540 INTRODUCTION TO PLANT GEOGRAPHY 



recovered from a depth of more than 3-5 metres below the surface of 

 marine sediments, their numbers rapidly decrease below the first 

 few millimetres from the interface. 



Further Consideration 



There is still no single work adequately covering the topics discussed 

 in the above chapter, although further useful details are to be found in 

 the appropriate parts (almost always obvious from their headings) of such 

 books as those of V. J. Chapman and of G. M. Smith (ed.) cited at the 

 end of Chapter XV. Particularly valuable for accounts of general con- 

 ditions and phenomena in seas is H. U. Sverdrup, M. W. Johnson, & 

 R. H. Fleming's The Oceans : their Physics, Chemistry, and General 

 Biology (Prentice-Hall, New York, pp. x + 1087, 1942), while the * third ' 

 edition of Schimper's Pflanzengeographie auf physiologischer Griindlage, 

 revised by F. C. von Faber (Fischer, Jena, vol. II, 1935), gives on pages 

 1447-98 accounts and illustrations of many of the communities involved. 



The individual Algae concerned are usually treated in the volumes of 

 Fritsch cited at the end of Chapter II, and in F. Oltmanns's Morphologic 

 tind Biologie der Algen, second edition (Fischer, Jena, especially vol. Ill, 

 pp. vii -f 558, 1923), while the marine vegetation of different oceans and 

 stations is described in various works too numerous to mention but often 

 selectively cited in one or more of the above books. 



