journal of Botany : 1887, xxv, 

 pp. 355-358, by Dr. 0. Nordstedt of Lund, Sweden, 

 Avho indicated the various works from which the figures 

 had been roughly copied. Notwithstanding all these 

 defects there is no doubt that the book was of value in 

 stimulating students to further work on these plants. 

 The number of species Cooke described was 271 with 

 40 varieties ; there were also 19 species and 2 varieties 

 in a supplement, making a total of 290 species and 48 

 varieties. 



Since the publication of Cooke's book many papers 



